, _'2_SA Conference Publication 10006

DOT/FAA/PS-88/7

Airborne

Wind Shear

Detection and

Warning Systems

First Combined Manufacturers'

and Technologists' Conference

Compiled by

Amos A. Spady, Jr.

and Roland L. Bowles

NASA Langley Research Center

Hampton, Virginia

Herbert Schlickenmaier

Federal Aviation Administration

Washington, D.C.

Proceedings of a conference sponsored by the

National Aeronautics and Space Administration

and the Federal Aviation Administration

and held in Hampton, Virginia

October 22-23, 1987

January 1988

r_l:_ r_ ujc_

co_ co L)_

_Z:)| CO _ "q

O

u3

u_j

HUi

ul p_ u_

tJ

f..1 .0 i_.1

_,4=g

;lit 1_

O ¢/1 ur_

g_ r_ _ u3

o_,=l

t _

t t-._ m a_

,._ t.i _..t u.1

U,__ of Tiar_

_ ._Imlnlstmtlon

IUASA

National Aeronautics and

Space Administration
FOREWORD

The "First Combined Manufacturers' and Technology Airborne

Wind Shear Meeting" was hosted jointly by NASA Langley (LaRC) and

the Federal Aviation Administration (FAA) in Hampton, Virginia on

October 22-23, 1987. The meeting was co-chaired by Dr. Roland

Bowles of LaRC and Herbert Schlickenmaier of the FAA. Amos Spady

of LaRC and the Science and Technology Corporation's Meeting

Division coordinated the meeting.

The purpose of the meeting was to transfer significant

ongoing results gained during the first year of the joint

NASA/FAA Airborne Wind Shear Program to the technical industry

and to pose problems of current concern to the combined group.

It also provided a forum for manufacturers to review forward-look

technology concepts and for technolgists to gain an understanding

of the problems encountered by the manufacturers' during the

development of airborne equipment and the FAA certification

requirements.

The present document has been-compiled to record the essence

of the technology updates and discussions which followed each.

Updates are represented here through the unedited duplication of

the vugraphs, which were generously provided by the respective

speakers. When time was available questions were taken from the

floor; if time was not available questions were requested in

writing. Questions and answers from the floor are included with

each presentation. The written questions were presented and

an _.ered in the final session and are included in the document.

Several of the speakers did not have vugraphs; their talks were

transcribed from the recordings of the sessions, edited by the

speaker and are included. Additionally, the opening overview by

Dr. Roland Bowles was transcribed and included to provide the

reader with an understanding of the multiple elements included in

the Joint Airborne Wind Shear program.

=RECEDING PAGE BLANK NOT FILM.-."D

t

iii

I
TABLE OF CONTENTS

FOREWORD .......................... iii

TABLE OF CONTENTS ..................... v

i. OVERVIEW ................... 1

Roland Bowles (NASA/LaRC)

A. Joint NASA/FAA Airborne Wind Shear Detection and

Avoidance Program ................. 5

B. Heavy Rain Research ................. 17

i) Questions and Answers ............... 27

2. TECHNICAL PRESENTATIONS - Thursday, October 22, 1987

A. NASA Wind Shear Model - Summary of Model Analyses . . 2952

Dr. Fred Proctor (MESO, Inc.)

B. Response of wind shear warning systems to turbulence

with implication of nuisance alerts ......... 675z

Roland Bowles (NASA/LaRC)

i) Questions and Answers ....... 88_

C. Investigation of the Influence of Wind Shear on the "

Aerodynamic Characteristics of Aircraft Using a

Vortex-Lattice Method ................ 91_3

Dan D. vicroy (NASA/LaRC)

I) Questions and Answers ........ 136 _'T

D. _indshear Warning: Aerospatiale Ap;roach[ ...... 1375_

J. L. Bonafe (Aerospatiale)

i) Questions and Answers ......... 163 _;I/-

E. Windshear Detection Effect'of Static Air Temperature

Bias ......................... 1655_

Howard Glover (Sundstrand)

I) Questions and Answers ...._ _ . _ 175_ _'_

F. Airborne Doppler Radar Technology for &i d

Detection ................ 1775

E. Bracalente iNASA/LaRCi

G. Radar Backscatter from Airports and Surrounding

Areas ..................... 183_ Robert G. Onstott iERIM)

H. Radar Returns from Ground Clutter in Vicinity of

Airports... s e n 6 i e s t ; ....... 1931_ H. R. Reamer (North Eat r n v r i y

I. Wind Charles ShearL. Radar Britt Simulation (Research T;ian. _ le Inst _tute) .... 2075_

(i) Question and Answers Session Held for Items

F thru I. . 2280

J. Lidar Windshear Detection and Avoidance:'Performance

and Technical Assessment ............... 2335/0

Russell Targ (Lockheed Missiles & Space Company)

_RECEDING PAGE BLANK NOT FILW,-D }_I';_--,[-- v ........ ._"_L_i_0_ALLY BI_Nt_
ORIGINAL PAGE IS

OF POOR QUALITY

K. Airborne Doppler Lidar Detection of Wind Shear

Results of Performance Analysis . . _ [ _ ...... 253_;_

R. Milton Huffaker (Coherent Technol g e )

L. Infrared Low-Level Wind Shear Work .......... 283_

Pat Adamson (Turbulence Prediction Systems) _

i) Questions and Answers .......... 321 r_

M. Forward Looking Wind Shear'Detection Status Report

lo/n/87 ................ 323

B. Gallagher (Deico Systems) 5t/

N. Simulator Investigation of Wind Shear Recovery

DavidTechniques..A. Hinton" iNASA/Larci ............. 33591_

i) Questions and Answers .......... 361_

O. Crew Interface With Windshear Systems . ...... 365z

Dave Carbaugh (Boeing Commtercial Airplane Co.{

i) A Survey to Help Determine the Priority of

Research on Crew Information Issues Involving

Advanced Windshear Detection Equipment ...... 398_ _:_

3. OPENING REMARKS- Friday, October 23, 1987 ..... 405

Herb Schlickenmaier (FAA/Headquarters)

A. Windshear Training Kit ................ 406

4. TECHNICAL PRESENTATIONS - Friday, October 23, 1987

A. Status of FAA Terminal Doppler Weather Radar

Programs .......... 41_O

Mark Merritt (MIT Lincoln Laboratoryi

i, Questions and Answers ............ _ 478 0

B. The Advanced Low-Level Windshear'Alert'System

Operational Demonstration Results .......... 481jI _

James Moore (NCAR)

i) Questions and Answers ........... 504

C. Information Transfer in the National Airspace

System ................--- - - - - - - 507_

Alfred T. Lee (FAA/Headquarters)

D. Are Windshear Training and Recommendations

Appropriate for Other Than Large Jet Transports?. . • 517{/_

R. S. Bray (NASA/Ames)

E. Airworthiness Considerations ............. 525_

Ray Stoer (FAA)

I) Questions and Answers ........... 529577 :_,'/

F. Status Report Airborne Low-Altitude Windshear S)

Equipment and Training Requirements ......... 533 f/_

Myron Clark (FAA/Headquarters) _

i) Questions and Answers

G. Experience with the National Lightning Database . . . 539

Rosemarie McDowall (CRMi)

i) Questions and Answers ............... 542

H. SAM SAINT COMMENTS WITH RAY STOER REBUTTAL ...... 543

5. QUESTIONS AND ANSWERS SESSION .............. 547

vl
ORIGINAL PAGEIS

OF POOR QUALITY

ROLAND BOWLES - OVERVIEW

It has been real formal so far. Let's get it informal right

now. Many of you have heard, basically, what I would have

presented in a detailed overview. But because of the depth and

demands of the technical program, I am going to try and relate

what NASA is doing to what you are going to hear throughout the

rest of the day. That may be a difficult transition for me, but

I am going to try.

The motivating factors behind what NASA is doing, I think is

important from the perspective of how we fit a broader activity

within government and industry. This is no longer a wind shear

program plan draft [pointing to viewgraph]. I understand that it

is now an officially sanctioned document with all the appropriate

signatures, and it is underway. It has a number of activities,

many of you, or your companies, represent work and/or related

activities, that are in effect, supporting this effort. NASA's

role is strictly looking at the airborne systems technology side

of the question. The bottom line is that NASA is looking at

cockpit automation, crew decision aids, the appropriate

information systems and sensor technologies to deal with reducing

risk of low altitude wind shear encounter. Now (from a

headquarters point of view) this program, as indicated

previously, cuts across many of our base activities, it is

tracked in headquarters under the aviation safety program with

management provided by Code RC. Though NASA's principle role and

mission is new vehicle technology, we have always had a keen and

historically very productive history in aviation safety related

activities.

The objective of the NASA program is very clear. To develop

and demonstrate technology for low altitude wind shear risk

reduction through airborne detection, warning, avoidance and

survivability. Again, we are talking about cockpit automated

pilot decision aids. That objective implies an operational

requirement that basically puts systems on flight decks that will

promote crew awareness of the presence of wind shear or

microburst phenomena, with enough time to avoid the af_[ected are_

or escape from the encounter.

We can only be successful in this program if we have a

strong government industry interplay in carrying out these

activities. The NASA program is broken down into three primary

technical thrusts: [pointing to viewgraph] Characterizing and

defining the hazard; appropriate sensor technology to detect from

the moving platform itself; and the flight management system

integration of those products.

Hazards: We realize a lot of activity has taken place and a

lot of knowledge has been acquired about wind shear phenomena,
particularly concerning the downburst-induced outflows. Our

emphasis is focused at better understanding what is going on in

the lowest 2000 ft. of the atmosphere--to do that in a way that

we can correlate the vector winds with the other phenomeno]ogy

that impacts the design assessment in the evaluation of the

sensor technologies that we are dealing with. That is we must

know wind correlates with reflectivity and rain, precipitation

type, magnitude, quantities and also thermal properties involved

in the atmosphere. This includes the heavy rain aerodynamics

effork--A major facility has been developed and we are about

ready to start those tests.

Sensors: Our effort in sensor technology is basically

focused on a very strong in-house microwave doppler radar

program, starting with a base line of X-band systems_ We have

put in place an out-of-house LIDAR program, it involves an

industry consortium lead by Lockheed Missiles and Space,

involving Spectra Technologists, and Coherent Technologies. We

are examining the range of opportunity from ].0.6 micron (gas

lasers) to Homium (Ho:YAG) lasers at 2 microns. Today you are

going to see two presentations after lunch that show where we

stand after year one in our radar work and where we stand in

looking at the technical horizons for I.IDAR and performance

assessments in the enviro_meqts ]n which the sensor technologies must work.

Flight Management: Finally, if we can understand the hazard

and if we can sense it from the moving platform_ probably the

crucial issues become: What information does the crew need? How

will it be displayed? How will it be used (or bow should it be

used)? What impact does it have on operating procedure? So in

that _nse later today you will hear some early ideas emerging

from a sponsored effort with Boeing to address flight deck issues

associated with integration of predictive forward looking

information. T.hen, Dave TIinton will discuss some recent studies

looking at the comparison oF wind shear recovery and escape

techniques with conventional flight director command systems°

Funding: The program resources are split in this way. Net

R&D are roughly equally split between FAA and the NASA R & T

base. There is also a large NASA institutional resource

requirement to conduct the kinds of research studies that we are

talking about.

So, if we were to say: where do we stand at this point? We

think the NASA role in the overall national wind shear effort has

been defined. NASA headquarters and the FAA have signed a 5 year

memorandum of agreement for a cooperative program. The program

elements, facilities and direction are finalized and we are

completing on year one of activity. The budget picture looks

pretty promising for us in '88. I shouldn't say that, because

Congress really hasn't decided yet. But, if the plan holds as we

OR/GINAL PAGE I8

OF POOR QUALITy
understand it, it looks pretty good. And we think this program

is enjoying strong industry support based on the products that we

have developed in year one.

What I would like to do at this point is to spring into the

technical discussions that exemplify a variety of research

accomplishments achieved in year one.

8
W

ORIGINAL PAGE I8

OF POOR QUALITY

or"

©O

rr"

m

<

W

OO

wZ

<wrT_

<I_a_

_C.DZ

Zm

if)

0 _

m_

_j_o

o<

_Z

a

_ECED_G PAGE __LANK NOT FILM:-'D

5

ilL, _i_t_i/41_lL_ _L_._
ORIGINAL PAGE I$

OF POOR QUALITY

¢'x

O"

!

1...

i

p
I! I
I

OW

ulW

,,,90

Z

iii W

rr

2D0

u.l

rr

._.i

I,LI Z

n- O

OC m

,el:

!--

7-

CD

O0<I

Ii0

m

_J

Ii

Z

z0

< Vr,.0 0 Z '_ z

Z<<

w

_W

WDX

ZW

_o

Dw

wZ

OO

o_o

W

00

W

00

oOZ

r_

iii 0Z00

>-

r_

koOZi

Iii 0Z

n- O

Ii

n"

ILl

17

0O

ILl

I--

Or)

>-

or) Z<

I..IJ

00

rn

>- O

._,1 OZ

7- 0

ILl

I-- 0

00000

>-

I-ra/mmm

_..I 0
©©

LU

n-O

k-Im

._J

U_

O0W

h-00

r-r" n

i-

-lH-

>-

k--

._J

Q_ 0

LLI Z

r'r" 0

r'n

r_

n- O

rr"

UJ

-r

O0 aZ

LL0

ILl 0Z

LU

COW

nO.

LU

-F

k14_ 0

O0

CO

U2 Z

LU

n0

U.J m

"r0Z

LU

-rZ

LU0Z

LU

"I-

[3_

koO

nnn0

OC0

0

nn

U_

UJ

a. 0

00

LLI

r'r" 0

I.IJ a

LU

!-0

ILl

1.1_

I.L.

LLI

"lh- a>

nUJ Z00Z

LU

LU

-r

p-

>- <

a_

nn

LU

h- Zi

>-

noO

cl Zi

F- Z

LUZ

CCW0Z0

OC

hCO

g
U

U

luJ

I-Z

,ram

(3

LU0

I-

.J

u_

I

%.

.'eo

_m m_Q !

.o

10 ! I |\
l.e

Z

,q[

u.,0N

ZU

I-..

\

LLI l

._0

all0 -"I-,

1,1,11 ¢,_

¢,J ¢JZ

I u,I_

-- k0

11

Ixl

I-
O=

I--

nr

I

1.1_

Z

0

a

u.J

_0

<

tnO

:D

>-

i:1=

iz

(5

Z

0

I--

0

O9

I--

Z

UJ

"IO0

_.I

0

0

(D

<
I,I.

13
{D

W

O

rr

O

W

re"

O

O

rr

a.

¢r"

ill

ORIGINAL PAGE IS

OF POOR QUALITY

14
.°°

.°

t:'

t__-: ,_'_':,_ _i :_'_'_

_ :;:i_:-:-:%_--::k

"_: .:':" • ._'_ ':__:..,-',.,4 '

i

ORIGINAL PAGE I_

OF

\

15
UJ

...J

O

IZl

LU

03

LU

m

LU

=RECEDING PAGE BLANK NOT FILW:"D

,_......]_ ......ii_,_ ,,_, ,

17
O0

ILl

IL

IL

uJm

<C

uJ

UJl

C/)l m !

..II

Zl

"1"I

U.II

18

Or) lU m

_Z

n---

w_

_Z0--

12:_

_u.

-1-w

O.-J

ILl

>-OC

C_IW

..J

IU

IUOC
i.Li -:r: > o 66

__< __ fi.i

00_ rr

w Ocz_

•-_n cO I--

oonw

0< rr u_

Ig
i

.<

.<

r_

.<

Z

E

._.1

A

0

II

¢-

0

,I

c

0

i

,-.4¢,,j .c_l"

0 o0<_

0

X

oJ I

II

Z

rY

J

0

II

I I I I I

I I 1 1 I

2O

I

@

0

I

w

0

0

I

0

._ 0

O'N

_ 0

(D

_ 0

u

0
qk

Z

imam <

rr

>. ><

LU

3: az<<

ILl

3: Z

i

UJ

(3Z<0

14.

1J.I

Q. m

.-I

(3a

l.U

ILl

Q.

U'3

I-- Z<

l-Z0

(3

aw

I-Qw

rr

r[ ooI

c_Z

LU0

rn

c_

!

cq

rrW<

c_0I

I-

!

_f_o

(SONVSnOHJ.)

NIINII:I '81N'IO =10 g.LVU

oo

0')

i

"l

oo

I-0Z

,,<

o

21
._I

nI-- W

I4_

r_

111

n"Zm

r_

--I 0Z0

C)

ILl 0Z

"IC)

uJ j- 0 z

Zw

_z

n"0

OnI_. u,i

aNU.i

_0Z

m

zN

if) l--

ff)Z

W_

i--. '_

_Z

a--

O0

_z

Z_

Lun"

n'uj

uJa. " 0

U.

O'r

I-0

22

UJ

"t"

hLI.. 0

..I

LIJ >Z0

>.0Z

LIJ

r_Z

LLI

a.

ILl 00Z0

bOOZ

..1

-r. lI1

i

-l-

,-I ..1

(no

uJ_

n-o

.J

.-I

Z3

14. 0

LI.

F-Z00

,,i

uJZ

oOZ

oO

-J0

-_Z

uJ

"Ni

O_0
ORrGrNAL pAGE. rS

OF POOR QUALITE

Z

J

28
ORIGINAL PAGE IS

OF POOR QUALIT_

|

24
ORIGINAL PAGE IS

OE POOR QUALITY

|

25
• , i,, T _,T,_ T A T ,_

CF POOR qU_!J_,!TY

I!

iJ

It

26
QUESTIONS AND ANSWERS

ORIGINAL PAGE IS

OF POOR QUALI'I_

ROLAND BOWLES (NASA LaRC) - The question is, in convective

storms or in and around convective storms at altitude there is a

great deal of evidence that we are talking about highly transient

phenomenon and I might point out that one of the plans is to put

a Lyman-x mass spectrometer, using engine bleed air to go up and

make some liquid water content measurements in and around

thunderstorms. What I am saying is, there is evidence of highly

transient, time dependent, bursting of water going on, therefore

you have to define carefully what you mean by rain.

JIM EVANS (MIT Lincoln Labs) - Again, let me make two

comments. First, we are not talking about rain at 7000 and 8000

feet we are talking about rain probably below i000 feet, so I

think in planning that research program, flying around up where

you may have frozen stuff doesn't make sense. Second, for

example, in the programs that have been done in Memphis,

Huntsville, and Denver, I mean, in everyone of those cases for

example, we've flown at least in Memphis and Huntsville, through

wet microburst with a p]ane that measures drop size

distribution. So if you want insitu examples of what the drop

size distribution is in the middle of wet microburst I would

claim that you have that. And again, I simply can't understand

why you can't compute the liquid water content per cubic meter

given the drop size distribution.

ROLAND BOWLES (NASA LaRC) - Clearly you can. It is a

textbook exercise as you know. My point is, we need not know

that information to assess its impact on our data. Nowhere in

the basic physics does rain rake enter the question. Liquid

water content is the driving parameter. The point is, we just

don't need that information Jim.

JIM EVANS (MIT Lincoln Labs) - I think the issue here is

people are asking a very pragmatic element. How hard does it

have to be raining before these penalties become appropriate.

And you would like to be able, among other things, to relate

that, for example, to something they can see on their airborne

weather radar--that is radar reflectivity. I meaD, the trouble

is, nobody here, from what you have said, has any concept of how

hard it really was raining. And you said, we don't even know ho_

to talk about that, and that's what I said, I'm a little

baffled.

ROLAND BOWLES (NASA LaRC) - Look, we are talking tests. We

know what the liquid water content was. It is up to the senso_

technologists to decide what that means in terms of rain rate as

incurred for measures. Is that a fair statement?

JIM EVANS (MIT Lincoln Labs) - If you n'-ve,.1the rain d_op

size distribution right, which you are trying to do in your

simulation, then there is a rain rate presumably that cot-respond.:

27
exactly to whatever liquid water content you claim that you are

using. And that is something that I think these users would have

some sense for.

ROLAND BOWLES (NASA LaRC) - In the large scale tests you are

right. We will certainly produce that. In the wind tunnel

environment, we did not know how to do that based on the fact

that we are using similarity of flow, similarity of mode], and

similarity of rain. I defy anybody to give us the scaling for

that, that is my point. As we do the large scale test work, you

are right. We will be able to relate the rain rate to the

aerodynamic penalty.

ORIGINAL PAGE IS

OF POOR QUALITY

28
W

0

W:

ILl

W

01

0

28

N88-17617

I._

O

_d

"-W

u_
I,I,I

m

0

l'--

_L

Zz

c_O

0

30
0

O O O O O O

31
==I

W

8

o

E

32
Z

0

I

_o

P

_2

z0

-- _0

_ wz

_ X

z O_

000 0

33

>-

nZ

0

rn

_z__

uO_

z__! _

_oo. _

0
DEFINITIONS

e MICROBURSTCLASSIFIEDAS HAVINGAU _>10 M/S AND

A DISTANCEBETWEENOUTFLOWPEAKSLESSTHAN 4 KM

e DRY MICROBURSTVS, WET MICROBURST

WET IF 0,01"(0.25MM) OR MORE IS MEASURED

DURINGTHE EVENT

• A MICROBURSTMAY BE ISOLATED,OCCURWITHINLINES,

OR CLUSTERS

• THIS STUDYWILL CONCENTRATEON ISOLATEDMICROBURST,

BOTH WET AND DRY

34
7SH S_313H071_

_ oo

0

m 0

0 0 0 0 0 0 0 0

I 1 I I I I I I

__X _- __ _-.J _.L - ".

_ __.__.____-._.,_.-_,,,_.:_,. \'_

-_...._-_/. -_._-_/_.._ _.

85
OR!GINAL PAGE I8

OF POOR QUALITY

WIND VECTORS IN VERTICAL PLANE THROUGH

MICROBURST CENTER FOR 30 JUNE 82

(BASELINE) SIMULATION

RADIUS (KM)

a6 I___0 M
CROSS-SECTIONS OF STREAM FUNCTION FIELD

AT 1 MIN INTERVALS FROM BASELINE SIMULATION

5

-,x- "-" 3

w

I.-

"1"

(D

.-.. 2

Lt.I

"1"

0

J ........ 2'2:".':.' ' ' ...... I" ' ......... ' .........

I°'P oI_ _'.i,

' / ": I ",.

I I ,-. ", I ",,

! I I

,, .,j y \

l" f,

\ .... _. J

llllllltllltllllll|lllllllllllllllllll|Itllllll

Illllllll|llllllllllllllll I1|1111111111111111111

7

.--...

)

iii

5

4

IE

x 3

i-

-r

(D

.-. Z

LLI

"r

I'|lll II 111111111 Iwllll II IIIwlllll I!111111

I, ,- --.. "1.. "'-..

I I_ ",I -. "-..

I i , 1 | II l

ilil }/" !

I,,\ // I '

ol I. _/ / o

I ' • /" _s ° •

I It _% i.,,_o" .o•

_', "d °'" i"

_...----"'"

Ill I II lllll Ill lllll llllllllllll Ill Ill lllll llttl

51# ........ JL'--'.''..'.J''--'..U.'''']''i ......... I ........ '-J

i_ I I ," ........ -1.. ---. "-_

4_ I/i_"-..-"--..

• " O %% "_% i///,,';.---,.",1\ ",,

'l;llt -', _. X ",, :1

- F :_:ll//-",. !1 i _ , "4

I II I

,:,li[ i J / / ] ,

_ Iflljj i i l I l l

Zt- l!:l_l { ./ # / / /" -]

Il|

l.,V.---,_---_../" I !, _ ----N / _,w _t -_1

'[- ',',_',_ ..... "'-...... "" -I

o ....... ,]

-0 I 2 3 4 5 0 I Z 3 4 5

RADIUS (KN) RADIUS (KN)

37
CROSS-SECTIONS OF STREAM FUNCTION FIELD

AT 1 MIN INTERVALS FROM BASELINE SIMULATION

JVTIIIIIIIIIIIIIIII[IIIII rllil'llllllll|flllllll L

12

f

I

_z

I

I

o_ _ z s 4 s

RAOIU5 (KH)

ji ill ill lillllr i'l It Illll! rllllllrlllllllalllVllt

15]

/

/

I

3 l

RADIUS (KM)

38

•

ORIGINAL PAGE IS

OF POOR QUALITY
OR.TCrNA,[

......... P4,',_ ra

,OF-_ooR QUA.LITz

PEAK VALUES VS. TIME FOR BASELINE SIMULATION

400

0

-- i1_$

I I I I I I

8 @ I0 II 12 IS

TIME (MIN)

28 x 10.3 2.8_"

2.6_

2._. - 2_

2.2_

2.o_-2o_

1.2 _,- 12 _

,.o_ _

•8_- 8_,1

•_N- a

11Jo

0

-2

-6

-I0

-12

281-.. _B......

.............................

J ., / __WMIN

.- ......... A T AT _JII3A(_

_ 0 =," __ __ _IAT_ --

I I I I I I I I

TIME (MIN)

2.8 - 2

2._- o

2.0 _- -2

•8 _- -8

.4_- -lo

0 _ -12

39
_/__ xv_n

40
VERTICAL PROFILE FOR PEAK DIFFERENTIAL

OUTFLOW VELOCITY FOR

DENVER 30 JUNE 19B2 CASE

HI

@

5OO

400

300

200

I00 I

I

I

I

|

o. !

; !

! i

JAWS OBSERVED

5 AUGUST 1982

0

I

0

I

I0

AU

I I I

20

(M/S)

I

40

41
[.,/']

@

@

O

c_O 8 c_

L_J --.

(W) IH913H

111

C:)

o_z:

°C_ 8 o° °C_ 8 °

(W) IH913H

°C:) 8 _ 8

(W) IH_I 3H

(pl)1H913H

o o 8 ° 8 ':'

!

Q 0

8

w

42
LOCATION OF DELTA 191 FLIGHT PATH

AND DFW MICROBURST CENTER

600F microburst 1

400_ center 1

m_" 20 l -- DY'LTA DATA l

-200 "_ "

I i I J I I I

7153 6153 5153 1⁄2153 3153 2153 1153

distance north of runway (meters)

_°°F . ]

_oo_ -1

_oo- ., q

O_ + TRS8

! I I I I ! I

7153 6153 5159 1⁄2159 3153 2153 1153

distance north o_F runway ( metellJ

43
COMPARISON OF MODEL SIMULATED PROFILES

AND ACTUAL PROFILES DERIVED FROM DELTA 191

FLIGHT RECORDER DATA

"R

0

o

u -I0

IO_ t÷

OELTA DATA

+ TASS OATA AT II.25 MIN

-20 _ o TASS DATA AT 10.50 MIN

I I I I I

F

I I

7153 6153 5153 4153 3153 2153 1153

diatance north of runway (meter..)

20,

"-a lO

E

oE-10

-20

-3O

B

+ TASS DATA AT II.25 HIN

o TASS DATA AT IO.SO MIN

I I I I I I

7153 5153 5153 4153 31S3 2153 1153

distance north of runway {meters}

2

0

w

-2

-6 --

-8 --

-10 _

I

<_

- +

+ . / +

°

DELTA OATR _++ + _J

, TQSS OATQ AT -I'I.2SMIN'"x,,._ /I

oTASS DATA AT i0.50 MIN _++_+/__I

I I I I I"_" I

7153 6153 5153 4153 3153 2153 1153

dhtance north of runway (meters)

44

OR[G:N_L PAGE IS

OF POOR QUALIT_
Z

Z _

0

ORrcI_AL PAGE IS

OF PO(3_( QUALITy.

Ct3

CD

(NN) IHO13H

45
LIJ

I.I.I

X

l.IJ

_m

48
l.I.l

0

rr

III

>

I.I.I

IIl

>

III

m

IZl

0

0

l

,,- 8'

"0

o

A

n"

f_

m

(_ n"

W

F- z

"_ _ W

0 _c w >-

l.I. w 7- ,_

_ _ -tO 0 0

47
--I

_.-

f,i

0

r_

r_

0

r_

klO

I

i,i

r_

0

Ii

X

J,I

:I: i

v

I

_.J

r--t

C_

l 1

-1-

I

0

X

o

I

A Vl V V

Vl Vl Vl

__I _-_

0

I ! I

48
MODELSIMULATIONVS, INDEXFOR WET-MICROBURSTPOTENTIAL

SOUNDING

LOCATION

MODELED

AU

DATE (M/S) I

DEPTHOF

GROUNDBASED

ISOTHERMALLAYER

DEN 30 JUN 82 42 37

DEN 7 JUL 80 44 45

DEN 14 JUL 82 43 41

DEN 5 AUG 82 41 42

DFW 2 AUG 85 54 54

CHS 10 SEP 85 27 28

DCA 4 JUL 56 23 33

DEN 2 JUN 82 8 0

DEN 30 JUN 82 31 29

DEN 30 JUN 82 21 9

500 M*

1000 M*

*SOUNDINGARBITRARILYMODIFIED,

MODELEXPERIMENTSBASEDON 61 DBZ HAILSHAFTWITH RADIUSOF

3 KM AT 5 KM AGL,

49
SENSITIVITYTO PRECIPITATIONTYPE AT THE MODELTOP BOUNDARY

[RADIUS= 3000 M, Q(Z*)= 4,27 G KG-1 FOR ALL SIMULATIONS]

SOUNDING

LOCATION DATE

TOP BOUNDARY

PRECIPITATION AU WMIN AT

TYPE (Ms-l) (Ms-l) (oc)

OUTFLOW

DEPTH

(M)

DEN 3O JUN 82

DEN 30 JUN 82

DEN 3O JUN 82

DEN 30 JUN 82

HAIL 42 -12 -11 450

GRAUPEL 40 -15 -9 450

RAIN 34 -13 -8 400

SNOW 23 -13 -3 300

DEN 14 JUL 82

DEN 14 JUL 82

HAIL 43 -18 -13 475

SNOW 54 -31 -6 350

5O
51
Z

_Z

0

r,.)_

m E

I I

0 t._

I I

I I

0

Od

I

I

I I I I I I

0 0 0 0 0 0

If) _ _ Od

I I I I I I

1.0 0 LO 0 1.13 0

Od Od _

52
C_

I _ C_J

I I I

I I I I I

I

I

I

I

I

I

I

I

[]

I I I I I

C_ 0 C_ C_ C_

I I I I I

0 C_ C_ C3 C3

I I

C_ C_

53

::P

- CO

E - C_J

- C_J

c_J
oo

o

o

o

o_

54
0 0 0 0 0 0 0

0 0 0 0 0 0

I I I I I I I

C_ I./3 0 L_ C_

I I I

/

I I I I I 1

0 0 0 0 0 0

I, I I I

0 0 0 0

I I ]

0 0 0

..--...40

55
.'7

VERTICAL

SENSITIVITY

IO00

900

800

7OO

600

I--

ZE 500

(_.0

400

Ill

T 300

2OO

I00

0

PROFILES OF OUTFLOWVELOCITY

FOR 30 JUN 82 CASE:

TO RADIUS OF PRECIPITATION SHAFT

I

I I

I0 -5

Ii

li

41

t\

\

\

\

%,,%',

! \YO,c "., _ \,>

l ".[7 _ / / --

_,_.._s____ -.= -

I

i I t t I I

0 5 I0 15 20 25

u (M/S)

56
VERTICAL

SENSITIVITY

I

-20

PROFILE£ OF VERTICAL VELOCITY

FOR 30 JUN 82 CASE:

TO RADIUS OF PRECIPITATION SHAFT

/t i ' --I'°°°

_ I J I /

I II I --'

' /,' l I / 900

I I I / /

I '' ' ' -4 800 / t, I,=', _ /

H _ . /

h ,o I 1 700 _,

I I, I= ,T / ! I '_ -J 600

/ ,1 t _8 1

, '/ _ i':J 500 F_

, ,_ : , / _L

i ; -14oo2

_o.,, \& ', I /

l:_ 'll.a \- _ /

• _x _ l __I io _ _ _ 300

,,, X \_I

,,I _ _ l_ I %.

"-'.'-. \)-t ioo

"--"_--_-_",_ I

-''_ 0

I I I I

-15 -I0 -5

w (M/S)

0

57
VERTICAL

SEN51T IVITY

PROFILES OF PRESSUREDEVIATION

FOR 30 JUN 82 CASE:

TO RADIUS OF PRECIPITATION SHAFT

k-

(.D

I--I

111

T

I000

900

8OO

700

60O

5OO

4-O0

i\

\\

\\

\

\\

\\

\\

\\

0 I 2

P (MB)

I

3

58
IIIlUllllJlllUllllU|lllllllllJllllllllU|llUllUll

m

b0

(H)4) iHOI 3N

r_ 0_

| J I I Ill I I im ill I ||1 i i i illi l| I II1| _1| IJ II IKI I I

,L_

v

(H_) IHO131-I

5@
RHI Cross Section of Microburst

194°AZ at 1413:43 MDT 12 Jun 1982

4

.. :5

FUJITA &

WAKIMOTO

2

I0 12 14 16 18 km

C.;_AGINAL PAGE I$

OF POOR QUALITY

6O
COMPARISON OF AXIAL PROFILES FOR

TEMPERATURE DEVIATION FOR BOTH HAIL

AND SNOW CASES

5000 -

4000 -

_-J3000 -

FZ

(_9

H 2000 -

Ld

ZE

I000 -

OI I , I , I , I , I , II I I

-8 -6 -4

AT (°C)

-2 0 2

I

4

61
rr'lj

J

LUw

0-0. mX

iJ.i IJ-I

Ij..I ow_0 O n..

--0

I--

_Z

n-. 0

_n

_-.w

r_n"

a_

L.L.I

wn

iw

C_D

._0 0

_

Z

o0w0a

82
a)

m

o

x

E_

E

v

I

¢D

T

I

O

+

O

83
r,

0 0 0 0 0 0

64

0
i

65
0

IJL

I-- 0

rr0

iii

__1

k-

__1 Zm

k-- 0

iii

I-- Z

Ii0

C_Z0i

k--! 0

//0m

iii Zm

"T"

I'-

C_

n" 0

_w

OZ

_w

iii

CI-T! 0
N88- 17618

wo

O--

I

I

I.k

01-.0

I----

gO

iii

/

O_

a

n_

a

67
ILl

I--

_z

w

w

wz

In

ill

a

68
b

I--- wbb

n,'

<C

UJ

(/]

II

t J_

Ld _. X Ld

'_0

_Z

ILl b. Z _

-- Ld

_Ea.

'.='L- I....

l.d

Z

:3

oo

w 3:_w

ZaZ

--W

N _Z_

•1- _u. u.

"II- Ig

111w

OZ

I-- 01

b2a

..JZ

m-

OInno

J LU

a. (/)

Q"Z

X_I

e_w

l--

z0

np n,.

Ne_

_Z

Z_

69

ZOw

I--

rip O

la. ZI0Z

bJImZi

0000
rr" 0

LI. Zm

LUm

IC.1 m

r_

LU

a. QZ<Z0

i.- m

U) 0

Q.

F- Z

uJ

(n

uJ

rr

I1.

u. 0Z0

iml

or)

11

J

I-W0Z0

C_ W

I-

>.

c_

+I

II

F-

¢÷

U.

7O
IOmm

E

CFJ

O

Q.

rr LL

I

LL

_D

LU el)

V

B

C_

C.)

C/)

1in

71
0

u.I 0n

I,IJ

nu.I

LU0ZW

.J

r_

I-- i m

__J

W

nI-0

I-W

C_ Z

LU

._1 m

hI.-

72

___i}

_EE

°l M

4_
A

tl V

73
II II II II II II

74
UJ

(3Z

UJ /

:3

[DE

:30

I--

UJ 3aE0

I-0

U.I

i!

ii0z0

I-- z

(/)

\

\\

\

t\I\ I Q

..I 0

-r

uJ

n-

-r

I.- Q

n4{ N

9{

-!-

\

\

\

v- I- I- T-_0000

IJ.

0

¢_1 00

0

75
LU

(JZ

ILl

.J

OB

rr0

LU

r_

n- O

(J

<(

u.I

u.

u. 0Z0mu

LUa

r_

rr

r_z

(n

Lt.

76
IJ.I OZ

IJJ

_1m

nr"

_)

I-O

IILl a

n- O

I-- O

tl.I

it

LI. OZO_mem

I.-

.¢

mmm

LIJ aa

fX

.¢az

.¢

IGr)

Q

..I o

1-

I.IJ

1-

I-Q

n-

.¢N

IIt) 0 It) 0 In

¢_1 (_1 _" _"0

O

It)

¢qO

(51 OOO

O

77
>.-

l-- mm

_.J O

f_

='rl-- ZI

<:

I-- Zm

<t: O

l--

ILl Z0

oO

i

• | I0 1

-rIIII

"T"I

I---,I

0

78
<m

UJ

Ira

n- oa

...I 0

-r"

(/)

UJ

rr

I---

>-

U.

(nm

i-

(no

i-- a

uJ

n- !

::) o

UJ

rr

::)

..I WZZ<X0

..J<0m

I--

rr

uJ>Q

uJ

n- W

I--

...I m

U. Z

::)

\

\

(n

II

-I>

\

\

\

0 \

\

\

\

\

\

79

(.1W

U)

\

0W

o_ U)

I--

U.

-=

(D
m

JrLU

l-- m

O:

..J0

-r

GO

LU

"I"

I-.-

>-

LI=

or) m

l.-

U) 0

I.-- a

LU

I'I"

:::)

C_

LU

n"

::)

I--

\

\

\

0

O

\

\

\

\

\

\

8O

\

\

U4

(.)

a__

I.=

IJ=

\
m

I:1::

uJ

Ira

(1:: 0a

.=1 0

-r

r_

uJ

IX

-r

IlLm

I-

(/) 0i=.

Izl

uJ

rema

ILl

rr

I--

\

•\

\

\

c_

I

C_l

II ,, _1

0m CI_

I11 W

tC

\\

\ !

\\

\

J0

q'N0

81

It)

Lv)
I11 0Z0

>.a

I-. I11

IIIF-

,<Z

O0

IrO

IlZ

Lull

O_

Z--

<1:,,,

at)

IIIZ

LUll

VvN

AI

t.kV

AI

v

Q..

_J

r,i

_2

II N

AI

u..

Q.

82

n

(1)

"O

_9

fl)O.u

libE

elO

.m

(I) m

onO

0..
!11

p.

iii

(/)

D.

..,I

...I

f-.

i!1Z

>.

p. I

(/1Z

UJ a

>.

Fiiiiii

.-I

iii

o,Ii 0 c_

NI-,,,-

83

00

00 i

g'}
C_ ZOeememu

I--

nemnm XO

C_

LUZ

LU

...I

!-.

II

O

o_

C.)

m

Q.

Q..

0

Q.. O

I.. O

el)

mVO

C) O

T'-

^1

"O

,.OJp

II

O

C)

C_

,T,m

"O

a_

C_I

II

84
1.11 0Z

UJ

..I m

n-0Wm

_10

r'r

ILl 0Z0W

UJ0X

UJ

U.

|l ||••

• r|g Jw••• ro il,ii,

••• ||anD 6g••• i||iglia•••

(:_O

•oo

A"O

LI,,

0,,,

85

OOOOOO

Nd

--I O

t,l)

ILl

0:

"1-

I'-

0:

<t: N
Z

0

C,1

iii

nO

iii

LU

a

-.I

0

LLI

n"

I--

n-

,<

0

O

c;

IlINI'I z

SI:IOJ.OV--I NVlNnH

,\\\\\\\\\\\\\\\\\\' _\\\\\\\"

I

0

0

CO

0

I

0

0

0

/

/

/

/

/

/

/

/

/

,I I

0

0

Z 'Q'IOHS=II:IH1 QI:IVZVH

86

00

(.O

O

O

O

C)

C_

:::)

<C

IZ

U_

LI,I

=E

i

I--

uJ

I-.

u_

>.

(/)
(D

rr

,,¢

111

rr

>-

rr

,¢

a

ILl 0

:DaZmW0Z

LU

._.I

:::)

rn

n"

1:)

I--00

C---z

Z,¢:

<a

::)LU

oOD iii

_o-r

zoo

7-111

orr

WTDn"

uJ

_nw_Z 0

I--

_-_

Z_

_g

O-- 0 __1

u.!W

___w

I---J

:sw

wO

_Z

>-_

oOnnLU

--In

2g

n--_

-r-,_

_-'w

uJw

Z- r. 0

87

m

__! m

rn

000B

n"

UJ

7-

O_

O00

FOZ

LU

7-

F-00

_>-

>-re

uJo

I--Z

xo

U.IO

0

/_,/ Zm

rrawm0

u.!

u_

LI_

UJ

(_00

w_.

LUw 0

rr-n

o_Z

,_Z

¢060

ww

_r7

Zlll

7-I-- 0
QUESTIONS AND ANSWERS

JIM EVANS (MIT Lincoln Labs) - I guess I have a, you know,

certainly tearing through these calculations gives some useful

insight but I have a, I guess a real question as to whether this

turbulence model really makes sense. In the regime that you are

talking about really--in approach in landing, for example--where

you are focusing on the region below i000 feet in landing--you

are focusing on takeoff at a much lower altitude. Does the

turbulence model itself really hold up at such low

altitudes--where obviously the surface is going to cause major

breakdowns in the usual assumptions about isotropics. My model

is a homogeneous turbulence model and people use it because they

don't have anything better to work from, but that close to the

surface I'm really wondering whether it doesn't make sense to

just go at it, if you like, using actual experimental data. For

example, this past summer i_ Denver, they found that one element

of it is thermals. Now thermals don't fit into really what they

consider as turbulence.

ROLAND BOWLES (NASA LaRC) - We have a set of those data for

an unstable and yet convective environment. You've got a good

point. Let me point out, the_e is an awful lot known about low

altitude turbulence. From th<_ mid-sixties through the

late-seventies, the Air Force conducted an extensive in-flight

measurements program looking at low altitude turbulence with

thousands upon thousands of penetrations.

JIM EVANS (MIT Lincoln Labs) - You mean Rough Rider out in

Oklahoma?

ROLAND BOWLES (NASA LaRC) - No, LOCAT, not Rough Rider.

Rough Rider was a program done out there for other reasons.

Secondly, the industry has to certify automatic landing systems

a_d other things, using turbulence models at low altitudes.

There is a great deal known. Nor am I using isotropic

turbulence, if you look at the charts on the handouts, under i000

ft. there are nonisotropic properties, implemented in a way that

we have done before. Dick Bray may want to comment on this. We

have done this in handling qualities work for years. But I am

not departing from the "garden-variety-way" we've done handling

qualities automatic landing system certifications. What I am

doing is trying to apply that knowledge into this particular area

to get some insight on how things trade. I must point out

that--recall--there are 6% of the airplanes out there today,

flying with some kind of wind shear equi[m_ellt. The industry is

having to wrestle with these kind of trades. (And maybe somebody

from Boeing or Safe Flight or somebody else would like to follow

up.) I_ other words, we don't have time to develop a new

turbulence model. Obviously, we don't know what we desire to

know about low altitude turbulenece, but I think we know enough

to treat it probabalistically. As we approach the question of

information fusion on the flight deck_ How we are going to acce:s

88

ORIG-TNAL PAGE IS

QE P_OOR QUALITY
information from LLWAS and TDWR and smart airplanes flying around

with their own sources of information? We've got to sit back and

take a good hard look at: (A) Are we defining threat in the same

way? (B) Is the LLWAS threat and the TDWR threaL, and what the

airplane sees (whether it has a reactive system or forward look

system) is that data consistent; and (C) Are we going to have

airplane warning systems going off with LLWAS saying nothing or

TDWR saying nothing? (Or visa versa?) That does get into a bit

of what we do know about the lowest 3000 feet of the atmosphere,

and how both the airplane side of the industry and the ground

base side are working together on this problem; there is an

information fusion question--of pretty significant

magnitude--laying right around the corner.

JOHN HANSMAN (MIT) - If you look at your hazard threshold

versus rate estimator time constant plot, it seems to me that the

real limit is the human factors limit that you have thrown in

there at 4 seconds? The question is, where does that come from?

ROLAND BOWLES (NASA LaRC) - What I am saying is if you can

put people in a training device and if annunciation of warning

comes too late, or if they come in a nuisance form too often, the

system will not be accepted. There are strong lessons learned

from ground proximity warning in this area.

JOHN HANSMAN - My only comment is that (cut off)

ROLAND BOWLES (NASA LaRC) - I did this as a step response

(that I didn't show here) that if you arc exceeding a preset

threshold, you probably don't wahL to wait more than 2 to 3 time

constants before you tell the pilot that the smart system has

decided you have a potential hazard.

JOHN HANSMAN - The point that I am making is that it seems

to me that the setting of that time constant (the maximum time

constant you can live with) is really the parameter that

determines the exceedance probability you are going to get. If

you were to decide you could only live with 2 seconds from a

human factors standpoint, then you would limit yourself to i0 to

the -2.

ROLAND BOWLES (NASA LaRC) - That may very well be the

dominating factor, but there is also latitude here on the

threshold. What you are willing to do with the new twin

airplaaes with big engines, is quite different than what you

would do with an old four engine airplane. [Pointing to

viewgraph] I don't think you are bracketted, in here, on how low

you can go and on how high you want to go. Then the time

constant becomes the dominating factor in the overall design.

89

©RtrG!NAL PAGE /,_"

,_'-: ?OOR QUALI'_
0

0

0

0

0

0

N88:1761_
Abstract

Wind shear is considered by many in the aviation community to be one of the

major safety issues facing their industry. The Federal Aviation Administration

has addressed this problem through an Integrated Wind Shear Program Plan which

incorporates the expertise of industry, _.u$fiversities, and various government agencies

such as the National Aeronautics and Space Administration, the National Oceanic

and Atmospheric Administration and the Department of Defense. The plan is

aimed at reducing the hazard of low-level wind shear through improved training and

operating procedures, wind shear detection systems and flight guidance systems.

The flight simulator is a important tool used to address the airborne aspects of

the wind shear program. The fidelity of the analytical models which represent the

airplane and the atmosphere within the flight simulators is therefore of critical importance. The bulk of the simulation and analytical studies conducted to date ha_'e

concentrated on determining the effect of the changing free-stream velocity vector

on the airplane performance, and on developing higher fidelity wind shear models.

Very little work has been done to determine the effect of the spatial variation of

the wind field about the airplane on the airplane's aerodynamic characteristics. It

is important that these aerodynamic effects are characterized and presented in a

form which can be incorporated into research and training simulators. The research

presented in this paper is a preliminary effort to address, this need.

The objective of this study was to investigate and characterize the aerodynamic

effect of shear flow through a series of sensitivity studies of the wind velocity gradi-

.

eats and wing plarfform geometry parar.,eters. The wind shear effect was computed

using a modified vortex-lattice computer program and characterized through the

formulation of wind shear aerodynamic coefficients. The magnitude of the aerodynamic effect was demonstrated by computing the resultant change in the aerodynamics of a conventional wing and tail combination on a fixed flight path through

92
a simulated microburst.

The results of this study indicate that a significant amount of the control authority of the _irplane may be required to counteract the wind shear induced forces

and moments in the microburst environment. Itisimportant to note that the forces

and moments presented in this report are only due to the spatial variation of the

wind field,and axe not currently accounted for in today's research and training

simulators.

93
g4
:I

_,_ :I

__/

.'/

J

/

/

/

/

/

/

/

/

/
a)

mm

,._ "_

rU

L_

m

w

e m_

_E_m

m

m o

m

mmm

c_

llllI 

96
97
\

!

/

1

llLI.

ll

f

• 8 8

ll 0 ._

o o

_ _ I • ..,i .w.q

U W r,Q

o 11 E 11

_ 0

I_

0 "_ _" _ "_ _J

al

r. o

z

J

ee

0

4)

f

J

III

J

L_----

98

ORIGINAL PAGE IS

O__ _OOR QUALITY
0

im

im

"0C0

C_

>,,

r-=o

rn

99
0

llm

0"

IJ.l CE0

¢,.. 0

s._ 0

IL

r"

Q.

(/)

.i

r-

,-I

I.,=

Q. Ex

d}

s.._ 0

t-O

e_

-J

C

Jl

E0®

_ ._

xo

"d

0

_8

,-Io r__ I

.0• II II

I,.-

Q.

4-+

8¢

I_ ._

p_

u

"_= "_I

II ._,

_ "_. 8 8 iI

II II ."

4-I8

-I-00

¢,,I

r._

II

0

s... 0

q.=.

m_m

0

4-

4-

4-I

-I100
,, _.... _:..-, .._:_,.: ............. . _; _._..:!:,,,",.-'=.....:

I

101
Omm

O

l_

\

m

O

e¢

I

q

,-_1_

II

I

C

am

I

f,.

al

I_, II

ORIGINAL PAGE IS

OF_ _POOR QUALITY

102
ORIGINAL PAGE rS

Dbi'. POOR QUALIT_

?

103
1 jjl.

\\ !_ o

ID U • Q

_ U U U _,

_ D g _ o

:3 L_ L. L_

u g D m

F_ °''"

\, I

_73

OOmQ

_UUU

_OCCC

_mmm

umom

O00D

_lOmO

!

!

l"

\

'2- o 8

• •

_u 3

tt

r,.

U

8

m

o

o

o

:!.

Ig _co

? o

d) 3

o o o

o.

D

du3

? o

104

ORIGINAL PAGE IS

DE POOR QUALITY
105
E

Q.

0

m

ug

C3 o j

+

0 =

0 m

0 tO

m

m

U3

_1_ _ +

0

II u 6

li

0

r,

f-

.m

o

m

Q

0

0

am

m

m

tl

0

106
-i

I

!

107
8

om

0

"_

0

L108
i

_,|Oll

UUUU

ZZZZ

0 q 0 9

o

/

7_

_<i

zne33

8

i

8_

o

0

.._lu

Illl

UUUU

ZZZ_

0_00

I

8

o ? ? o ?

la

8

8_ 4

JmL

mil'l

UUUU

ZZ/_

o. _. ?

8

t

t

0

fl^m33

i 109
tD

_D

em

>

o_

om

U)

C

em

em

E

L0

0

m

H

Z

0

N

Z

110
ORIGINAL PAGE TS

Ol_. POOR QUALITY.

O

0 0 0 0 0 0 tO 0 0 0 0

L 0

• - 0 0 0 0 0 0 ©

O. _ .... • ' °

0 0 _ - 0 0 0 0 0

_- OC

(i t'_

• •

• "o

LO LO lO CO tO tO IO

0 o (0 (0 0 0 0 0 0

0 (Y _ _I" O0 O0 O0 O0

(I] nC

0

o

o)

4-

C

o

LI

0 © 0 0

0 e m o

0 0 0 --

0 In tO LO

'_ OJ

0 0 0 0

• e • e

O0 O0 O0

-- OJ 0 _ LO (0 b, O0 O) 0 --

111
.... -'_F

' I

' d/"' !

ij _ "

o

e_

d

2 "0

2

a_

d m

2 °

? -

2 °L

CJ

J ; , dO 0

I

i

I

I

II

lllIllll_lIlllIllllllll_

I

I

== C,

j

U g

U I

x _

_1

¢_1

... t t J

o o

enlO h "lue !3 ! i J ae'3

I

.TTR-fTIT_ 1 ]'T'rI I

U

..J

0

J ©

I _ m

I d

i LJ

I

o

,_Y

! i f-;2_ I

_I I

x

J

2 _ @J

]g 1 d"_ om

enlO h _,ue !3 ,.j jsoO

112 ORIGINAL PAGE IS

OF_ POOR QUALITY
ORIGINAE PAGE Ig

DF POOR QUALITY,

_t

........ li7'

LII_IIIIIIIII[IIIII[]I[Ill

l

l

_J

U

]

I

._J

t.J

J

J

2

u

._J I i o

0

|

"0

8

r'1

es

R')

|

£

13

£

ca

rn

(2)

|

£

"E3

r"

1:3

o

IIlIIP'_'_"I-_i{IIIIIIIIIIIIlll

[

-- o ,_-

{

I ¢...I

...J '

J

¢_{

FT'}'{IIl[Il{II[I [.I .--I {.,}_{

1

..J

I

I

d

*

gnlOh "tuat= t j_o 3

C3

I

CO

O

I

rn

t'_

O

I

I.-

[]

I I

I

[_[111 111 [[I [1 [ I111 [l 11

to -q* ¢-_ _t -- o

enlah ';ue!3 ! j,j_3 3

3

I

...I

t.J

_.J

d

_J

(.J

_J

fJ

d

_J

C.J

I

it!

_D

II

E

rn

II

r-3

II

• I

I

I

IllllllllJllllllllllm

|

[

'= T

,2.

I

_I

U

_S

I J

I °

t{ I

I ]

I u

.,q.

II

11

,,I

I{

]I

¢L¢)

IT,

0

II

iii

(.fll

l-n

113
e_lOA _lLm !:_ ! J _ao3

0

|

0

|

m

C_

II

0

L

0

0

Eli

111111||11|111w11|111|1111|

erHoA _.m!o! j_ao 3

x

x

J

x

?

0

p

|

I--

[]

0

!

i.-

m

C_

0

II

g

_llllllll

C_ 0 C_

_nlo A :lu_ I:_{ JJ_3

Z

?

{I

8_

O

{I

m

I

I-'I

IIl_llllllllllllllllllllll

0 c_

enln A _I,,,,, lo {J./._o3

N

I.JI 31

,.7

,_i' @.

,2 |

,2

_ 0

_Y

114

....._,iNAL PAGE IS

OF POOR QUAI,EI,_,_
i ' ,

1

o

' g

.O-E. ]50O, i_. QUeLLITZ

-fi

j En°

_T m

J o

tJ |

J_

0

m

o

enlO^ _ue!:i ; ;_1

|

I,-

m

I

m

¢'3

|

i---

r7

,q.

o

I

o o _o

an I1a^ _,,,,!: ! ;;ao3

e,,,

r.J _D

|

(-J _D

_, ,

m

,2

|

D

Q

o

l I

I

IIIllllll|llllllllllllll]lllllll;l[li ]

gnlOh "lue i_ ! J_9o 3

]

I

II

m

(_,t

(J

II

IJ' m

II

Jo

(_t

p

o

115
U)

G)

nor)

em

>

am

a_

U)

cco)

0

W

m_

E

0

E

m_

0

cw

m_

m

C

C

e_

tO

m

0

et_

0

re_

m_

0

0 --" m_

w

116

ORIGINAL PAGE I$

DE POOR QU/_LITY
w

,p

OR!G_FJk L PAGg l'_

D_ POOR QOALIT_

I_,0 •

J

9

7

..... !i

i

:...;

f_

)

117
®o o

_D _-_

0 _

_._ .,..4,__, _

O* _ Od U "

-,_s -,.a _.) ._ a) i.*

,I

m.4

o,.4 Q)

--* tO

i

/

\

\

118 ORIGINAL PAGE IS

OF POOR QUALITy,
i

t

-- -e

o

8

0

(.I

-I0

-IZ

-14

-_e CLa

, +E==I

I

I

I

i

FCLa r-L_ CLG CL_ CLa CL_ r_a CL%.

_ _ vw v_l vX w_ _j

Q W_ng R Wing and Stclb, I _zer

3.0

Z.S

,.0]

1.5

1.0

O.S

n.o

-O.S

-I .0

-! .S

I

L

Co%.Co_Co_CoG Coa Coa Co_ Co_ Coa

0 WinQ I=! Wing and Stobi I izer

4------

.,---

k]

"0,4

-0.11

-I._

-I.B

r

-t. 4

Cv. Cy a Cy%_ Cy%. Cv%,_ Cv%z Cy%. Cy,., Cv%z

O i4ir_ R ilfinl_ _ St_lbl i izer

.IB

14

Iz

9

"_ to

4

-z

-4

O. IO

0.06

0.00

-o.,,,!

-0. I0

U

-O.tS

LJ

"0._

O.m

0.16

__ o.12

>o

D.II

l.l

0.O4

0.01

"41.04

L...+ "

, , • ---

CLu. CL_a CLux CL,_ CL_ {::L_ CL n CL,._ CL.z

rl Wing R Wing end Stobi I izer

"' L.

Co_., Cou_ CD_z CO_,. Co_a CO,,z Co._ Co.a Co.,z

0 Wing R Wing ond SLobi I izer

_"1"1, _ _ ,I

Cy.. Cyul _ Cy.z C_v. Cy_ Cyvz Cy.= {:Y-u CY.'z

riving FI vi_g and St_bl lizer

119
1Zr

o

ir

4

°! _I

g

Zl --

hZ

1.0

0.1

0.8

i 0.4

O,Z

O.O

-0.2

0 wirg R Wing ond StObilizor

C_%,,c,,%_C.,%.C_=..c,,= _ C,o c,,° C_%.

0 Wing 8 w,_ _ Stob_I iz_r

O,O 1

O.5J

0.0

-0.!

-5

_ -10

o

o -ZlD,

8 "

u

.'in

--i

-4O

O.OIO

-O.CO_

C4E_, C(,._ CL,., = C.e w C,Z.,,_ C,tvz C.L.,,, Ct.,_ C_.,,_x

f'l Virlg FI b'irQ _ Stc_bl I izer

E_

C,_, Cmuw Cm_ Cm,_ Cm_ Ca_ Cm_, Ca_w Cm_

0 Winlg 8 Vir_ Grid Stcbl I izer

r_: i_l

I

i

[]

On., Cnu_ Cn,_ Cn,_ Cn,.,_Cn,,.Cn,. Cn._ C,_,,="

0 WJnO 8 wing one St.oOl lizer

120

ORIGINAL PAGE I8

OF POOR QUALITY
i

c/)

m

(/)

mD

>

im

Im

N

mm

B

oD

C

121
\

\

\

\

\

\

\

\

\

\

\

\

\

\

\

\

\

\

\

\

•

/

/•

/'

/

\

\

\

\,I I I I I

I

•I

\I

•I

\i

•I

\i

I

I

122

ORIGINAL PAGE IS

OF.. POOR QUALITY
<

......................... ,,_ttt

........................ .,,+ttt

........................ .,,Pitt

. ........................ ,,lift

0 ,4- CO (M (/_

¢0 ¢_1 (.0 ---+ LD

(M (/_ 0") 0")

¢0 ¢X.I ---+ .---+

o

"tJ '_Pnil;IY

llm

:3

m

"o

rr'

123
li I -

/

F

oes/L "sJoeqs ^

8

_eS/l "sJoE_.lsn

.4_

m

0

124

ORIGINAL PAGE Ig

OF POOR QUALITY
!

J

f_

s_ou_ "paedsJ!O enj_

,..a

o

_L_ _

_. --__

_'__

_ - {1 °

" _

' T

6ep "al_

125
__:.- {]

oo ul 8c_,_.p

t,

,i8 m

m

0

t

J

)

J

j_

_8:.

_°

- f

m

ul _ k3 ul

126

.,.IG_NAL PAGE IS

OF POOR QUALITE.
/

f--

2--

u_ul

ORTCT'_'T'\L PAGE Ig

.OF /_05JR QUALITY.

v..

\

7

f

_3ul

8 ; 8

Uou I e_uoNo

127
, i  ̧ _i-_I

8

_-.-.;.

;::

iI

• °

Q3 u! _o

. p

J

-....

8

8 2

i

8

-7

J

\

)

o o ?

0 0

l.i__

8

_ .-.-,:

"'" S

_'_. °

..... "Llr

___m -_

_--__

J

°

o o ?

x0 u+

jw

o

§ s

5

128

:,.,.;_ AL PAGE IS

..T ? 3 OR QUALITY
i t f

I i

0 0

- _i_ -

_ ._...---

I

W3u!

8

?

\

f

0 0

8

_ ,,,,m

°

= o 6 6 _ 6 6 6 o

_3 u! erauaqo

_L_ -_

_ __

2

0°oo.'_

°.=.- ::.- ....

_.-_ __ _ _ _ _I_

Uou ! a6uo_o

129
o

co

O) O) (¢3 "13 "13

oo 8

, LO

li Oo

8 .

OJ

-, o°

-_----_--_ _ _ ,..

..... I- ...... -]_

t

r'-

o

o

o i.o o LO Ot..O

oo

6_, !_Joq_,no IoJ _uo3 q3"_ !d

J o_,OAa Ia j o _,uaoJ ad

130
_" o,J

O3 O3

Q) O)

"13 "13

0 C3

0

0

1-

0

0

co

0

0

L_

0

0

Jo

0

qo

0

O4

o _ _ "_

6_, ! J oq_ no I o.J_,uoo I I od

O)

"13

oo -_

o -_

0

o

0

0

0o

I O_Oq. j.o _ueoJed

oo

0

0

181
132
J

U)

L_E

rc

(3)

comm 0

c-O0

U)

t-O

im

=#==p

_J

>,

_3

U3

133
134
oE _

o 0

_ o _

n-'

.._ '10

o _,o

_o° o= °_-o¢- o ®

_ °_ .._ _.=

EE ,_'--

o° _o_ o_-_

(:D < 00

135
QUESTIONS AND ANSWERS

RICK PAGE (FAA Technical Center) - Do you intend to do any

research work into asymmetrical microbursts and also multiple

glidepaths?

DAN VICROY (NASA LaRC) - We used a symmetrical microburst in

this case but flew off to the side of it about 1500 ft. so that

we would get asymmetrical effects. The shears are transformed

into the body axes yielding asymmetrical shear gradients as we

penetrated the microburst. So, we essentially did take into

account that effect. Certainly this is just one example. I plan

to look at more complex aerodynamic codes to compute the shear

coefficients of complete airplane configurations. Another study

that could be done is to do more of a statistical analysis of

what kind of changes you are going to see with a variety of

different kinds of microbursts. I don't plan to do that myself,

but that work certainly could be done.

136
N88-17620

b

LANGLEY 22110187

WINDSHEAR WARNING

AEROSPATIALEAPPROACH

JL BON_FE

137
n ° 464.276/87

Page I -

[. SUMMARY

Although our A300, A310, A3OO/6OO are yet automatically windshear

protected by the _floor system AEROSPATIALE has on study

windshear warning system according to AC 25 XX and AC 120 XX.

All the numerical values used here after have not the mathematical

rigour related to an exact science, they just allow us setting

targets. They are milestones, they also lead to marks welcomed in

our design process.

We set up targets, conservative as far as possible, and check using

marks the good behaviour of the system.

We keep in mind at every moment that : the more confident the crew

will be, the more flying safety will be improved.

The following paper is concerned by future onboard windshear

warning system and the AEROSPATIALE approach.

138
n ° 464.276/87

Page 2 -

2. MILESTONES : LOW ALTITUDF WINDSHEAR PROBABILITY

Several reports or study sponsored by the US Administration (NASA,

FAA), Nimrod and Jaws pro3ects, Professor T. FUJITA publications ...... etc ....... makes the windshear phenomenon more

comprehensive.

Some parts of the world seem to be more sensitive. They are

generally situated between the two 40 th parallels and more

particularly in the continental areas.

Europe seems to be free of windshears. But, in France, we observed

strong shears near by the mediterranean sea (MARSEILLE,

MONTPELLIER, PERPIGNAN ...... TOULOUSE).

All those interesting remarks cannot help us in determining an

occurrence probability for a low altitude windshear.

(Slide I) Fortunately the amount of accidents or incidents observed

over a 20 years period is low, nevertheless it allows us in

defining a maximum milestone in a sensitive region of the world.

139
n ° 464.276/87

Page 3 -

3. THE MARKS : WIND MODELS

Setting up our windshear warning systems we are supported by :

3.1. Accidents, incidents wind analysis mainly issued from BOEING

studies, also called historical gradients (slide 2).

Their probability are such defined.

3.2. The AC 12041 (slide 3) whose probability is unknown.

3.3. The windshear training aid wind models whose probability is

also unknown.

3.4. Some three-dimensional downburst models one can fit in size

and intensity. Their occurrence probability are obviously

unknown.

We will try to estimate the model's probability matching them

w,t _ historical gradients.

To do so, we use the severity factor (slide 4) called "SF".

Using "SF" we define the weight of the shears for taking off

historical gradients (slide 5) and for landing (slide 6).

Using the same observer we weight the windfields (slides 7, 8,

and 9).

We can so appreciate whatever the wind modelization is.

Now we can compare the "SF" and balance the windfields versus

the historical gradients (slide IO).

The same "SF" weighting can be used for windshear training aid

wind models (slide ii).

Those weightings lead to the general comparison (slide 12)

between historical gradients, windfields and wind models.

The comparison slides 12 and iO comes from a visual analysis

but two observers can help us in the comparison process :'°WSF"

and "PSF" (slide 13).

140
n ° 464.276/_7

Page 4 -

4. THE TARGETS - AEROSPATIALE WS WARNING SYSTEM

Considering our in flight experience, and the AC 25 XX and AC 120 XX

demands we set the following targets (slide 14).

4.1. Performance

We have to detect the shears whose probability is equal or

lower than 1.10-6. If the system does not detect such gradient

we have to show that the aircraft can take off or land safely

within the common safety rules.

4.2. Nuisances

Nuisance can have several origins nevertheless none of them

could occur with probability greater than 10-4. Taking in

account pilot training or protection of sensible areas by

ground aids (LLAWS) we relax active or latent failures

probabilities in accordance with AC 25 XX advices.

On the other hand, in the case of nuisance performance warning

we cannot tolerate a warning rate i00 times or I000 times

greater than it could really exist.

So, as we did in the past with_floor system, we are

developing _or the future a windshear warning as credible as

possible for crews, mainly in the most critical part of the

flight : the landing case.

141
n ° 464. 276/87

Page 5 -

5. WINDSHEAR WARNING SYSTEM

THE AEROSPATIALE APPROACH

(Slide 15) WS warning is balanced by comparing longitudinal shear,

vertical wind ("SF") properly filtered, actual aircraft energy with

minimal aircraft safe energy.

Warning is sensitized by each headwind increase (short period) and

desensitized according to the longitudinal mean wind (long period

input) avoiding as far as possible the effect of mean turbulence.

The computing principle of AEROSPATIALE Windshear Warning System is

as follow (slide 16) : it could be implemented in digital AFCS.

142
n ° 464.276/a7

Page 6 -

6. NORMAL PERFORMANCE NUISANCE WARNING

Considering the time of exposure and the nuisance for airlines or

air traffic control of frequent undue go around AEROSPATIALE

focused its research on landing case, without forgetting the take

off case.

In landing case AC 2057A provides us with a simple means of

atmosphere modelization allowing the knowledge of wind probability

and related turbulence.

Just a problem : the observed wind probabilities don't go further

10-3 so we have to continue the model linearly maintaining the

turbulence and mean wind relationship.

Results on (slide 17-1-2) allow to define a safe threshold in the

world of AC 2057A. The warning threshold can be set at a point

guarantizing a level of improbable nuisance warning by landing.

Similar analysis was performed for a fixed threshold (2 to 2,5 kt/s)

according to a properly filtered "SF" (slide 17-3).

AC 2057A leads in that case to a nuisance warning level of 10-3 to

10-4 by approach.

Several piloting technics can also be implemented for decreasing the

number of performance nuisance warning. Those technics such as

decelarated approach, ground speed mini are not introduced in

today's evaluation.

CONCLUSION

The theme we have here developed is mainly supported by engineers'

assumptions considering the lack of reliable statistics.

Nevertheless we have used as far as possible the windshear

phenomenon knowledge for detection with sufficient credibility.

143
_From NTSB 28 accidents/incidents due

to windshear in 1g64-1 g85 period.

*About 30C0 US AC Performs 5,000,000

Lake off or landing each year.

*Probability of severe low altitude

windshear = 10-6

144
4

0

-2O

-,_0

- = TALVI_

Q

UAL209 ORD

"_ SE+AX

o

PA 75g MSY

- ,, m,tFT

X = DISTM¢I[lqa]4BtAKIEI_EIJ£ X,q_+

! I i

0 .5000 .,10oo0

145

J
1

///// Z

.-11 /

2:

t,DZZ

<1: Z

::I= Z

ELi

"1"

¢"4

ORIGINAL PAGE IS

C? POOR QUALITY ZZ

t,_ ,-"-,,,

CD

b-" Z

,0

!

\

#

%

i

I

I

l

II

II

II

00

i

0

i,

146 i 1

iLL X

V_0

i=====-..

j.

q
t

0

dE/dr = M . [ Cte - Vxai r . Wx + g . Wz ]

0

SF = [ Wx g/Vxair * Wz ]Lim +

0

headwind < 0 downdraft < 0

SF is in Kt/s

147
mWU

m.L Zm

,,,,,,, Q

O_

¢w

,.--I

Z

I.,I,.I

¢N

"v.

'%

_q

03

Lt3

(3..

L0

ELi

.<

...I

EL=

I.t.I V

.<

r.Y

LLX

OQD

== QI

L_ZN

LL

EL

LL_

.4:

I.--

148
MQmaI

z=

m==,,=

O_

,,,,.J

.<

m

L9 _;

EL

),--

I"L_x! ! !

,-,I

t-,

.<

ELi

.<

.,.,,I

CN

Lth

.<

)=

I--

I¢}

m0

I,,,-

l,-- X

149
Z

._g

m

u_

Z

g,

N

4

D

Z

m

z a4

O

• L

t

!

Q

Q

Q

150 C,;-,[GINAL PAGE IS

OF POOR QUALITY.

m

r'

Q

LL

EL

X

Q

Q

Q

Q

!

O

Q

!
t

/

i

I

I

0

!

m

T- O

ka. X

'0

151
a:: z

c_

...2 m

C_ Z

Zm

m-- Q=Vm

u.. M

l--

u_N

0

Q !

152
!

_0

"4-

%J qJll _._

OR-TG _rN4L PAGE IS

OF kOOR QUALITy

+

÷

÷

I

I

v

_II ÷

÷

+

+

+

q-

+

", l _ /

153
a

U

g

Z

m

R

Z

m

m

l

I

l

m

IO

m

Z

Z

m

04

¢'4

tY

Z

O

r"

Z

m

_q

154

IV3

Z

,-J

t._

¢3

O

r

Z

m

ir--t

00

...L3

¢3

0

0

_q

_,,0

Z

II

uJ

Z

m

ORIGINAL PAGE IS

OF. POOR QUALITY

Q

,O

o

m

pu_

X
r

1

ORIGINAL PAGE IS

OF POOR QUALITy

WINDSHEAR TRAINING AID

rw4524 L6A xa"_

• Md_kld IVr,_

÷

+

÷

=_

w_

9_.

¥

+

+

+

+

+

m

+

+

÷

+

÷

÷

+

4-

+

+

+

155
Lc,.__ear

/.z.d _"#l'.llfl

U II.I

/u, etz 2. o9 o R D

CO _26 DEN

PA F5.9HS Y

Wind/,Coda//¢r._

W,;W PfoJe/ #"Z

w'1nd HMe/ Alr.5

Wiod _oJelNr4

__,$L .,4g4 DEW

_4 6# 3FK

EA 69S A.TL

TWA _624 L,OA

f wind _¢ld iVr 4

AC/20.4/ W/od f/eld #r 6

Wind ,ClWd,Of'dO

_£z_O00

25000

,4 2000

/gO00

2 2000

Z 2000

2. _O00

32000

70O0

_ooo

_oo0

._8ooo _zOoo

2 4000 21zOO0

26000 28000

2..F

4'.

2.._

2,8

3.5

3.7

4,.t

._5.8

,4.6

4o2

156
4

- Detect 10-6 or ¢ 10.6 cases

If" no detection show the good behaviour

or the aircraf.t

Warning due to Active Failure

AC 25 XX

Lack of"Warning due to Latent Failure

AC 25 XX

due Lo performance

10-6 (Landing case)

157
-Compare shear and vertical wind intensity

with AC energy and safe minimal energy

- Sensitize energy thresholds when short period

head wind increases

-Desensitize energy Lhresholds in consLant wind

if thresholds are sensitized

-Means angle of attack ( measured or estimated

V,Weight,CLaoa,Nz... )) ground speed,true air

speed,pitch attitude,f/s position

(

speed,vertical

,altitude

mm

158
Milll

ORIGINAL PAGE IS

D£ POOR QUALITY

d

q:'-_

?-

W k

"_- . -- ._

m

4_.

o_

(:}

159

I--

I

i

m

==

==

m

i

F,,,.

ct=

0

M.J
I i I

i_I I \

2_ i I l,Ii \

_E

Q o Q

160

OPJG1NAL PAGE IS

OF POOR QUALITy
w

,e

--J_=

, <

Z

.< <C

_J _-- r',-

_C=O

t

\

161
pORIGINAL PAGE IS

c,_" POOR

212

f._1

<

Q..

\

\

\

\

\

!

R

.'0

'O

O

Q

162
QUESTIONS AND ANSWERS

KIOUMARS NAJMABADI (Boeing) - I would like to know if the

alert criteria is based on energy rate of,change or is it based

on energy margin?

J.L. BONAFE (Aerospatiale) - Both. Just a moment. [Pointing

to viewgraph] The minimal energy is defined by the threshold you

have here. That is right. But, you increase your energy taking

your angle of attack, considering the derivative of the

horizontal shear, and the vertical shear. So you increase your

energy estimate by the shear estimate. You don't compare only

the energy threshold and the incidence estimate. It is a, sort

of, rate increase in energy. Okay?

KIOUMARS NAJMABADI (Boeing) - So what you are saying is you

are estimating your energy loss based on your energy rate of loss

and then you are comparing that with your margin, am I correct?

J. L. BONAFE (Aerospatiale) - Yes. This is the way it is

implemented.

163
m.

tim

tim

w

N88-17621

®

e_

W

C

=RECEDING PAGE BLANK NOT FiL_,ZD
0

..m_ I_ • • • a.. • •

IX::

166
0

'T'

0

167
¢/)

ibm

-j

@

0

! t

(,._)ONW_'^

168
0-

m

,.I,D

o o o _"

_. _ e,} e"l

>

/

8

0

I

169
]h,,

_e-

.,J

P,, M,J

t_tal

I_

170

ORIGINAL PAGE IS

OF POOR QUALITY,
4_

Y

Q. OO

t_

L_

>

J

11 __ I R

I"

Ioi

(o)N

171
bead- rind

(k_rr.s)

-SQ.J

25_

vertical I

vi_l 9q

(k_rr.s) I

-25-J

i_ioa_I 2_7

a Jz_-pe_ J.SQq

(]mo-r,s) I

12_-_-,.___._

bei_;_ 6_

6

pi't.ch

angle

(deg)

alpha.

bod_

(de_).

shea_

(g)

5DC2g--r

e-[

a-al

g.9_

-B.2..t

.1,_0.-[

O.Ol

| ii

zd 3_ _ 5d 6d

time (see)

$

Simulation W it h-o.ut

Temperature Bias

172 ORIGINAL PAGE IS

DE P-OOR QUALITY
e,,

beaduind

(]umcs)

vertical

ui_Kt

(kemP)

SIHIL_TE]) L-lOLL

25

_2 J

(]mocs) l_-J

bei_ 6eO_

pil:ch

a.w9le

(deg)

alpha

body

(deg)

sbeaz _

(g)

f ,

20-1

8..J

e.2.

--6.2, ,

1.9-

0.5,

O.O

d ld- z_ 3d. ,W 5_ 6d

*.he (see)

Simulation

Temperature

With

Bias

173

ORIGINAL PAGE IS

OF. POOR QUALITY
c ._c "o

em m

em

_) , _' , , LU

174
J

JIM EVANS (MIT Lincoln Lab) - In the back of the handout

that you will get tomorrow that Mark's talk, will be some of the

TDWR results. You know there have been a lot of people who have

been looking at mesonet data associated with microburst, surface

sensors where they do get delta T versus velocity. I would say

that it is far from a clear picture that you can always count on

temperature drops. There was a little hint of that in Fred's

discussion today. You know, at one point he showed a curve that

showed a big thing but on the other hand there were some othe_

situations where you wouldn't get much of a temperature change

and in fact, I would say that this mesonet data, shows some

temperature decrease, but it is certainly not enough that I would

run around arguing that you could clearly reduce your threshold

by the amount you've assumed under that circumstance. I think in

the case of the planes, I am not quite sure you get data out of a

plane when a plane crashes but that is a very small number of

events and probably doesn't reflect the total situation.

HOWARD GLOVER (Sundstrand) - What we also need however, is

data in turbulence but not severe wind shear. Boeing conducted a

survey using just that kind of approach, but they were measuring

essentially the F factor and at that time data on temperature

wasn't gathered. Data on accelerations was, also rates of change

of energy. We need something like that to leave gust turbulence

in, or to disprove the usefulness of a feature like this.

...... AL PAGE lr_

OF POOR QUALITy

175
w

\

GJ'"J'_'qAL PAGE IS

D_," POOR QUALIT_

[[[[[m ""

CD

O

.J

O

U

_- H

K U

W

Q

PRECEDING PAGE BLANK NOT FIUV,"=D

N_8:17622

/

/

177
i

i

178
1,

ONYG.[NAL PAGE IS

,OF POOR QUALITY,

:°

o izt,- <

_ = n'_- .

___

•-_ _jo.__ _ __.__

®_'-®_ _'1 " .._o

179
z_

:5 0

__=

0 c

i i

=.,o_ ,,=, ,.,o

_= r_.. _ 0:2

°" • C___

, _==: _" _ z< o _,_

< ,. > _o® _

=_'.? =:_ oo =<oo _ =o

O0 a:..

-<"' _ _- _

180
#

_z

i

<:

¢0

>-

O

m

t_ co

0 o m

cs _

O_I_oAL PAGE 1"8

_: QUALITy

--- iI"

.v-1 _/

_|l i/

•_l _i

.. :i j

°-+Mo

o

__

',,,' • co

=1"131"

m

0,<

181
N88-17623

P

Presented at

First Combined Manufacturers' and Technology

Airborne Wind Shear Review Meeting

October 22-23, 1987

RADAR BACKSCATTER FROM AIRPORTS

AND

SURROUNDING AREAS

Robert G. Onstott

Environmental Research Institute of Michigan

Advanced Concepts Division

Radar Science Laboratory

P.O. Box 8618

Ann Arbor, MI 48107

(313)994-1200

The description of the clutter environment encountered during runway

approaches is important in the development of aircraft instrumentation to

detect microbursts or severe low altitude windshear. The purpose of the

effort described here is to provide a description of ground clutter at and

near airports. Realistic clutter scenes will be assembled using highresolution synthetic aperture radar (SAR) data for incorporation into the

NASA LaRC Microburst Simulation Model.

The Envlronmental Research Institute of Michigan (ERIM) has assembled

an extensive inventory of SAR data. The archive has been examined for data

collected of airports at an X-band frequency, at angles near grazing, and

from which accurate radar scattering coefficients may be extracted (i.e.

data has been recorded digitally and includes calibration target arrays).

The Willow Run Airport located near Detroit, Michigan has been

overflown many times over the last 15 years and will serve initially as the

principle airport site. The first clutter scene has been assembled. These

data were obtained on December I1, 1984. The depression angle is about 22

degrees and the antenna transmlt-receive polarization Is Vertical-Vertical

(VV). Analysis has begun by identifying potential contributors to the

clutter background at and near the airport. The range of cross sections in

a 6 km x 12 km region about the airport is being examined. This will be

further broken down into the various scatters and into categories of like

scattering properties.

PRECEDING PAGE BLANK NOT FILIV-'I3

183

, /
r_

co

o

i

co

O2

InO

n

reET)

¢.-.

rr

184
i

o

I

nm

oi

• i

185
O0

0

O0

l

rr

lP

O_

.o 0 E

_ x CIZ ("

r- W < -_-

r" (I) _ '

m 0 < _:

_ o iF_ o

186
',"t

co

o

• ¢0

rr

t,.t)

m

0..

0

187
188

ORIGINAL PAGE IS

.OF. POOR QUALITY
i

p_

CO

C)

CO

OZ

F

0 • • • • • • • •

R..

189
i

0

i

0

m

o_

c- "0

0 • • • • • • • •

190
r"

oo

o

i

r,,..

• oo

• cc

,e

oO

_-- (xj CO

v v V

191
N85 17624

4

RADAR RETURNS

FROM GROUND

CI. UTTER IN VICINITY

OF AIRPORTS

RESEARCH GRN'Fr - NASA - LANGLEY

RESEARCH CENTER

NORTHEASTERN UNIVERSITY_ BOSTOi% MASS,

PR INC IPAL INVEST IGATOR:

CO INVESTIGATORS:

GRADUATE RESEARCH ASS ISTAI'ITS:

H,R, RAEMER

R, P,AHG#.VAN

A, T_,HATTACHARYA

Z, XU

S, BHATIA

PRECEDING PAGE BLANK NOT FIL_D

193
OBJECTIVE OF PROJECT

TO DEVELOP A DYN/VIIC SIMULATION OF THE RECEIVED SIGNALS FROM NATURAL

MAN-MADE GROUI_ FEATURES IN THE VICINITY OF AIRPORTS, THE SIMULATIOtl IS

RUN DURING LANDING AND TAKEOFF STAGES OF A FLIGHT, MODELLING OF CI.UITER

BASED ON MOST UP - TO - DATE THEORIES AND RESULTS AVAILABLE

194
NOTEWORTHY FEATURES OF SIMULATION

(I)

(2)

COHERENT SUIVIVIATIONOF COMPLEX VECTOR FIELDS OF SCATTERED

WAVE, IMPLYING THAT:

(A) RELATIVE PHASE BElWEEN SCAl-rERING CELLS IS

ACCOUNTED FOR

(B) POLARIZATION OF SCAI-IERED FIELDS IS ACCOUNTED FOR

VELOCITIES OF RADAR AI'IDSCAITERING CELLS ARE COMPUTED -

DOPPLER SHIFT IS DETERMINED FOR RETURN FROM EACH SCAI-rERING

CELL

195
NOTEWORTHY FEATURES OF SIMULATION- II

C3) MODELLING OF COMPLEX ANTENI_IAPATTERN

(A) IN TRANSMII-I'ING MODE-GENERATE B AI_

COMPONENTS OF COMPLEX RADIATED (ELECTRIC)

FIELDS FROM X AND Y COMPONENTS OF COMPLEX

APERTURE (ELECTRIC) FIELD

(B) IN RECEIVING MODE-GENERATE X AND Y

COMPONENTS OF COMPLEX APERTURE (ELECTRIC)

FROM 8 AND I_COMPONENTS OF INCOMING

COMPLEX (ELECTRIC) FIELD

FIELD

(4) MODELLING OF TIME FUNCTIONS

(A) TRAJECTORIES OF RADAR AND MOVING CLUTTER

SOURCES, UNDULATING SURFACES (E,G. WATER

SURFACES)., ANTENNA SCANNING PAl-FERN

(5) EM COMPUTATIONS PERFORMED IN FREQUENCY SPACE-CA_ BE

FT'D BACK TO TIME DOMAIN

196
NOTEWORTHY FEATURES OF SIMULATION- III

(5) MULTI PATH EFFECTS

(6)

ll_O AI_E)THREE-BOUNCE PROCESSES CONTRIBUTING

TO RECEIVED RADAR SIGNAL ARE ACCOUNTED FOR

BLOCKAGE AND SHADOWING

(7)

TOTAL AND PARTIAL BLOCKAGE OF CELLS BY OTHER

CELLS IS ACCOUNTED FOR

FOR SINGLE BOUNCE CASE, OCCURS AT LOW GRAZING

N_GLES,

AFFECTS MULTIPLE BOUNCE CASES AT ALL GRAZING

ANGLES

OUTPUTS AVAI I_ABLE

(A)

(B)

(C)

(D)

AVERASE POWER IN RECEIVED SIGNAL

CORRELATION FUNCTIONS AND SPECTRA

AMPLITUDE PROBABILITY DISTRIBUTIONS

EFFECTS OF RECEIVER FILTERING ON (A), (B)OR (C)

197
GROUND- CLUTTER DATABASES

A

B

C

PREPARED FROM AIRPORT OBSTRUCTION CHARTS OBTAINED FROM

NASA- LANGLEY

AIRPORTS ARE: JFK, LA GUARDIA, LOGAN, WILLOW-RUN, MIAMI,

DENVER, NEW ORLEANS, DALLAS, SAN DIEGO, TUCSON, BOEING(SEAI-rLE)

TYPICAL CLUI-FER SOURCES:

SEA. I'IATEP.SURFACES (HARBORS, E.G. JFK, LA GUARDIA, LOGAN)

FRESH WATER SURFACES (LAKES OR RIVERS, E.G. WILLOW-RUN, DENVER)

PAVEMENT SURFACES (ROADS, RUN,lAYS, ALL AIRPORTS)

HILLY TERRAIN (CLIFFS, E.G. BOEING)

SNOW COVERED TERRAIN (ALL AIRPORTS IN WINTER EXCEPT MIAMI,

NEW ORLEANS, TUCSON, SAN DIEGO)

TOWERS, ANTENNAS, BUILDINGS (NEARLY ALL AIRPORTS)

SURROUNDING URBAN STRUCTURES (ALL AIRPORTS NEAR CITY,

E.G. LOGAN, LA GUARDIA, JFK)

198
4

DEVELOPMENT OF ALGORITHMS

FOR TERRAIN FEATURES

(1)

(2)

(3)

(4)

MODELLING - WAVE APPROACH

(A) RIGOROUS FORMULATION BASED ON MAXWELL EQUATIONS

(B) ACCURATELY ACCOUNTS FOR POLARIZATION - BOTH CO-POL

AND CROSS-POL RETURNS

(C) DISADVANTAGES - SOLUTIONS DIFFICULT AIxE)CPU-TIME

INTENSIVE; APPROXIMATIONS REQUIRED (E,G. 1ST AND

2ND ORDER BORN)

RADIATIVE TRANSFER THEORY

(A) PURELY ENERGY - PHASE SUPPRESSED

(B) EASILY ACCOUNTS FOR MULTIPLE SCAI-rERING

(C) FASTER BUT LESS ACCURATE

DISCRETE SCATTERERS - SHORT OR LONG WAVE APPROXIMATIONS;

EXACT SOLUTIONS FOR SIMPLE GEOMETRIES

SURFACE SCATTERING - TWO-SCALE MODEL WITH RANDOM SURFACE

VARIATIONS

199
"r

q_

-LO

-20

o

\

\

\

\

\

INe{ S¢o,J- 13 GH_

Zo

| o

_-lo'

200
wa v'e :a l÷•

W-_e e ¢

.CH g,

¢',_- a',v O"n,

-?c?

_2 °

t ._ ("(,'ef._ /4 eE

-/.]/

-12. d

i

201
To Radar

Direction of em

Wave Propagation

Air Local Angle of

Incidence of em Wave

{ 4-Normal to Facet

Facet

Ocean Surface _.

Capillary Waves

Fig. 2 Geometry of em wave scattering from ocean surface.

ORIGINAL PAGE IS

OF. POOR QU_LLI_

202
#

C_.o0

Fig. 4

g

r T l T • 1

49.75 99.50 149.25 199.00 2q8.75 298.50

VAR X (in meters)

A typical gravl_ wave height profile generated by the computer for

a wind speed of 20 knots directed at a 450 angle with respect to the

x-axis. The x and y axes in the plot represent two orthagonal dlrheightecti°nSof°nthethegravitymean oceanwaves,surface. A different scale is used for the

203
0

0

o

XXx

X

XXX X

X

X

X

XX Vertical Polarization

-- HorizontalPolarization

• Rayleigh Distribution

X

X

X

X

X

Fig. 6.

7

I I l I

-II.LIB -7.1Ll -;).86 l.t13

NORMALIZED AMPLITUDE IN OB

The probability distribution of the backscattered signal envelope,

{the angle of incidence of em wave is 70o; wind speed is 5 knots and

is directed along the x-axis). The ordinate gives the probability

that the backscattered signal envelope will exceed the abscissa.

5.71

204
4L

b

C.A

L;-}

LLJj

o_

'0.00

Fig. 5

ORIGINAL PAGE I_

OF, POOR QUALITY

i:fi;

ii/i iUvv

,1

/!

I

I

I 1 I I

!q. l 7 28.35 q2.52 56.70 70.67 85. Oq

FREOUE_!EjY IN HZ

A typical doppler spectrum of the backscattered field. (Angle of

incidence of microwave (x-band) is 700; wind speed = 20 knots, wind

direction is 450 from the x axis; the incident and scattered fields

are vertically polarized.)

!

99.2

205
m

N

A

V

l,,,,d

a-1

U

°l=mli

g!llllD I

IIMBIE ]

,,JlIFII •

A

m

m

_nml

A

1El

a,1

-gl,-,

o:_ C:D

c: ...1 oom

l..-

m

O CI

..C

_n

(D

PRECEDING PAGE BLANK. NOT FILIV-O

207
IRADAR,,SIMULATION j

Radar Parameters

l Input Data "J Ant. A/C Pos. Scan &Angles Attitude

.

I- Calculate I_ IMIcroburstJ

I Rain Return }- ]Data Base]

i • /

t

I ca! culate I_ , , )ClutterMapl

i

] C_:trenr 1- lDa ta Basel

N,:wI ; •

IRa _ iNoiseiJitter j

. g__i_,j IAdd System I

l ! calculate I

l I I&Q Pulses I _'Q Pulse

Outputs P'ot" J

208
ORTGrNAI2 PAGE IS

.OF POOR QUALITY_

qlb

A

a

j ,(

V

Ill

tL

ID W

O a:

m

,cg

0

0

0

(_) 30nl117v

0

0

LU

,_I

0")

0 0

209
a

I-WM0X

>.

I,-

F- U

tUJ

I1_

ILl 0

m-

(w) 3QN1117V

E

uJUZ

<{

u) a

210

DKIGINAL PAGE 18

_)_ POOR QUALITY
ORIGEWAL PAGE I8

OF. POOR QUALITY

A

v

O

X -

m

W

8

B.

X e_

W

-J

(9

{D

O

211
A

0

..I •

= lD 0

0 0

Z -'

a

i

Z

,<

=E

212

ORIGINAL PAGE IS

OF POOR QUALIT_
I,-

0

(.I

m

A

I0

,,.I

I,I,I

Zi

&l,l

I-,.

m

Z

,(

ORIC]TXrAL PAGE I8

OF POOR QUALITY

E

Q

Z

(/)

Q

213
m

A

¢@

!°

ii

UI

X

h- i

Z

(tu) 301"11117V

A

E

v

U.I

U

Z

r_

214

ORIGINAL PAGE IS

OF POOR QUALITY,
-r

i

Q

/

ORIGINAL PAGE I8

O_ POOR QUALITY.

215
I

I

•,,. ¢=

oE

\

\

\

\

\

\

\

\

\

\

\

\

\

\

\

216
b--

rr" -5

<I_ EL

gZ_

rr" -"c)

Lz_ _

o_

C3r

1,1

__J

EL.

X

LL]

I

0

0

0

0

I

_0

I

@

I

C)

apn_!IdLUV

I

I

I

@

I

aSlnd

#_

©

E

i

E

I

i

217
tAD

c.9

O

m

t

E

m

m

m

m

m

............ 1 I I

I I i

_13 u3 '--

I I

apn_,[IduJv aslnd

218

ORIGINAL PAGE IS

OF POOR QUALITY
_-- C_

<o

!1

I---N

r't"

r'r] II

od

m o3

I z

_- 03

r'r"

n-- E

111 ii

0_ ©

0o _.

4--1

Iq/ x, 0

LLJ _"

u_

0

I

L

m_

I

m _ m m

f

f

• o _. -[__

1

u3 ug

c_ t,3

I !

AAEtG-_3AAOd

219

LQ

I

0 m

r,q

0

m--'---"--- ,

2L

I

uQ

I

C3

I

ORICZ_VA£ PA

.0_' POoR ,__ 0_, lg

"_uAl.,l_p E
<o

II

I-.--N

_0 <.

m_

o_

n,," I z

[D

n,"E

b

0m0

_H

I

,'NL

, I I S I IVM-hi3MOd

J

r

Cxl I 0

0

u") 0

m

0

" I 0I

(DI rj3!

i.-,,-

C) 0

_..1

:>

ii

220
p

0

II

F-N

00<.

c_

0

r_.-w

II

Iz

aq

I--- __

LJ

a"©

_X

©_ A

>

f

Ii

I\i

j

/

\

?

(

I

/

£_

IIII

c)

u3

m

0

o_'_

(_I oI

u_I oI

u3I

C/31

..J

L_J

221
on

<I: II

N

rF-o

0

rF E

i

II I z

cF

n 11

cr_

o5

n_

uO

0

I

J

_ff

ur}

I

u'} u_}

I I

MSCi-_I3MOd

I

o

__1'

I...LI

._

4

4

222
! ! ! ! I

7 . 7 r 7

o

I

EL

U3

b--q

C_

_A

LLA

Ill

LD

Z

<:E

yrI

U

|

!

l U

|

CD Or3 C3

U

II

I

x_r

oJ

cO

O3

¢'_

or3

I

LID

I

.OJ

t.f3

->_

b--.q

2

DA

._J

Ia_J

_r-

(tuft) 99NVtd

223
a._

u-3

H

;C33

i

___J

_LJ_J

Lt_J

_C__9

I I I I I

o° ., °° °° .°

0 I_ _ _ _ I

I I I I t

LID

|

'!

I

|

(w>t) 39NVU

ORIGINAL PAGE /,5.

OF POOR QU_

I

C_

cD

c)

c_

I

C_D

I

C_

I

m

b--q

fz)

....J

LLJ

d

I.U

224
<

6,06

D," II

m>-.

or" .-e_

0

_n.-

o"

cD<

77 o

Ii'

pUw

(

II

>._ o_ n-- k-- -

__J

Lt_l I!

Z

<_

LLJ

o

-,-j

4_

:I Ca. I,,.

bORIG'rNAL PAGE IS

OF PO0,{ QUALITy

/!

i

-.\

!

!

I

I

I

I

I

//

0 0 0

s/w-[_!eOlaA

0

I

[_

tr_

rq

-t'--

,-u_

0

04

I

v_

1

(0

cOd

225
EL

"I" !

--_d

(-_ C3

II

(-/')

i

(D

Lt_J II

>

<

h_A

|_ "

I

!

I

!

I

I

I

I

I

1

1

|

|

I

U__ '

)

m

m

0 0

c,4

0 0 0

I

0

eq

I

-u')

0

I

226 ' ",_:iGINAL PASE IS

OF POOR QUALI_

_%

I

¢-

C_

Pr"
t,

CO)

13.

Z

0

ORIGINAL PAGE IS

DE POOR QUALITy
Q_U_I ONS AND__

RUSS TARG (Lockheed R&D) - I have a general question about

signal to noise ratio. Everybody working in forward looking

remote sensors is concerned about signal to noise ratio. I would

like an idea of the magnitude of the clutter to signal that you

are dealing with and the corollary to that would be in half the

microbursts that we study at least, they are full of water and

the other half they are so called dry microbursts. How is the

algorithm you're developing deal with the so called dry

microbursts and what are the general signal to noise situation

with regard to clutter to return in the two kinds of microbursts

you are studying?

CHARLES BRITT (Research Triangle Inst.) - Let me point out

again that we are not to the point of coming out with signal to

clutter ratios and signal to noise ratios, we are still

developing the simulation and we haven't got good clutter data.

I will make that point again. Maybe in a couple of weeks, when

we get some reasonable clutter data we will be able to answer

some of these questions, but I would not say now. I would

generally say that clutter data is considerably more than the

signal. Does that answer the question?

RUSSELL TARG (Lockheed) - It really didn't answer the

questions. The last time we had a meeting here, six months ago,

people were talking about 60 to 70 db clutter greater than

signal. I wondered if any algorithms were developed? I know you

are working on that to try and do something to filter out the

clutter end obviously what you are working on 50-60 db seems like

quite a deficit, particularly in the favorable case where you are

looking at a wet microburst. We are having to look at both wet

and dry and I know that there is a huge difference in the return

that you get from wet or dry microbursts. And I wondered if the

microwave approach you are looking at deals, at all, with the

reduced signal that you get from the dry case?

CHARLES BRITT (Research Triangle Inst.) - Yes. The signal

level comes from the microburst ntodel that is generated by Doctor

Proctor. He has generated a high level of dbz level initially. I

understand he is developing one at a low dbz level which we will

work with. There will be a threshold where we can't see. That

is what we will find out.

E. BRACALENTE (NASA LaRC) - That 60 or 70 db number you saw

was based on this model. We scanned that radar image, digitized

it and then put in a calibration where the backscatter sigma zero

ran from -5 db to -40 or -50 db depending on the ground target.

And that was the basis. We haven't really got involved in

algorithm development yet. We'll not until we get some real data

and really know what we've got. But obviously there are

4

228
<,,t_jLGINAL PAGE IS

OF, POOR QUALITY

techniques that can be applied.

be looked at.

A lot of filtering schemes will

1

In response to Russell Targs's second question. The

clutter-to-signal (CSR) ratios mentioned at the previous meeting

were in the 50 to 60 db range relative to a 0 dbz signal

reflectivity. This is for the antenna pointed down along the

glide slope and a range gate 5 Km from the a/c, where the main

beam touches the ground. At shorter range gates, under 3 Km, the

CSR falls below 30 db. With a 20 dbz or greater signal, typical

of wet micro-burst, the CSR for the worst case will be below 40

db, and for the shorter ranges below i0 db. These CSR are within

a range that present day radar and filtering designs could

handle. For the dry microbust, where the reflectivity is below

i0 dbz proper antenna pointing, range limiting, higher powers and

higher frequencies may have to be employed. These trade-offs

will be assessed to determine the performance and limitations of

Doppler radars.

PAT ADAMSON (Turbulence Prediction) - At any point have you

addressed the asymmetric cases for an airborne radar? It seems

to me that that is a problem. I don't see it in any of the stuff

that has been put up.

CHARI,ES BRITT (RTI) - We haven't yet. The data bases we

ha __ are symmetrical. The first thing to do is move those off

center and then look at those and then we will get into the

asymmetric cases.

E. BRACALENTE (NASA LaRC) - We just started looking at that

and that is the first model we've got to work with and we will be

looking at all the different cases. Wet, dry, symmetrical, etc_

But we are trying to get the model for the simulation program

developed to the point where we can start looking at all this.

JIM EVANS (MIT Lincoln Lab) - Let me make a couple of

comments. The question of what the reflectivities are to

microburst, I would re_resent, you don't need a simulation

model. There have been enough field measurements run in wet and

dry environments so that if you don't know what the dbz levels

are by now your model will never tell you anything different.

Because people have been measuring them now for 5-6-7 years and

there are probably over i000 microbursts that have been

measured. And I dare say that anybody who claims that a

simulation model is going to improve on the thousands of measured

events is crazy. It is very simple to go through and compute the

signal to noise ratio at X band for the presumed operation. And

i. E. BRACALENTE has asked that the following comments be added_

229
I'm hoping somebody has done--I'm sure John Chisholm has done and

could share that result. If you plug in a typical sigma zero

without getting into great exotic behavior ERIM's existing data

base isn't applicable because, the crazy angles of incidence are

really things like 3 degrees and below. And the sigma zero go up

radically. The case you gave, the grazing angle and the scenario

you have pointed out, is 3 degrees, not i0 degrees. Anybody who

has ever looked at airborne data knows.the cross sections go up

very fast as the grazing angles gets down near 0 and below 5

degrees in particular. My rough guess is if it can't work in an

urban environment people are never going to buy it. Almost every

airport I can imagine has at least one approach or two that are

over an urban environment and I mean houses and so on. Just look

out next time you go into a major airport. So forget all the

other stuff, if you can't work over an urban environment you

probably don't have a viable system.

E. BRACALENTE (NASA LaRC) - That is exactly what we are

doing. The data from ERIM that we are going to be getting, is at

3 degrees.

2

In response to Jim Evans' first comment. The purpose of

the microbust simulation model is not to answer the question of

what reflectivities or windspeeds are in a microbust, or to

improve on the thousands of measured events, but to provide a

high resolution spatiallly distributed data base of windspeeds

and reflectivities representative of a typical microburst. These

models can then be used by e aerodynamicist to evaluate its

effects on a/c performance, and by sensor developers to evaluate

sensor design trade-offs and performance. --- Generally, sigma

zero does not go up as the grazing angle decreases. In fact for

most targets such as runways, grass, water, farm lands, and

forests the sigma zero decreases significantly with decreasing

grazing angle. For urban environments sigma zero tends to be

more constant as a function of grazing angle, with a mean value

around -10db, and decreases slightly with decreasing grazing

angle. Only when the Grazing angle approaches 0 to 1 degree does

sigma zero sometimes increase due to multipath scattering and

specular reflection from the flat sides of buildings. These

extremely low grazing angles will not occur in the range gates

that would be processed in an airborne radar. -- It has never

been suggested that an airborne radar is being developed to work

only in non-urban area around airports. It is because of the

urban environment around most airports that we're obtaining the

ERIM SAR data at low grazing angles. This data will help us

evaluate the severity of the urban clutter and to investigate

radar configurations that may be able to work within this

4

t

2. E. BRACALENTE has asked that the following comments be added.

230
¢

environment.

JIM EVANS - Okay. Let me make a comment. If you take a -i0

db sigma zero (which isn't a reasonable guess) and you work out

the math for i0 kilometers, you are going to find your clutter is

probably 70 or 80 db above your signal. That is just: the w,:_y the

numbers work out, and I think John Chisholm will verify that. At

i0 kilometers I don't think you have a viable system. Not if you

take the simulation model and you believe that the microburst are

only 2 or 300 meters thick and you believe that you h_ve to

function over an urban environment, I don't think you are even in

the ball park. And I'll make that as a simple challenge and _o_

can plug it into the sigma zero numbers and carry them out, John

Chisholm has done that and I'm sure has drawn the same

conclusion.

3

In response to Jim Evans's second comment, f think yoo

will find that the numbers you have given are significantly in

error. Specifically, fo_ an a/c at i0 Km from touchdowp, arid an

altitude of 525 meters, using a 3 deg. beamwidth antenna looking

down the glide slope (-3 deg.) at a 20 dbz reflectiv_ty (a

reasonable number for a wet microburst) and a ground backscatter

sigma zero of -i0 db (a reasonable estimate for urban clutter)

the clutter will be about 45 db above the signal, not 70-80 dbo

(Which agrees approximately with the numbers Jobn Chisholm

co_,puted. See his commel_t which follows.) At the 5 km _:ange

gate, which provides adequate warning time to the pilot, the

clutter is about 26 db above the signal. At shorter ranges and

with proper antenna pointing management the clu_::ter levels can be

reduced significantly further. These lower c]utte_-to-sign_<_i

ratios are well within the limits that present day p_ocesso_s _r_d

radar designs can handle.

OR[GD:rAL pa ¢',_

O?' ...... ...

* OC,v QU_LITy

3. E. BRACALANTE has asked that the following comments be added.

231
#

1 Z

LU

o0

£0.

Z ,,,

0

F- CO

LU .. _j

F-,,, _

a --

z

_a

wow

_ a

za z

m

W

0

Z

DC

0

IJ.

rtLLi

>.

m

a

ILl

I--

0

:D

N88-17626

Z

°RECEDING PAGE BLANK NOT FILI_ED

233
!

lJiaz

LU

v<

I--

LL0

>- <

If) <

n_0wn

',,I

L/I <

r_

Lu

F-U<

n_

F-Z0UI mD

LL0Z0

i--

Q.I

n_U

VI

LUn

0_

F-Z

Ill

UJ

Or

L_

n_

LUUZ<I0><

tnZ<Z0

k-U

LU

LUaW<

LU

nLnZ

WUZ<

r_0

ii

r_" w

a_Z0

k-<J

_,=-=

nl0

u_

Q_

LUUZ0

>-

nl<

2-)

cO

,IYl

F-

-3

SO

ul

LU

nl

ORIGINAL PAGE Tg

OF. POOR QUALITY,, U

kI

kI

U9I nl

(/I U3 LJ Z Z oq< 0 0 _a

F- F- LU U n n Z 0 _

n_ L3

_°_ U_< 'LU

o<

zw0 u.

< is)Uw

234

u_UZO

r¢

I-- U

I..U

_..1

I..,u

b..I >

.<:

I"-

"-rL_

._1I

b_ZO

t--. O

r_<

_..I

u.,I

I--

,<

I--I

._1 O

d'!

m

I-- UI

b_

>-

._.1 <Z<ZO

t-. <

_3

:D

U.I UZ<

ad©

u_

rY

i11

O_

I-.

ILl UZ0U

Z©UZ0U
f

Z

ill

O

ORIGINAL PAGE [_

0]_ POOR QUALITY

235
00

I--- Z

ILl

aDZ

••

oW

00I

Cl Z

O

rY"

i.I.

FL) O

__l

ILl >nZ

u. o

09.

F-" Z

U.I ZOoO

_.! <O

FCC

Ill aZ<

E

CI Z co

Cl I-- < I--

LUD

7-O

111 l--

CC"

D

CD rr < O W CC @

CC

ILl >OO

Ill

CCZI

I--

CC

111

7-

F-"

rr

ILl OZ

Cl O<

LUN

O) <

"1-

(3_

ILl

I.U

F-- <

CC

CC<

_.l <

C3Z<

C0 DZO

...I

7"

I--

ILl

I--

__i <

I.U

rY- EaZOn

U) W

nc

"lF- <

ii

Ll_ O

ILl <

I-- DZZD

CC

F- <

D_

7-

L) <O

nIl. <

n- O

F-- ZO@

00Zo

F-

£3ZO

C.)

cC

ILl

._1

C.) aZZ<

CC

7-

I-- O

O3 ZW

FCC

ILl nO

W- E

ILl ZO

17" Z

111

u_

n-O

n-Z

ILl 0ZZ

Ill ZZ

7-<

_1W

rr"

U.!

b- <

17"

I11 no

236
u

COZ

UJ

ILl

n-m0

UJ

.-I

.<0

_J

-t- O

uJ

[JJ

I<Z

UJ

FE

tO0

UJZ

n"ZmZ

LU

E

tO0Z0i

I--

=)

_10

O_

ILl

rr

LUZ

rr

(oE

_J

UJ<X0

rrnn<Z0

_J0

CO

uJ

rrm00

..J W>

237

00

I..-

ILl

ILl 0Z

r_
0

Z

,<

,.-- -rE

::::L C)

0 _ '_

U m

<

-J E Z

_ tlJ

,._ v

I

<

_- X

_ m ,-

iE

V

1,1..

o

(J

> z _

238
v

(J

I

uJZ

..I---

_uJ

Ez

ORIGINAL PAGE IS

O_ POOR QUALIT_

E

I I

[BP,I _iNS

239
E

@

240

0

,--,

13

!-0Z0u

I--

r,,,

co LLI m0Z0

=. I- • I <Z

u3

o I-

'-0

"t"

_q

LU

.J

oZ

(,/3

¢'N

t,__T_
(s/ua) (^)_ _10_1_13 A.LIDO-13A

E

241
uz\ o.=

z_ _LL -1 ._0.

3ct- "-"t_:

_-_ _. , _ II

_-z II

wm I/ _

I I I I I -,.I.

(s;_l) ,_11:30"13A C]NIMQV3H

242
O

1 rr

COl/ 1

E-J

rr

l--

r_

<

<

r_

>-

r_

<

Z

-3

w

r_

eL,

ORIGINAL PAGE IS

_l_ POOR QUALITY,

>-

m

U

O

.3

t_

E

E

o

I

I

I

I

!

l

\

\

%

l

/

_s

'br¢

_CO _

e,"

_l'_ 0lJ( °

I

I

{s/w] JklIDO7:IA ONIM 7Vl(IV_l

;mu_

ww _U

OQ

243

t_

t_

E

LU

==" rO

Z

0

0

¢"N

I
< < u_ w o "-

n,.' C3 _ _ ,- o

(,j r,"

I--'1"Wrn OC N< <'-I _,..

0 _: <

"r" w _ "' C_

0 "r z I.-

F_ u_ l.U u. ,,, 0.._=

> 0

,,,=. _z > ,,,_u

0 0 w 0

z ku "_ _c

I-- < _ L.) w

>-=, _ , I.- ,( _ z ,,=:

o,,, _'< 8_° _"

z < _- = o

9z , ,.,< -r r_ ..J Z

_ LI .. r_ < <

Z u-, U

.0 "r "r

_," uJ E3 Z

o _ " " " _, _ _=

>. ,,( _ _ "(

_o o< _ <_-a

_ n,,' Z w _ w _ Z

-- w ,,( "r Z _" _ _

a>= _-< _= <_

244
4

Z

i

v

ORIGINAL PAGE IS

OF, POOR QUAEXT_

Z

<

E

z

<

n, ,_

M

I I

0

0

0

___'"\'\'iT'\\" "\, \\\,', \\,

..J

<

U'-"

m try-..

tO'*"*

>,_.

I I I l

0 0 0 0

0 0 0 0

0 0 0 0

I I I I

I

I

_a

I I

0 0

I I

v

v

%

U

-ruJ

ZL_

<Z

245
(/)

D:

"!":3

om

u.O

0

p.

f

®

Q

r

Q

®

Iii1

..J

<

LU

I/1

I

z

i | i J I I

o° _ o oo

o o o o :

I I I I

--I I I [ t I I

,,.p

z

i

o

J l I I I

S o S

1

0

U

Ill

.J

I11

5

a.

Q

246

UJ

o

%

i i

=--o-i, ".

I--

ill

J I I I

®

IM

(.11-

mE

mD

_D

I

o o o ,,, ,, _ o _ .

_0 I I I <z

.-1

S

OR/GINAL PAGE IS

D]_ POOR QUALITY

v
i

Z

I

O_

ILl

a

-3

O

Z

3=

O

LLI

I

O

V-

¢L

O

ORIGINPfL PAGE IS

OF. POOR QUALITX]

247

t

1

0m

I-- 0

II! ==

I-- I_1

wo

_Z

wO

--Z

rail

--!

I-Z

ILl

ILl 0mZ0

LU

I--

13Z

UJ Z

rr0

LI.

rr

LIJ

O.

249

U.! m

LIJ

n"

n" 0

nt"

I,LI

I"

GI m

OC

LIJ

I-- Z

1.1.1

I',, .T.

coo 01

v-OC I

OC

U,l>- m 1,1.1

O,-S

OZ

0'_

..i Z

dZ

toO. mn o

i-o

Om

-1 LU_

.1-¢_m

WW

ff) Ul

W_

00

--I

q

l,

ILU

(/)

Z LU 0 m

-- (/)

IIII ,,=

I- u.I_

mOO

C:IZ --

II:,_z

WOw _

a

Z_Z

--Z<

<m

_J

WZ

<1:

I:1: 0

ll

niii

O.

LLI m

uJ

el: <

I:1:

(50

0:

I:1.

D:

i11

lC] m

251

I:Z:

ILl

I-- Z

LU

I_ :Z::

0)

_wI

r_.LU

I.U_-

ml.u

O...J

OZ

O<

..I <

t/) <Z

<

I..-

_.1

..I

UJ

t/)

:::)

Z

m

I_0,

I-0

O_

_,1

!.1.1_1 mm

,<_

1,1.1!_1

t,t_ I.U

I,i.1'I"

L) 0

==1
v<

I'-

LL0

>-

n, <

U_ <

ID0

n,

o.

v}<

UA

I-U<

a_

F-Z0UI

cO

u.0Z0

Fa.mU

Ill W

oOZ

I,i

uJ

(:7

111

ty

i,i Uza0<

r_ZZ0

F- U

i,i

Fr_

i,i

-rQZ

111 Uz0

I.I.

ii1

I:Lz0

I-/0

ii

Iiii U70Ui I

>-

:E

:D

Ill

I/I

_l>-

_Z

Z0UZ

I.I. 0Z

ILl

252

m

I'-

u3I

oqz0M

I-- n0

0C<

.J

rN

0U

U

I-

::DI

u3

n,

ILl

U3 <

_1

LU

LU<

LL

n_

UZ0

n,'

I--- U

LLI

.J

LU

ILl ><

I-.

"1-

_0

,..JI

u3Z0

lb. 0

n,, <

E3

.J

l.U

I-- <

IbqI

E3

_10

m

I-- UI N

>-

._1 <Zz0

_J

i,i Z<

r_0

i,

r_

i,i n

F- Z0

Z0m/UZ0U

w
N88_17627

AIRBORNEDOPPLERLIDARDETECTIONOFWINDSHEAR

RESULTSOF PERFORMANCE ANALYSIS

NASALaRCILOCKHEEDPO_SEPAK8630A

OCTOBER22-9.3,1087

COHERENTTECHNOLOGIES, INC.

R. MILTONHUFFAKER

253
0

4muo

q..

amid

(J

0

O

ii........

o • • • • • • • • • • • o • • o

o • • • • • • • • • • • o • o •

• • • • • • • • • • • • • • • o

o • • • • • • • • • • • • Q e 0

0 • • • • • • • • • • • 4 9 4 Q

e • • • • • • • • • • • • 4 • t

4 e • • • • • • • • • • o o _ • %

_|O0 • .o o e e ego O_o _

ooo . ..o.o.ee SS*o_

ill • ettSti||Jtt_#_l

I I I • I • • • _ • • • • • _ i _ _ Id

/

t e I o o o • • • o B P P I 0 F I J _ _ _

! ! e e e e • • . w e e B I _ | | t • • _

! ! e _ e e _ e . e e e e o e e _ _ _ _ • |

t e O O • 0 • • • • • • • • • • • _ _ _ p

e 0 0 • e • • • • • • • • • • • • o o _ •

t 0 0 0 o e • • • • • • • • • • • • o • •

0 0 • e • o • • • • • • • • • • • • • • •

0 O • o o • • • • • • • • • • • • • • • •

0 e o e • • • • • • • • • • • • • • • • •

e 0 • • • e • • • • • • • • • • • • • • •

e • • • • • • • • • • • • • • • • • • • •

e o • • o e • • • • • • • • • • • • • o 4

: : ; " ' "i ...... n...... ," " "

lull T_OlOH

q_

m

Q

254
AIRBORNEWINDSHEAR

LIDARCOMPUTERSIMULATION

READINPUTPARAMETERS

SET UP MEASUREMENT GEOMETRY

Z,O,q_,AR

REALIZATIONLOOP

SHOTLOOP

RANGEGATELOOP

CALCULATE_ (AFCLHITRAN)

INTERPOLATE_, C_

n

CALCULATEE {RECEIVEDPOWER}

MULTIPLYBY SRF

SPECKLE,REFRACTIVETURBULENCE

MISMATCH

, PHASEFRONT

INCOHERENTSAMPLELOOP

IF C_/2 <_R)(USESA_IER FOR ALL)

255
APPLYEXPONENTIALFUCTUATIONTOE {POWER}

X SRF

SPECKLEDOXINATEDPDF

N CALCULATE.WIDEAND NARROWBANDSNR

Bw = 4 Vmax/k; Bn = lit

INTERPOLATERUERADIALVELOCITYFROM

MICROBURST, V

r

A

CALCULATEESTIMATEDVELOCITYV

r

CONVOLVEV WITHGAUSSIANTEMPORAL

r

PULSE

CALCULATEVELOCITYWIDTH

SECONDMOMENT

CALCULATECRAMER-RAOE {VEL. ERROR}= _v

USESNR ANDVEL. WIDTH

W

CHECKIF _ < V THRESHOLD?

v max

IF NO, THROWESTIMATEAWAY

256
IF YES, GENERATEA CAUSSIANR.V. VE

MEAN= O, STDDEV=

V

¢

, A

CALCULATEVm= Vr + VE

COMPLETEINCOHERENTSAMPLELOOP

CALCULATEMEDIANV and snr

Ill

(IF EVErtNUMBER,AVE.TWOIN MIDDLE)

COMPLETERANGEGATELOOP

COMPLETESHOTLOOP

CALCULATE

COMPLETEREALIZATIONLOOP

CALCULATEcT_

vE

257
:3

E

bO

t_

(9

..C:

bO

(jq/u!)oloJu!o_

C

0

|

258
AIRBORNE WINDSHEAR LIDAR BASE CASE PARAMETERS

(CO_ LASER)

ATMOSPHERIC PARAMETERS

LaRC PROVIDED MICROBURST FIELDS

NO RAINp HAIL, CLOUDS

MID-LATITUDE SUMMER MODEL ATMOSPHERE

AEROSOL BACKSCATTER COEFFICIENT _ = 5 x 10 -8 (m °1

MODIFIED NOAA-WPL-37 C 2 PROFILE

n

.st -1 )

LASER PARAMETERS

WAVELENGTH [CO 2 10P(20)] _ = 10.591 _m

PULSE ENERGY = 5 ma

OVERALL OPTICAL EFFICIENCY = .1

PULSE DURATION = 2 _s

300 m RANGE RESOLUTION

10 PULSES AVERAGED

15 cm TELESCOPE DIAMETER (e -2 INTENSITY)

3 km FOCAL RANGE

AIRCRAFT POSITION AND LIDAR ANGLE PARAMETERS

4 km TO CENTER OF MICROBURST (ON-AXIS)

500 m HEIGHT ABOVE GROUND LEVEL

-30 LIDAR ELEVATION POINTING ANGLE

t

259
AIRBORNE WINDSHEAR LIDAR BASE CASE PARAMETERS

(Ho:YAG LASER)

ATMOSPHERIC PARAMETERS

LaRC PROVIDED MICROBURST WIND FIELD

NO RAIN, HAIL, CLOUDS

MID-LATITUDE SUMMER MODEL ATMOSPHERE

AEROSOL BACKSCATTER COEFFICIENT p =

MODIFIELD NOAA-NPL-37 C 2 PROFILE

n

1.25 x 10 -6 (m -1-st -1)

LASER PARAMETERS

WAVELENGTH [Ho:YAG] _ = 2.0913 _m

PULSE ENERGY = 5 m3

OVERALL OPTICAL EFFICIENCY = .2

PULSE DURATION = .5_s (4 SAMPLES AVERAGED INCOHERENTLY OVER 2 ps)

300 m RANGE RESOLUTION

10 PULSES AVERAGED

15 cm TELESCOPE DIAMETER (e -2 INTENSITY)

3 km FOCAL RANGE

AIRCRAFT POSITION AND LIDAR ANGLE PARAMETERS

4 km TO CENTER OF MICROBURST

500 m HEIGHT ABOVE GROUND LEVEL

-3 ° LIDAR ELEVATION POINTING ANGLE

260
CO_ SYSTEMATIC PARAMETRIC ANALYSIS

Step 1: OPTIMIZE PULSE DURATION/RANGE RESOLUTION:

.5 _sp 1 _sp 2 _s, 3 _s_ 5 _sp & _s

(75m)p (150m), (300m), (450m)_ (750m)_ (?OOm)

Step 2: EXAMINE NUMBER OF SHOTS: lm 2_ 5, 10_ 50p 100

Step 3: EXAMINE FOCUSING: f = 3 km, T = m

Step 4: EXAMINE OPTICAL DIAMETER: D = 7.5 cm, 15 cm_ 20 cm

Step 5: EXAMINE REFRACTIVE TURBULENCE EFFECTS: C 2 C 2 x 10

n' n

Step & : EXAMINE PULSE ENERGIES:

l_J, 50_J, .5mJ9 5mJp lOmJ, 15mJ, 20mJ_ lOOmJ

Step 7: EXAMINE AEROSOL BACKSCATTER EFFECTS:

= 5 x 10 -8 10 -8, 10 -9 10 -10 10 -11 (m-l.sr -1)

Step 8: EXAMINE WET MICROBURST

Step 9 : EXAMINE AIRCRAFT POSITION: 4, 3, 2_ 1 km FROM CENTER

TAKEOFF PROFILES

OFF-AXIS ENCOUNTERS

Step 10:

Step 11:

EXAMINE AZIMUTHAL SCAN: ENCOMPASS ENTIRE WIND FIELD IN

A 2-DIM PLANE AT 5 ° INCREMENTS

MULTIPLE REALIZATIONS

261
EE_

.<t::

:..1

13:::

LLI

:E

Or)

LL!

Z

0

8

t

01- St- I/,,-

E

LLI

rd.9

Z

.,..1::

i1

(8P)NOIIOI",IIIX:I _llVMY3-1:3,kVM-_

262
<(

[Z:

Z

-- <I:

,.,rY

Ld

Z

O_

©

O0

O_

I O

Ol _ 0 _- OL- St- 0_-

(s/w),LI_IgO-13A CINIM-IVlClV_l

263
FF

<

__J

E_

<

LLJ

OO

I,I

Z

O

CO

E_

I I

It

,I ! ! I

\ I' I

\

G- Ol- _L- 0_-

E

V

W

0

Z

<

6

(S/W)AZI007-4A GNIM7VICIV_I

264
4

0£

<

_J

0£

Or}

Z

W

Z

0

rn

n-i_

I I I, I I I

(s/m)_0_3 _LlOO33ACINIM03HFISW_I_

W

" C9

Z

o

265
9

I I §I I I I /_ ® ..

(BP)3SION-OI-qVN91S

266
E_

Or)

Z

LLJ

Z

C__

©

FTn

n<_

O_

I I I I I

_I Ol _ 0 S- 01- _I-

(s/w)kLiOOq3AGNIMqVIGV_

267
<

r-q

__J

<

W

EE

O0

D

Z

W

Z

C_

0

CO

nI

I I I

I I I I I

o

E

W

Z

<

nI

(s/w) A.LIOO-BACINIM-iVlCIVN

268
E_

<C

J

__J

<C

Iii

(7}

Z

Ii1

Z

n/

0

r-lq

OC

B_

I I I ! I, I I

+I Ol l_ 0 +- Of- 91- 0_

(s//m) ,kJ.130-13ACINIMqVICIV !

269
0:2

<

dE)

O_

<

LO

EE

O0

Ld

Z

0

0]

O_

m

(s/w) ,kllOOq3ACINIt_9VlCNN

270
<

D

l.l....-=l

_._I

CK

<

b2

I

O0

Z

1 I I

%

LLJ

2:_

0 /

(SP)3SION-OI-]VN91S

271
fl Ol I_ II f- I1- fl-

(s/w) _lOOl3AONIM7VIGV_

-s
4

II

E

1

(SP)3SION-O±-7VNOIS

273
[_ILL

<C

E3

___1

<C

bJ

I

(./3

1,1

Z

0

133

_t Ot _ 0 _- Of- m

(s/w)LLIOO-I-qA GNIM-lVLGVa

274
EK

<_

n

rt"

<E

L_LJ

ZE

O0

Z

I!!

Z

EE

0

m

rid_

i I I

o

M

8

O_

I I I ! I I i

fl Ol _ 0 S- 01- _1-

1

E

LLJ

(9

Z

,<

n-"

(s/w) _IDOTqAC]NIMqVIC]V_]

275
<

__J

W

Z

0

Ol

' i I i I I I I

0

o

m

w

II

m

! I, I !. I I I i_ i

6 9 L 9 _ f l: _ 1

--U

Z

I

,q

(s/w)._o_3 ,U_lOO13A

276
E_

<_

_J

OF)

I,I

Z

0

m

Otr

I i i 1

o

-- II

_ f_i

1 ! !

E

LLI

0

Z

<

02

(EIP)3SION-OI-7VNOIS

277
E_

<_

r-_

w

ZE

or)

n

Z

w

Z

O

m

[z:

I

E

W

Z

<_

E_

(SP)3Sl0N-01-qVNOlS

278
.<

_J

.<

W

(/)

W

Z

O

I-D

I i i

i i I I I I

Ol _ O _- Ol- _;lu

E

W

Z

<

n_

(s/uJ)LU0073AONIMqvlav'a

279
0£

E_

LO

I

Z

W

Z

0

03

Ot _ 0 _- 01- Si- OrE

V

m

Z

nl

(s/w) £1_IDO73ACINIM7VICIV_I

280
SUPI'IARY OF PERFORMANCE

(I_ARCMICROBURSTMODEL,11:00MIN,)

1 20 MJ C02_LIDAR LINE-OF-SIGHT WIND VELOCITY ERROR <I M/S TO 8 KM IN

THE DRY MICROBURST TEST CASE,

, 5 rIJ Ho:YAG LIDAR LINE-OF-SIGHT WIND VELOCITY ERROR < ,5 M/S TO 8 KM

IN THE DRY MICROBURST TEST CASE,

3, 5 MJ C0,2 I_IDAR PENETRATES TO WITHIN I KM OF WET MICROBURST CENTER,

4, 5MJHo:YAGPENETRATES TO WITHIN ,5 KM OF WET MICROBURST CENTER,

11 P_OTH C02 (100 M J) AND Ho:YAG (10 MJ) PERFORM WELL TO 3 KM OPERATING

OUTSIDE THE BOUNDARY LAYER WHERE:

PETA (C02) = S x 10-11 M -1 ' SR-1

BETA (!Io:Y,_G)= 1,25 x I0-9 M -I ' SR-1

ii

,5, LIDAR PERFORmaNCE IN WET MICROBURST r4ODEL DOES NOT IMPROVE SIGNIFICANTLY

WITH REASONABLE INCREASES IN LIDAR PARAMETERS,

281
CONCLUSIONS

1 BOTHCO2 ArIDHo:YAG,_ESHO_ FEASIBLEFORAIRBORNE!'_INDSHEARDETECTION

FORDRYMICROBURSTS!'IITHLIMITEDPERFORMANCEINI'IETMICROBIJRSTS.

2. Ho:YAGPERFORMSBEITERTHANCO2 FORA SETOF IDENTICALLIDARP_S.

3. THESERESULTSAREQU#LIFIEDBYTHELIMITEDNUMBEROF TESTCASES.

282'
N88- 17628

A PRESENTAT ION TO

THE F IRST COMBINED MANUFACTURERS " AND

TECHNOLOGY AIRBORNE WIND SHEAR REVIEW

MEET ING

INFRARED

LOW--LEVEL WIND

WORK

SHEAR

PAT ADAMSON

OCTOBER 22 , 1987

t

TURBULENCE PREDICT ION SYSTEMS

4876 STERLING DRIVE

BOULDER , CO 80301

(3 03 ) 443--8 157

283
ORIGINAL PAGE IS

OF, POOR QUALITY

Pat Adamson

Turbulence Prediction Systems

Bou]der, Co] orado

This presentation contaD_s rL,_ults of field experiments for detection of

C]ear Air Turbu]cnce and I,ow I,ew'] Wind Shear utilizing an infrared airborne

system. The hits, misses and nuisance alarms score and presented for the

encounters. The infrared spatial resolution technique is exp]ained and

graphs aro presented.

The popular index of aircraft hazard CF -wx

g

templ,rature sensor.

_S) is developed for a remote

284
THE_J_._OBLEM

-- WIND SHEAR

- I accident _er _BO00_O00 T * L _A

1 T ÷ L @B

-- SOURCES OF WIND

- downburetm

- mlcroburets

-- DURATION _C

- severe w_nd_

- li_ _p_n _

SIZE COLUMN _D

- 4km or

-- EFFECTIVE

o

-- DI

B

-- MICROBURSTS

1 mtrong mhemr per 65@000

SHEAR

2 to

to 15

2.5 _ile_

DIAEETER OF

4 minutes

_inu_es

OUTFLOW _C@ P

) 2 x coIumn diameter

_FERENTIAL VELOCITY ACROSS BURST

> 56 knots average

OFTEN HAS

_C

LATERAL MOTION

_EFERENCE _

A R . Bowlem NASA Langley; FAA/NABA

Alrborne Predlctlve Meetlng ; Feb 198_

B Uary--Durham NASA Langley; AIAA 22nd

Aerospace Sc_lnca_ _eetlng; Jan 1984

C McCarthy--Sera_tn NCAR; Weatherwtle_

Jun_ 1984

D Fu3its University o_ Ch_cago$ __

DO_NBUNST M£crobur_t mnd M_croburat •

TURBULENCE _REDICTION

285

SYSTEMS
FAA W ][ ND SHEAR PLAN

--E X CELLENT PROGRAM

--TRA I N I NG

--GROUND SENSORS

--A I RBORNE SENSORS

--SECT I ON 5 . 3

THE ELEMENTS THAT CAN I MPROVE THE

FL I GHT CREW " S AB I L I TY TO REL I ABLY

DETECT AND AVO I D HAZARDOUS W I ND

SHEAR INCLUDE :

THE DEVELOPMENT OF

LOOK I NG W I ND SHEAR

A I RCRAFT .

FORWARD--

SENSORS FOR p

THE I MPROVED UT

I NTEGRAT I ON OF

SENSORS .

ILI ZAT ION AND

PRESENT--POS I T I Oh

REFERENCE: "INTEGRATED FAA WIND SHEAR PROGRAM PLAN"; U.S.

DEPARTMENT OF TRANSPORTATION; FEDERAL AVIATION

ADMINISTRATION; APRIL 1987; DOT/FAA/DL-87/I; DOTlFAA/VS-8711;

DOT/FAA/AT-87/1. ,J

TURBULENCE PRED I CT I ON SYSTEMS

286
REMOTE SENSING

VELOCITY

TECHN I OUES FOR

ARE NO PANACEA

WIND

,ORIGINAL PAGE IS

DN POOR QUALITy

--ALL REMOVE SENSORS ]r NFER

TABLE 4 LISTS SOME ADVANTAGES AND DISADVANTAGES OF THE

REMOTE-SENSING TECHNIQUES FOR WIND. IN GENERAL, LONG-RANGE

MEASUREMENTS REQUIRE RADAR, AND SHORT-RANGE APPLICATIONS USE

LIDAR OR SODAR DEPENDING ON WHETHER SPATIAL RESOLUTION OR LOW

COST IS A PRIMARY CRITERION FOR SELECTION. FOR SOME

REQUIREMENTS, SUCH AS A LOW-COST SENSOR FOR AIRCRAFT USE:

THERE MAY NOT BE AT PRESENT A SUITABLE REMOTE-SENSING

TECHNIQUE. (Emphasis aOOed)

TABLE 4

Techniques for Velocity Measurement

Sodar

Radar

Lklar

• Advantaile_ l_advanta_es

Bistatic signal strength depends on turbulent microstrudure

Corn7 .ratively inexpensive

Long range with appropriate tracers

._-D vector fields available with multiple sensors

Vcr'y narrow beam widths

conservative tracers

Flov, tracers no/ uniformly distributed: i.e.. sometimes only senses ,,.."

in special layers

Sensitive to noise From precipitation, high wind. and vehicles

Systems comparatively large and expensive

Anlenna side lobes hmit usefulness close to the ground

Clear-air targets nonconservative (e.g.. temperature fluctuations) and

reqmre high transmitter power

Possible danger Io eyes

Beam attenuated by cloud and fog

REFERENCE: "A COMPARATIVE OVERVIEW OF ACTIVE REMOTE-SENSING

TECHNIQUES"; BY R. L. SCHWIESOW; IN D. H. LENSCHOW, EDIT.

PROBING THE ATMOSPHERIC BOUNDARY LAYER_ 1986; AMERICAN

METEOROLOGICAL SOCIETY; P. 135.

TURBULENCE PRED I CT I ON SYSTEMS

o.

287
A I RBORNE SENSORS ARE NEEDED

I SLAND CONCEPT

--A I RCRAFT CAN TAKE CARE OF ITSELF

J.

MANY

SOPH I ST I CATED EQU I PMENT

--CASPER , WYOM I NG

--GREENSBOROUGH ,

--FARM I NGTON , NEW

A I RPORTS W ILL NEVER HAVE ENOUGH

NORTH CAROL I NA

ME X I CO

I NFORMAT I ON

A I R CREW

HAS M I N I MAL L I NKAGE TO

TURBULENCE PRED 2 CT 2 ON SYSTEMS

288
HISTORICAL CAT RESEARCH _ESULTS

NASA LEAR -- MOLETRON --

NASA C-- 14 I A -- BARNES --

NASA CV 990 -- ADAMSON --

1979

1979

1979

TEST PROTOCOL :

A HIT IF THE ALARM SOUNDS AND

SHEAR OF GREATER THAN 0 . 2 G

ACCELERATION WAS ENCOUNTERED p

OTHERWISE A MISS

A

_ESEA RCH RESULTS : 700 HOURS

WITH MOLECTRON /BARNES

247 ENCOUNTERS

MISSED ENCOUNTERS

NUISANCE ALARMS

RADIOMMETER

84 . 62_ H I TS

I 5 _ 38_

i 4 . 00_

WITH ADAMSON RESEARCH

119 ENCOUNTERS

MISSED ENCOUNTERS

NUISANCE ALARMS

INSTRUMENT

98 . 32_ H ITS

I . 6_

8 . 51_

ADVANCE WARN I NG RESULTS : 700 HOURS

AVERAGE WARN I NG .4 MINUTES

REFERENCE: "FINAL STATISTICAL REPORT ON AVIATION SAFETY

TECHNOLOGY (IN-FLIGHT DETECTION AND PREDICTION OF CLEAR AIR

TURBULENCE)"; BY LOIS STEARNS AND VALERIE NOGAY, NOAA; FOR NASA

AMES RESEARCH CENTER; DECEMBER 1, 1979.

TURBULENCE PREDICTION BYSTEI_S

289
F _x

g

hor iz onta 1

component

v_

AS

vertica i

component

4

|

Reference :

R.A. Greene , Safe

Corp; Journal of

Flight Instrument

Aircraft; 12/79 .

R. Bowles , NASA Langley; FAA/NASA

Airborne Predictive Meeting; 2/24--25/87

Definitions:

wx = kts /s ec --

g = kts /s ec --

vw = kts

AS = kts

horizontal wind rate

gravity

vertical wind velocity

air speed

Sign

_X

VW

Convent ion :

kts /sec when tailwind

kts when downdraft

4

TURBULENCE PREDICT ION SYSTEMS

290 :"..... :_AL PAGE IS

05"Poor QUALI_
I

!

SOUTHWEST 737-300 IN.-SERViCE DATA

III I _R r' - ._ _ _ II

ORIGINAL PAGE IS

DE, POOR QUAL,IT_ _,

MO

.20 .15 .10 .05 0 -.05 -.10

H-_TIDOWNDRAFT F

-.15 -.20

T-_H/UPDRAFT

NO WIND SHEARBY PILOTS EVENTS REPORTED l

INDUSTRY REVIEH OF FORWARD I.OOKTN(; S_2SOP, TECtiNOLUGY FOR DETECTION OF _IND SHEAR

NASA L¢mgley Research Center 24-25 Feb. 1987, Roland L. Bowles

291
F--

<K

D

(,,-_

°-._.

-=:-:-__:

°_--°

+::]::i

.--__+

ILl

t?'.-'

11"I

.,1-"

l.Y.l

IF

C,I

c:$

I

IUC) +o

•_ +

F - -. -. -. _ -.'

• +i .- =

l I I I I

_J

0

0

0

,,LO,I_ nO=Jl_L:l

292

• .

+. :+.+u-J+.L,,,TA.+,_,9AgE iS

.O+E __OOR QUALITY
__TORIC_L LLWS _ESEARC,_R_SULT_

NASA LEAR

NASA B57B

-- 1978

-- JAWS

CALIFORNIA

-- 1982 DENVER.

TEST PROTOCOL =

A NIT IF THE ALARM SOUNDS AND A

VERTICAL SHEAR GREATER THAN O. I

SEC -I ( =I0 KNOTS /i00 FEET) WAS

ENCOUNTEREDp OTHERWISE A MISS

REFERENCE: SNYDER

CO

RESEARCH RESULTS=

42 ENCOUNTERS

MISSED ENCOUNTERS

NUI. SANCE ALARMS

I O0 - O_

0

0

300 HOURS

HITS

ADVANCE WARNING RESULTS=

MINIMUM

AVERAGE

MAXIMUM

WARNING

WARNING

WARNING

14

46

68

SECONDS

SECONDS

SECONDS

ORIGINAL PAGE IS

OF POOR QUALITY.

REFERENCE: "APPLICATION OF INFRARED RADIOMETERS FOR AIRBORNE DETECTION

OF CLEAR AIR TURBULENCE AND LOW LEVEL WIND SHEAR"; BY P.M. KUHN; FINAL

REPORT DECEMBER 31, 1982 - MARCH 31, 1985.

"ANALOG STUDY OF THE LONGITUDINAL RESPONSE OF A SWEPT-WIND TRANSPORT

AIRPLANE TO WIND SHEAR AND SUSTAINED GUSTS DURING LANDING APPROACH";

BY C.T. SNYDER, NASA AMES RESEARCH CENTER; NASA TN D4477; 1968.

TURBULENCE PREDICTION SYSTEMS

293
NASA B57B

CESSNA :;'07

JAWS -- 1982 DENVER.

-- 1985 HUNTSVILLE.

CO

AL

TEST PROTOCOL:

A HIT IF THE ALARM SOUNDS AND A

VERTICAL SHEAR OF GREATER THAN

- 15 SEC -1 (15 KNOTS /100 FEET)

WAS ENCOUNTERED. OTHERWISE A MISS

A SUCCESSFUL PREDICTION REOUIRED

AN ADVANCE WARNING OF GREATER

THAN 40 SECONDS

RESEARCH RESULTS: 19

8 ENCOUNTERS

MISSED ENCOUNTERS

NUISANCE ALARMS

TRACTS FLOWN

75_0% HITS

25 - O_ (2(40S)

4

_DVANCE WARNING RESULTS :

MINIMUM

AVERAGE

WARNING

WARNING

5

32

SECONDS

SECONDS

REFERENCE: "'AIRBORNE INFRARED WIND SHEAR DETECTOR PERFORNANCE IN RAIN

OBSCURATION": BY P.N. KUHN AND P.C. 5INCLAIR, ARIS, INC.; PAPER

PRESENTED AT AIAA MEETXNG JANUARY 18, 1987: RENO, NEVADA.

TURBULENCE PREDICTION SYSTEMS

4

294

ORIGINAL PAGE IS

DE _.00R .QUALIT.Y
INFRAKEt) SENSING "['ECItNIQUE

ORIGINAL FAGE IS

OF POOR QUALITZ

, I I I I I I

I ,

I I I

! I . ,

• * I I ,

' I *

I I

I *

, , i I I

!

I

o I | I

I °

I ' I

I I

! I

! !

' I

KECE]'VEIl,

295
"l'llq E TO

_cou.t_ ,, ,", _,,

(s_co._s) s, o

I II II II

Alcr_o

TPS'sINF_E_LLWSA_VANC_

, , , , l, lq i

ORIGINAL PAGE _

DiE IX)OR QUALITY

_RNIr_ DIAG._M

296
UNIFORM D ISTRII)UTED

OR[oFfAL PAGE I8

.0_ POOR QUALITy.

INFRARED IS ABSORBED

DISTRIBUTED GASES AS

WAVE LENGTH Wowe _u_bev ,tin .t

/

/

• . . • .

4"_5 5 0

J

I

I

,

L

_J

v

• t j , t . ,

• 7 •

I

I

COz._xG.C,_4 e_a CO

I

|

l

]E_Y TH n=" UNZ_ORN

A FUNCTION OIL _

r

I

• oO i_ IZ

Wglwql Jar_0 T_, JJ. _

(#)

800 1tO0 tl_O

_.1 ,,.j _, I .. t . . . I , ,

I

I

n

/\ i _

i

_3 _4 IS

_SO

1 "1

OIJto lit OOq

il i,:

o,o_o

/

!1

, . I

NOTE: TRANSMITTANCE/KILOMETER

FOR EX^MP_E;

6_ 13 . 5 MICRONS

TRANSMITTANCE -- - 60/KM

5 KM

TRANSMITTANCE -- ( . 60) -5 -- 7. 8_

REFERENCE: HANDBOOK OF OPTICS; WALTER G. DRISCOLL, EDITOR;

McGRAW-HILL BOOK COMPANY; 1978; FIGURE i7, PAGE 14-43.

297
aadiative transfer Theory via the

transfer equation (RTE) drmonstrates that a

"hortgomtal]y looking" infrared (IR) radloleter

Cln easily detect telnperature changes as small

as 0.3C at a distance of 10 km. The 1l piss

band for such observations is the carbon dioxide

(C02) band. In this tnstance we refer to transfer calculations in the 695 to 725 cm -1 pass .

band.

The RT[ espres_rn the radiant

e_lsslon received throuSh s horizontal path in

the at=ms,here at an IR detector through a

filter. 0(v). as

. _(u(C02))

- - J J s(v.T)¢(v) _: dz dz). (2)

V Z

_here N and B are radiance (w co -2 ar -I) ; _ is

wave nL_-ber (c_-1); T is te=perature (oK); u is

the optical mass of CO 2 (g c=-2); z Is distance

(c=).

The fllter function. @(v). In equation (2) determines the IR pass band to which

the CO 2 band lay altitude rind shear radiometer

responds. Since the CO 2 portion of the spectrum

is broad, ranging :to= no=lnally 630 to 710 c= -1,

It 18 necessary to choose a passband of a width

of 20 to 30 c= -1. vlthin the broad band which

v112 provlde s sutgsble rmn&e capability. The

absorption (and e=_sslon) across the CO 2 band

varies considerably thus allovin£ s 8reater or

lesser horizontal atmospheric penetration. For

example the CO 20-branch centered near 667 cm -1

would parr.At a ranie of only I fay meters.

WeIghtln B functions are defined by

----_----,s, auue=u 8_A'a kear_ot LabotatOl 7 Is

O.JK. Mence it is |easib|e ¢o determ&ne dotrndraft temperature changes this small at distmnces of 10 In= or mere durlm 8 Blade path

approach_th 8 horizontally ogebiliged radiometer system.

CO 2 - WEIGHTING FUNCTIONS

9S0 rob. 2B? K.A_ - 20era "1

0.4 66? 6.KS900. 9|0 cm-_

/%

,. 0-2 - _ Y --

0.2

0.1

/

-2 -! 0 I 2 3

Io0 z

1 t , , , I

0.1 1.0 10 I00

zlkm)

" F_.gwe _.

f_og'_ona oen_ered a: =7"_ _nd_oa_ed _'req_anc{.ae.

Ca.vbon d'2o=-2de b.or_.zongaZ ue_gF._ir_

din------; " =T e.V / d• (i)

O KEFE/LF.NCES

where I is the atmospheric transmission (dimensionless); 6v Is the wave number interval

( cg-l)_ KAy is the CO 2 absorption coefficient

(c=2g-1); p Is pressure (ego); q is mass _t_in|

ratio of CO 2 (di=enslonlcss); _ is the universal

gas constant (css).

The weighting function describes the ranking

characterlstXcs of the filter, and thus the

range of the radiometer. FiBure 3 illustrates

welshtln g or ranging functions for various

center frequency passbands either 20 cm -1 vide

for CO 2. The position of the peak of the

vei|htLng function defines the "look" dlatancmn

or range of the instrument. Aa an sx-mple

we employed the weighting function of FLa. 3 at

a crater frequency for the CO 2 filter of 685

ca-" (20 cm-I vide). Me assumed a borlsontal

temperature constant at 288K in ass instance

and 2IbK from l.O go 1.6 b distance is _ht other calculation. Th_ CO 2 m_zin| ratio (mass)

van assumed 3.28 Z 10 -u u c_-_ar -&- This

Favbush, E. J. and I. C. Hiller (19S&): A Basis

for Forecasting Peak _|nd &mats in NonFrontal Thunderstorms. Bulletin Amer. Net.

Soc.___. 3__5.I_-19.

Foster, Donald S. (1958): Thunderstorm Gusts

Compared with Computed Do_ndraft Speeds.

_on. _ea. Jev.e 8__66091-9&.

FuJlts, T. T. (1976): Spearhead Echo and Downburst Near the Approach End of A John R.

Kennedy Runway, New York City. SHRF Research Paper, 137, Sl pp.

ORIGINAL PAGE IS

_0_ POOR QUALITY

corresponds to 8 temperature difference of _g.

Infrared Remote Sensing and Radiative Transfer in Wind Shear Detection. P.M. guhn, F.

Caracena, I.G. No]t, J.V. Radostitz. Reprint iron Preprlnt Volume: 3zd Conference on

Atmospheric Radiation June 28-30, 1978.

298
T

1

/

r/

/

1

,.

/i,

'/J7

0

q

M

0 -.I

m

W

i-I

×

It

i,.,,,il'vl

f,lr,l ''l

i.I

Q

Ill

o

',,,4

0

,,.4

ei

to][.z,_rt[ IMION O.L 'TV'NOIB M

299
VALIDATION

FUNCTION

OF _._FRAR_D W_IG_TZNG

IN 1979. RESEARCHER DR. PETER KUHN

AND NASA TEST PILOT MR- GLEN

STINNET FLEW THE NASA LEAR JET #705

OVER THE SANTA BARBARA CHANNEL

ALTERNATING BETWEEN LAND (40 ° C)

AND THE CHANNEL (15 ° C) TO VALIDATE

THE WEIGHTING FUNCTION

THIS VALIDATION INVOLVED USING A

BARNES PRT5 RADIOMETER AND

INTERCHANGING 6 CO 2 FILTERS UNTIL

THE WEIGHTING FUNCTION WAS

VALIDATED

REFERENCE: PERSONAL CORRESPONDENCE DR. PETER KUHN; AUGUST 1987

TURBULENCE pREDICTION BYSTENS

300
J

t

I--

!

Z

:3

I

0

0

0

LO

I

0

0

0

I , I , I

0 0 0

o o o

O O 0

03 _ .-,

.I.HOI IH

I

O

CM

O

_1 "-_

O3

I

O

I

C4J

I

oO

O

U

¢t)

z

{-_,0

r_ {-,

u..l >'. U

_I._O

u.1 (.._ I:_

301
0

II

_E

I--

0

!

Z

I , I I I I I I I I

0 0 0 0 0

0 0 C]) 0 0

0 0 0 C) 0

IHOI,XH

-- ('M

0

('M

-' rO

° 0

-- !

(D

-i< 1

!

O3

-- I

0

I

m

0 I

,B

t--- >...

v'_ t.D

z

Q

.<

t/) ,a:(D

Z ,_cx:

ILl

:> t-_

LI.] •

t:_ >. t.t,

0 u

z

302
THE END PRODUCT OF A I RBORNE Im SENSOR

IS:

A_e (change in radiant -Flux)

A t ( time )

FROM WH I CH WE GET :

A T (temperature)

A t ( t i me )

OR AT

FROM TH I S WE

I NDE X WH I CH

FL I GHT PATH.

W ILL CALCULATE A

APPL I ES TO THE A I

HAZARD

RCRAFT" S

TURBULENCE BRED I CT I ON SYSTEMS

303
m

W

V)

I-.

wO

a I.-.

304
F FACTOR

/

WE NEED

A I RCRAFT

VERT I CAL

TO ASSESS THE THREAT TO

I N BOTH THE HOR I ZONTAL

W I ND COMPONENTS .

THE

AND

--HOR I ZONTAL CASE

THERE I S A GOOD EMP I R I CAL

RELAT I ONSH I P BETWEEN TEMPERATURE

DROP AND NOR I Z ONTAL W I ND VELOC I TY .

TURBULENCE PRED I CT I ON SYSTEMS

305
_o

Z

0

0

o_

_o

[_

O_

,,.4

+

0

(_rl _Ii]o¢_) s.toN_i 0

306
D

C_<

_o

O_=o

UD

C_>

OQ

C_Z

o

&,3

--4I0I

Q

z-.

om

I [.-, _1 II

307
12

4

2

0

I0 15

UMRX [M/S}

REFERENCE: • F. PROCTOR/R. BOWLES, NASA LANGLEY RESEARCH CENTER

308
FROM THE NASA TASS

RELATIONSHIP IS:

MODEL THE

m

A

_Umls = 2 .

SO TO GET HORIZONTAL

FACTOR

WE GET :

= --AT 2.5

g

PORTION

T

G

OF F

I N DE(3

IN m/s

C

WHICH THEN

EOU I VALENT

IS THE

OF."

TEI_PERATURE

Fw = WX

g

REFERENCE: "THE TERMINAL AREA SIMULATION SYSTEM"; BY

PROCTOR; REPORT NO. DOT/FAA/PM-86/50, I NASA CR-4046,

I: THEORETICAL FORMULATION;'APRIL 1987.

FRED

VOLUME

TURBULENCE PRED I CT I ON SYSTEMS

' 309
--VERTICAL PORTION OF F FACTOR

NEOAT IVE BUOYANCY HAS LONG BEEN

RECOGNIZED AS THE MAJOR FORCING

FACTOR IN DOWNBURSTS .

%

THE BUOYANT FORCE IS=

AT °

T e-v-1

WHEN AT = T -- T.,_

Tm

TEMPERATURE OF AIR PARCEL

AMBIENT TEMPERATURE

TURBULENCE PREDICTION SYSTEMS

310
FOSTER" S WORK ALLOWS

THE VERT I CAL VELOC I TY

TEMPERATURE DROP

US TO

FROM

CALCULATE

THE

r

o

w /

_o

dW = g ,,_../_T °

T m

7_.. S

0

( i--z/Z ) d_-

WH I CH

W --_

REDUCES TO

g Z _]_-" /_T °

T m

AND

W -

SEE PLOT OF

TEMPERATURE

W I NDS

FOSTER VS 2 9 1

DF_OP RELATED TO VERT I CAL

REFERENCE: "THUNDERSTORM GUSTS COMPARED WITH COMPUTED

DOWNDRAFT SPEEDS"; BY DONALD FOSTER; MONTHLY WEATHER REVIEW,

MARCH 1958, PP. 91-94.

REFERENCE: "A SHORT COURSE IN CLOUD PHYSICS"; BY R.R.

ROGERS; 2ND EDITION; INTERNATIONAL SERIES IN NATURAL

PHILOSOPHY VOLUME 96; 1979.

TURBULENCE PRED I CT I ON SYSTEMS

311
0

[.q

E-_ <

OQ

[.q

b_

09Z

I----I

0 CO ¢D ql4 t'_

0

312
oJ

0

Figure 8

313
WE CAN THEN ASSUME SOME Z (ALT ITUDE )

AND

Fv "-

--g _ Z_ ATA IRS PEED

WHICH IS THE TEMPERATURE EQUIVALENT OF

Fv --

Vw

As

SO COMB INED HAZARD

OF TEMPERATURE IS :

FACTOR AS A FUNCT ION

_ --g_Z _/_T- I

2.5 _ --/_T Tm

g A IRSPEED

TURBULENCE PREDICT ION SYSTEMS

314
CONCLUS _IONS :

NOW WE HAVE COVERED BOTH ASPECTS OF

CONCERN TO THE A IRCRAFT FROM THE

HOR IZONTAL WIND RATE OF CHANGE AS

FUNCT ION OF EMPIRICAL AND MODELLED

WORK RELATED TO TEMPERATURE DROP.

VERT ICAL WIND VELOC ITY

ACCEPTED FORC ING FACTOR

TEMPERATURE DROP

FROM A WELL

RELATED TO

TH IS CALCULATED

RELEVANCE TO THE

PRESENTLY IN USE

HAZARD INDEX HAS

IN S ITU SYSTEMS

TURBULENCE PREDICT ION SYSTEMS

315
t_

i--

>-

°..

l'-Z

316

m
WHERE TO NOW :

TI-IEORET I CAL WORK I N PROGRESS

--NU I SANCE

--COLD

--GUST

ALARMS

FRONTS

FRONTS

--SPEC I AL CASES

SNOW DR 2 VEN

STABLE LAYER

DEF I N I T I ON OF STANDARD

TEMPERATURE NO I SE F I ELD

WITH

PROBAB I L I TY OF NU I SANCE

FOR I NFRARED SYSTEM

ALARMS

PROBAB I L I TY OF NU I SANCE ALARMS

FOR AN INTEGRATED SYSTEM

TURBULENCE PRED I CTION SYSTEMS

317
OPERAT I ONAL ENV I RONMENT

WE HAVE OBTAINED WIDE--SCALE USER

INTEREST TO ASSIST US IN EVALUATING

OUR SYSTEM

4

WE ARE

FUNDED

SYSTEM

PROCEED I NG W I TH A PR I VATELY

I N--SERV I CE EVALUAT I ON OF OUR

( 1 2 MONTH PROGRAM )

QUEST I ONS WE WANT TO ANSWER

W I LL OUR

REL I ABLE

RESEARCH

OPERAT I ONAL

AND ACCURATE

I NSTRUMENTS

SYSTEM

AS THE

DID?

PROVE AS

IF NO:

REEVALUATE

CAND I DATE

INFRARED AS i V I ABLE

I F YES =

THE NAT I ON

SAFETY NOW

W I EL HAVE I NCREASED AIR

TURBULENCE PRED I CT I ON SYSTEMS

318
TPS I N--SERV I CE EVALUAT I ON

GOALS =

PROVE TPS" S ADVANCE

SYSTEM PERFORMS WELL

OPERAT I ONAL SETT I NG

WARN I NG

IN AN

HELP ESTABL I SH INDUSTRY

EVALUAT I ON CR I TER I A

ASS I ST I N OBTA I N I NG

CERT I F I CAT I ON

FAA

:S

TURBULENCE PRED I CT I ON SYSTEMS

319
TPS" S FUTURE

GOAL = FAA CERT I F I ED SYSTEM ( 1 988 )

METHOD -- I N--SERV I CE EVALUAT I ON

INDUSTRY PARTNERS

PIEDMONT AIRLINES -- 4 SYSTEMS

1988

HONEYWELL/SPERRY CORPORATION

T I METABLE FOR

EVALUAT IONS

ALL I N--SERV ICE

1988

E X PECTED A I R T I ME

12 SYSTEMS -- 24 , 000 FL I GHT HRS

_K

W<

ANALYS I S

TPS ( HONE

LEARN )

I NDUSTRY

FAA

OF I N--SERV I CE DATA

ALGOR I THMS AS WE

PARTNERS

TURBULENCE PRED I CT I ON SYSTEMS

320
QUESTIONS AND ANSWERS

J,

JIM EVANS (MIT Lincoln Labs) - Your program sounds like a

good way to start trying to address some of the false alarms.

the other hand, one hopes they don't penetrate microburst very

often. How are you working at trying to establish what the

detection probability is for this combined system?

On

PAT ADAMSON (TPS) - One of the things we are going to

do--and that was part of my last slide--Since the hazard index is

applicable to both systems assuming that everybody did their math

correctly, we will time tag the data. Part of our data gathering

technique will be to look for shears or hazard index such that

they may not be terribly hazardous to the aircraft. And it will

look for a similar event to occur at some time after that in the

reactive system. That is what we are hoping to do. If we get

shears over the year that is bad or good, I don't know which.

JIM EVANS (MIT Lincoln Labs) - Again, I understand how you

can do that comparison, what I meant was how will you? This

plane could fly all summer and never see a microburst. How will

you establish whether it detects microbursts or not, in this

situation? Wouldn't you really have to have the same system and

get a plane out and try to fly it around and try to fly it

through microburst?

PAT ADAMSON (TPS) - Well, I don't think so. I mean, I think

that bas already been proven. I think for example, the report I

just showed from Quinn and Sinclair was a completely equipped

plane that the B57B was a completely equipped plane--I think they

worked properly, it showed they worked in the optimum research

section. I don't think we are every going to get proof that they

work in the operational setting--nobody is going to take that

chance.

321
z

0

u

U

uJ

h"

_Ll

_3

<

US

"r

_3

Z

U

0

z

U

0

0

..J

<

n,

0

IJ.

Z

z)

0

0

U

<

m

:E

uJ

u_ :E

>. us

m

--

Z LU n_

0 U m

Z a.

< < xtU

_3 -J n_

w ,7, o

•_ n_ z

0 _ tn

tu

F- .J _-

z _ u.

z a. n_

0 --

"J 0

i

F- _" m

w LU 0

Z -J

m

FU

m

0

Fz

tu

U

z

0

m

U

t_ LU

t_

It. >- <

Z .J ILl

-- n_ _.

m ,_ tn

m

m 0 z

_. z

u. 0 _u

0 _- _

>- .j -

_- 0 F-

.j t_ -J

- <

m tn

- _ _

.J

ul ffl

u. >. _

N88[ 7629

_ "_ 0

< he

< -- 0 |

|

oRECED|NGpAGEBLANKNOT FILI_E'D,

/

323
-r'_ U

,,¢0

nL

nL

.¢

I-Z

I,LI

Ul

I,n

i11

gl

¢/I

.¢

)-

I--

eeme

_1umm

Ul <

ILl

III j,|

324
325
il

_

_o<_ ....

<n,

n, o

u_

_z

--ILl

_ _ _

_ 0 u. ._ < --

o__

W • • • • •

_'0

n, 7

u.u_

7u_

T

o _z= ,,<

o_

_z_

i

I

!

|

i

326
/r ORIGINAL PAGE I$

OF POOR QUALITY_

• @

327
w

z _

z

o

_____8_ o_<_

_ z

_8__<_

_m...m.....m.m _..m.

!

II

ril

328
00n

II/1W

h- iW

329
i/1

Z

0

_1

U

Z

0

IJ

Z

I-

-I

1,I,I

>.

<

zi

..I

ILl

1,1,1

_ :_ _ _ _,,

: 7

_.- _ _ _ _" _ ='

_a

I,t,I

O_ _ 0

_ _ _ _ooo _ _ _

_._ ,, _

330
33NWIlIWSNWWI

ORIGINAL PAG_ l_. .PO0, ,-,, r_

" " "" '_uALITy

33NUI11WSNUWI

E

i

B

331 " 'J
LUr

I-- A

ELI m0zVZ0!

I--<

I-- U

,-I

ELWZ<m<

_1<m

o0

m

o

oo

D

0o

0!

u_

0

II)Nm

r_| 0

/!*- 1"3

C,

0_

cO| _

m

/.

4,•

0m

¢Y•

_°

e-_ ip + •

"it

pc) B I I ! o I_ 0

(Sll_llll:) ]311VlOYil

"/'"

!

ooo

V

i,,,,,,

00 t0 0 I

c/)

El

1

'_' 332/
ORIGINAL PAGE IS

OF. POOR QUALITy_

Z

m

<

LIJ

2:

-r-

£

I

N

<

>

Ld

.(

E

uJ

Q.

£

U3

U

E

LIJ

£

o

ml

<

\

\\ // I

ii_/"°

\

\

t) LL

_ _ ,

--: |_

._J

ILl

Ill

14"

UJ

o

0

m

! • !

I_ 0

(J lil9) :lilfllttl]dkl]l

o

o

o }

¢_ ¢D

Z

O

8D

O

C_

p

o

!!o

O

U)

E

4-)

U)

$

" 333 ..... "
. i I e o

x f rrrr f(k_.

\

0

\

N

ORIGINAL PAGE I_

OE POOR QUALITY

!

334
nILl

t,/'; aZ

u-OI 0 z Z

O0 •-- 1.1.1

I--

(5>..

I

i-tr

>0

_tO

ILl

n-n- O

I--

,,,,.I

I

Z0

I-Zm

'1- ai

335

0

n"

,.,I

II Z

r,..

nI,LI

In0

ItO0

N88- 17630

uJ oz

iJJ

ct) IJ_0

rr

t.lJ

I.-

00

ILl

"1-

In"

o_

Qn"

WW

it

_z

wO

---_: v

rr"

OuJ

mO

U-W

O-1- z _.-

I----

Ouj

h-u,l w

iJ.l wI

uJ

nI--
m

I-- U

ILl

0o0

(z)

uJ

,,<, z

n

rrZ

0.w

u.n.

Ow

mr7

w_

13.

m

wCC

wr7 0I

"_CC

o_z

_o

rT0_

Zu_

o00I Z0

,<

_J

c/) da

w"

._J

,<

uJ

rr

o" W

I-- 0

_.I

13. Z

o') ww<

n-

(z) w0Z

,<

r_w

,<aZ0W

_J>w@

336
Z

0

m

lJ

N

0

1-

O0

_-o w

u_rr n-c/) uJ

i__7"

Z(D

D_ W --0. _,5 O0 oO _o, w on"

Z 7-

7- rr,,__ _ w I- rr

o_ 7-.. _.

n- >- '_

o_

',_00

o d o:_ ,7,-r -r---z 0 ccwo0 _ 3_ww

=_ 8 o0:=_ _ ,,z_ ,,z_- b_<

(Dw _ oOWW _ uj ::> ',_

Z _ wZ_ n-" n"- _ :30 < _ _<

=_ _ _ooo wWWU_ u_ _-_ _z__<< 13: > , , ,

0 _ m_u. ,, o< ,,,

o0 (D o< w

o.. w Z

o _ _ z< _, _-<_ o 00 ,u".Z

nm I--" -r u.I

_- U..I -L j Z

00 _, _,oo__ _ "'=_o_ ,,_ Z

#. _ c_ooo 0 0 0_

Z (.9 09 D O3 O0

0 "7 0 (,5 w w

0. L_ O. _ CO ,_l

! I I I I I

337
.J

uJ

1:3 0

=E

rl-

<{

uJ

-r

{/)

:=

I

T ..... °

\

L4_ o

E)

c)

II L I

L4_

<3

C3

I

:4

d

338
ILl mO

LU

ln*

I--

LIJ 0Zm

LIJ

LIJ

"r

I--

_I,DI

(,ClJ

J'='i

t.=ml

[431

1201

I00

ORIGINAL PAGE I$

O_ POOR QUALITY,

..,1 0z

z

,c 0,

uJ

l/

00

01

00

61

00

0

_0

_0

0

0

g)

"0

c- O00

or) W

(_eaj) =JCIN1117V

33g
Z0m

:!

uWm

I

..I W

nUJZ

LU0

O0

_J<>

UJ

C]

O00z00

ulao

r_

rn!

Y0W

F-I

_J

u_

_J<Z0Z

LU>Z00I

Z0

"I- 0<

rn0

rr

LLZ0

Q.0

LU0Z<D

(.5

UJ

uJ

rr

-r@

uJ0Z

uJ

.J

rn

rrX

kwet

-_0

rn>

_ HI

z_

>-Z

-r

coon

o3

am< ©

LU-1-

<m

D<<

zwm

-- -r "-r !

u_

i1©

u.l <

b- <OZ

(5ZO

..J

_.1 O

la_

b-

__1 <

k- w

U.l <

L_

_..

LIJ

l--- Z©0Z

I_LI <W

O0!

<

UJ0Z<

r_

(.5

r_Z<

rr

uJJ

uJ<

LU

UJ

O0

O0<

(5ZZ

LU

O0

iii

Orr

W<

u_ u.I

_"r"

wc0

a.

I

340
341
SHEAR MODEL B

_IND

40.

0

HORIZONTAL WIND

(KNOTS)

-40.

VERTICAL WIND

(FT/SEC)

1 I i t t

I ! t ! i

i i I I !

I I I i

"_ g i I !

_t ! ! I

i\t I '

/i

i i , ! i

40110. 8O00.

i i t i i

I

• i-A

: I /_ I

: IV! _ i

40 bO. 80110.

t

I

I

I

I

I

I

/

/j

t

I

i

I

I

I

i

i

l

J

i

/i

i

!

|0.

CROSSWIND

(KNOTS) 0

LEFT

T

l

'.

40_ IO. 8000.

-i i

00. l

t

GROUND DISTANCE (FEET)

342

ORIGINAL PAGE IS

Q_ POOR QUALITY
X

i

n1--

111

m

I-

.=I

ILl

rr

O9

I--

0

.--I

Q.

Or)

W

LU

I.--

<

rr

I---

O9

LU

0

Z

<

a

0

!

LU W

nC_

c--c_. 2 J .--Im

<<Igg2

_ 0

Da<

ww_

ww_

ZZ_

wwZ

_ww<

ZIIW

<00_

__0

wmw

_www

!

k0

_J

n

n_

W

13.

_l

_I

LU

0

7-

0

<

III

Z

Or)

7

0

EE--

III

EL

UJ

rr

.J

_J

iii

0

O4

I

oO

<

rr

<

w

-IoO

_6

Z

ZD

rr

cO

>-

rr

LU

LU

C_

W

Z

<

7-

zW

On*

n>

0>-

._I

w_

I

343
I 0

<(8

_Z

O0

IZ

0

LU

_-0

_Zz

o

"'0

i0

t I i 00 0

0

0

0 ! 0 I 0 0 0

0 I 0 I I 0 I 0 I I 0

t0 I 0 I I 0 00 III

I,c

tIIIIII ,c IIII

I"-

I

0 ,c I

I-0--I _, III ,.- II

I'(

III n. III ,,, III ,C II

a, Il ^

0 i_ZH

0

00000CA

Iii

344
N

Z

0

m

!-

0

uJ

0

Z

<(

a

3

z

0

mllll

p.

<

E

iil

..J

u.I

0

0

<

!1

0

LU

.-I

a.

X

LU

0

0

nuJ

-r-

(/)

L.

0

.E

E

Iii

[]

0

0

0

v

iii

_J

Z

<

r'_

(feel)EI(]AIII]V

347

PRECF.DING PAGE BLANK NOT Fl_r._

J
iil 0Z

<C

ml 30

iil

_J0Z

,<

-r"o

I--o

<( ,-

a. <{

I- rr

-r ,4: w mira

..j 3::

U. (/)

U. 0W

.J

I1.

:E

<{ XW

t_

E)

(I)

.E

(._E

I,I

[]

O•

u') 0

I,,,,I ,,,, I,,,,I ,,,, I,,,,I ,,,,-

0

a)

V

LU

rJZ

CO

(;eej) :ION±I±-IV

348
h

:.6

COMPARISON OF ALTITUDE PLOTS IN TWO RUNS

WITH SHEAR Al10 AND FLIGHT PATH ANGLE GUIDANCE

p

j===_

v

LU

C_

IF-

._1

<

600

500 --

400 --

300 --

200 --

100 --

0

0

RUN A

RUN B

%

%

I I I

5000 10000 15000

DISTANCE (feet)

349
COMPARISON OF PITCH ATTITUDE IN TWO RUNS

WITH SHEAR Al10 AND FLIGHT PATH ANGLE GUIDANCE

(b

"0

v

LLJ

D

I--

I--

i'-

,<

"I-

(D

I'-

CL

26

20

10--

0 --

0

RUN A

RUN B

\

\

, I I I I I

10000

I I

15000

DISTANCE (feet)

350
COMPARISON OF AIRSPEED IN TWO RUNS WITH

SHEAR Al10 AND FLIGHT PATH ANGLE GUIDANCE

7

#,

:v

u)

O

t-"

£3

LU

LU

EL

n"

<

200

150

100

m

b

50

0

RUN A

RUN B

5000 10000 15000

DISTANCE (feet)

351
I,LI

"r"

I,U0

IX

I-- Zi0

I-"

tL

LUZ

-r0z

_.1

t---

rrI

I---

121 W

k- 0

if)

Or) W

..Jm0

rr

...1 0

nI-- Z0 I

Z

121

5

a_

zo_

w0

_:£_u_ z_N

IIIII

352
ID

I.U

'l-

"r"

0

I:1:

'1'-

I,-

I,,,-

'lm

..,I

IJ.

I,L

0

LI.I

J

X

i,i

w

C_

In

I-

--I

x

0

i

u

w

I,,,,I,l,,lll, II,,lll,,,,I,j,,-

-_ V'l

1"3

o

o

W,,,-

V

uJ

0

Z

FOg

a

(_,eej) 30rlllllV

353
IZ

ILl

-r

O_

"I=

0

0

tr

-r

h-

-I=

0

m

.d

0

W

.3

a.

X

uJ

m

m

u

o

_t

i

I I I I I I I I

A

Q)

V

111

0

Z

I--

O_

a

O

(u!wrlee;)aNIM 7VOIIEI3A

8,54
a,

I:Z:

,,d:

ILl

'T"

I'-'

LLI

--I

0,.

,,d:

x

ILl

E,

x

0

-- c',,I

o'1

N

__00

ar=,-

m

_ I",..

i

Z.O

ILl

m

r'l

m

,'-"

•- W

__o Z

<

- I-

-- O) 0")

- a

ml,,,

--tO

--14'_

m

-- P'I

z',,I

I,l,l,l,l,l,l,i,l,l,l,l,l,l,l,l,I,-

q" t'_ 0 _0 _ _ _ 0 _ ¢D _" ¢_4 0 ('_ _" _ 00 0

_1 C_I _ _ _ _ _ I I I I ',,r'-

I

o

(Bep) ::lonllllV HOlld

355
I,,- tJ,.

0

I-

"1- LU

Z

I.I.

0

ILl

--I

a.

x

ILl

i

i

h

i

I

I

I

iq

I

x

0

VI

T"

1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1'

_ N ,r" _'- e- v- v- l I I I T

q

I

I

mr,.

I

I

a

m

I

I

O

v

I.LI

0

z

<l:

I--

09

D

(Bep) >lOVlJ.V :lO BIIDNV

w

356
I'"

I,.L,I

-l-

-r- 0

"rl-'-

I-,,

-tin

.-I

I,.A,,.

14. 0

LAJ

..I

a. X

L,U

0

rr,

L,U

"t- O

I,- m

0..

A

(3)

¢)

LU

¢.) Z

l--

C/)

£:)

(6ep) 1:101:t1:13HO/Id

357
Z

i,l 00

I-0

--I n

rr

uJI

09

c_Z

rr

LUZ

LUZ

LUT

-r0

h- n

LIJ 0a

UJ

rr0

h- Z0

_J

LU

rr

>-iZ!

E

z

S_m

@_5zoE

II!I

358
4

Z

0

m

,,,,.I

Z

0

0

ILl

_J

r,..0

Z

-r

"1-

(.5

..J

LL

O0

LU

0

Z

a

_5

(5

Z

O0

0

nr

o.

¢0

0

@

o

o

r--_ b <, o ,.I<

2 2 _ o "H,

,C-w=o 7o

Z_

o_ -_. <_" w_- O0w " ON

_.g ow wo°

so _< W_ ow eW zrn '"e g_:

_- c-o 5 ° _"w w _-.0

I I I I I

359
SIMULATOR INVESTIGATION OF WIND SHEAR RECOVERY TECHNIQUES

An effort was conducted to develop techniques for flying "near

optimal" tra]ectorles, during inadvertent mlcroburat encounters,

when the microburst flow field ahead of the airplane la not

known. Only the takeoff wind shear encounter case was considered.

The research was done in two phases. In the first phase, a batch

simulation, conslatlng of a simple point-mass performance model

of e transport category airplane, was used to develop candidate

wlnd shear escape strategies. A simple analytical wand shear

model was used In the development. In the second phase, the

strategies were evaluated an a real-time, piloted simulation.

Both the simple analytlcal wlnd shear model and a second model,

baaed on the vortex clrculatlon encountered in the Dallas-Fort

Worth accident, were used in the piloted simulation. The three

guidance options tested were: pitch attitude hold, which

commanded a constant recovery pitch: acceleration, which

decelerated the airplane am a function of the instantaneous shear

strength: and flight path angle, which produced a minimum

altitude tra3ectory. All guidance options were presented to the

pilot on an electromechen£cel flight director for manual

tracking.

The results showed that the moat promlalng guidance option ia the

£11ght path angle guidance, but that the experimental variation

in recovery performance between runs wee greater than the

dlf£erences between guldence optlona. The distribution of

airspeed lose across e wind shear was important. In a severe

sheer, a steady reduction in airspeed was less efficient than

Initlelly conserving kinetic energy, end trading it off near the

end of the shear. The vortex circulation shear introduced

additional factors into the recovery. There is evidence that the

optimal recovery strategy may be slightly different in the vortex

encounter than in a classic downburat model. The maximum

horizontal wind change capability of the airplane was much leas

in the vortex shear model than in the simple analytical model.

The pilots were initially reluctant to reduce pitch attitude

close to the ground, upon entering the shear, but later observed

and commented on the benefits of an initial pitch reduction.

ORIGINAL PAGE IS

OF POOR QUALITi_

360
QUESTIONS AND ANSWERS

KIOUMARS NAJMABADI (BOEING) - Earlier you showed the

altitude profile of the three strategies when subjected to your

analytical wind model where the horizontal wind is the same for

all the strategies. But, any strategy which tries to climb will

be penalized because your vertical wind is a function of

altitude. Now did you compare, or do you have the same

comparison for your B model?

DAVE HINTON (NASA LaRC) - Not directly. The reason is the B

model is not implemented in the batch simulation. You're

refering to this first chart, this one?

KIOUMARS NAJMABADI (BOEING) - That is right.

DAVE HINTON (NASA LaRC) - Okay. That particular simulation

batch model does not have the vortex shear in there. The reason

is, it is a very simple point airplane model and I can't hope to

really duplicate all the effects. That is, the stability effects

and control problems associated with shear B. Therefore, I didn't

put that one in.

KIOUMARS NAJMABADI (BOEING) - The fact is that if you climb

higher--I agree with you that the intensity of the down draft and

all will increase--but at the same time I think that also the

shear in the horizontal will decrease. If you look at the

existing model.

DAVE HINTON (NASA LaRC) - I did run these same cases with no

vertical wind present. The effect was not as large. But I saw

that it was bad to climb there also. It was not just the effect

of having the vertical wind stronger at altitude. Just giving up

the airspeed is also bad.

PAUL CAMUS (Airbus Industrie) - I have two comments related

to one of your viewgraphs. The comparison of altitude plots in

two runs with flight path angle guidance, I notice that there is

a large experimental variation in performance recovery between

two runs with the same guidance. If you consider run A, a large

pitch change demand is required to stop the altitude loss. And

it seems to me that in the case of run B the pilot did not

respond to the flight director commands.

DAVE HINTON (NASA LaRC) - He did not respond as quickly or

as aggressively?

PAUL CAMUS (Airbus Industrie) - Yes.

DAVE HINTON (NASA LaRC) - That is correct. The pilots all

temper the flight director somewhat with what they expect to do.

And if there is a very large say--from 16 degrees to i0 degree

pitch change--pilots may follow it very aggressively or not so

361
aggressively.

PAUL CAMUS (Airbus Industrie) - Which means that it might be

a problem of training, and the constant pitch might be the best

anyhow.

DAVE HINTON (NASA LaRC) - There are a lot of issues that I

didn't have time to get into. A lot of training issues were

raised during the simulation study.

PAUL CAMUS (Airbus Industrie) - I have a second point. It

seems that you accept a large flight path declination before you

accept the deceleration of the plane. Therefore, during the

initial phase you have to pitch down to track the air speed--Also

a down draft at this moment.

DAVE HINTON (NASA LaRC) - In shear B that is precisely what

happened. In shear B you'll notice we are climbing and then we

change that over to a descent. At that same time the airplane

has been hit with the first down draft, which was the strongest

one, and because the down draft is helping the pilot to

accomplish his objectives (in arresting the rate of climb) it

wasn't even really noticed. The last down draft, which was not

quite as strong, is usually the one that really hurt the

aircraft.

PAUL CAMUS (Airbus Industrie) - Do you believe that a pilot

would be prepared to accept a negative vertical speed in the

initial phase when he has high kenetic energy?

DAVE HINTON (NASA LaRC) - Our pilots did seem to believe

that it was acceptable to have smart guidance decending them

towards the ground. The rate of decent in each of these cases

was limited to about the same value you would see in the glide

slope, about 600 feet per minute, so it was a very gentle

decent. Again, it goes back to training, because initially the

pilots did not like it. After flying about 30, 40 50 runs they

began to see the advantages of doing that, and were more

aggressive in pitching over. Obviously, you can not have every

airline crew flying a hundred runs. So there is a definite

training issue.

PAUL CAMUS (Airbus Industrie) - Thank you.

DICK BRAY (NASA Ames) - Dave, I want to sort of put this to

you as a question. On your flight path control law going into

shear B, the perfect following of that shear law would still

require very rapid pitch of the aircraft at about that 6 second

period wouldn't it?--Just to maintain? In other words that was a

very demanding, very active pitch task produced by that law.

DAVE HINTON (NASA LaRC) - The pilots varied. They tried

362
various gains, of course. Three pilots used for our research

were test pilots here at NASA, not line pilots. They varied

their gains and I did not see anything beyond the realm of what

you could do in an operational environment. They did not feel it

was beyond the realm. The guidance was presented to them in the

form of--if I wanted them to go to i0 degrees of pitch--that is

where I put the needle on the flight director. It is entirely up

to the pilot to close the loop and get the airplane to that pitch

attitude.

DICK BRAY (NASA Ames) - Okay. But just flying through that

would, if he followed it perfectly, be a very, very active

pitch.

DAVE HINTON (NASA LaRC) - Actually, the needle movement was

limited to three degrees per second, so that is not beyond the

realm. That was the limit on the pitch needle movement rate.

DICK BRAY (NASA Ames) - You wave a sort of nasty dynamic

problem with that particular shear. I was wondering whether you

ever considered flying to an air mass flight path instead of an

inertial flight path.

DAVE HINTON (NASA LaRC) - We could do it either way, it

would be a similar task.

DICK BRAY (NASA Ames) - Yeah, well there should be an awful

lot less activity if you were deriving flight path, with angle of

attack with the proper amount of lag on it. It should really

stabilize the pitch command. You'll get an oscillation in the

flight path but (paused)

RALPH COKELEY (Lockheed) - Dave, I've got some concerns, and

I don't question the validity of what you have shown us, but I

want to point out to the rest of us that have not been in the

piloting picture (and perhaps associated with some of the other

studies), that at this moment we don't have a means of

recognizing the shear instantaneously. And, for the next four

years we are going to be doing it differently and training some

25000 pilots to do Jt differently. Up to that time our accident

picture has been letting the nose drop too far and too late. So,

the emphasis for the next four years is going to be not to let

that happen inadvertently when you don't recognize it. So even

assuming that this is valid, we've got some road-crossing, down

the road, to change paths and change guidance strategies to make

something like this work.

DAVE HINTON (NASA Ames) - That is true. That is very true.

363
iB

N88- 176 __i

:ii!iiiii!ii;_i_----_-- _:_,......

::::::::::':"::::: " : :.::. : ': i:.

_!!_!i_"!_!::_:: _: ...::::: .:." "- ' ....

:!i!i!iii!i:i:i-i-:.:i:i:-:-:_ :_:::.:._.:....

.-.!:i:_:': .................. 365
Slide 1

Crew Interface with Windshear Systems

Dave Carbaugh is one of the investigators involved with Boeing

Commercial Airplane Company's contract with NASA to conduct

windshear studies. The Flight Deck Research Group is primarily a

human factors group focusing on advanced commercial transport

projects. Dave Carbaugh has a degree from the United States Air

Force Academy in engineering mechanics and a masters in aviation

management with a human factors emphasis from Arizona State

University. In addition, he has over 5000 hours jet time and

2000 hours instructor time in various aircraft from the F-15 to

4-engine heavy jets.

366
O3

(D

u)

O3

IliUm

qD

¢,.)

O

o3

k_C00<

00<Z

0

c- O0

cC_

LL

B

cCD0CZ

CE00

CD

or)

c- O

rr'

0

367
Slide 2

Crew Interface with Windshear Systems

The topics to be presented at the First Combined Manufacturers'

and Technology Airborne Wind Shear Review Meeting include:

i. A review is given of the areas within Boeing that are

presently working on the NASA contract to conduct windshear

studies.

2. A synopsis is given of the work in particular that Boeing

Flight Deck Research is conducting•

3. A short review of nuisance and alerts is given in light of

upcoming forward-look technology.

4. Finally, an explanation is given of the research issues

document that was distributed to the meeting attendants•

t

368
m

369
Slide 3

NASA/FAA Airborne Windshear Program Elements

Boeing is working in three areas on the present NASA windshear

contract. These areas include hazard characterization, sensor

technology, and flight management systems. These areas mirror

areas of the NASA/FAA Airborne windshear program. In the area of

hazard characterization, Boeing is studying windshear physics

modeling and improvements to windshear models presently used.

Future work will look at heavy rain aerodynamics and the impact

of microbursts on flight characteristics. In another area,

Boeing will assist NASA in the evaluation of windshear advanced

technology to include forward-look sensors and sensor fusion.

The last area is in flight management systems which is handle by

the Flight Deck Research group. We will look at system

performance requirements, guidance and display concepts, and

pilot factors and procedures.

370
A SLIDE WAS NOT AVAILABLE TO

ACCOMPANY THE TEXT

6

b

371
Slide 4

Goal

The long term goal of the Flight Deck Research groups' effort is

to provide industry with a data base of crew information

requirements, crew performance requirements, and display design

guidelines for use in development and manufacturing of

certifiable airborne windshear systems.

372
o.

,ml

.p

m

0

E

373
Slide 5

Objectives

The way we are going to meet this goal is to accomplish these

objectives:

i. We will establish the information requirements needed by

flightcrews in order to avoid hazardous windshear conditions.

2. We will develop candidate formats of how the information

needed by the crews will be displayed on flight deck.

3. We will develop operational and functional requirements for

integration of reactive and forward-looking windshear sensor

information as received by the flightcrew.

4. We will develop the procedures and criteria necessary to

demonstrate that flightcrews are performing correctly to the

windshear information displayed to them.

5. We will evaluate candidate crew interface requirements to

determine recommended guidelines.

374
¢0 CO

375
Slide 6

Crew Interface with Windshear Systems Program Approach

The crew interface with windshear systems program approach will

be to take all four areas of interest( crew information

requirements, crew performance requirements, operational and

functional requirements, and control and display requirements)

and develop candidate crew interfaces and displays. These

candidates will then be evaluated in the laboratory, simulator,

and in aircraft. The results of these evaluations will be used

to recommend design guidelines for advanced windshear detection

systems.

376
o

,p

m

377
Slide 7

Tasking of Present Contract - May 1988

This slide represents the tasking of Boeing Flight Deck Research

efforts to complete the present NASA contract. The highlights of

this tasking are the program plan, establishment of preliminary

information requirements, and categorization of windshear alerts.

378
00

00

(3)

or)

C(1)

,--- • •

£

c_

379
Slide 8

Establish Preliminary Crew Information Requirements

This slide represents how our group intends to determine the crew

information requirements. The use of a survey of crew

information issues will help determine critical areas of

understanding and required research. A literature review will be

conducted and the requirements for additional data will be

understood. The survey, literature review, and requirements for

additional data will help establish a windshear data base from

which a first cut of crew information requirements can be made.

Display development can begin once this first cut of information

requirements is performed. The crew information requirements

will be refined by crew performance testing, sensor development,

display development, operational changes, and technological

advances.

4

6

380
llii iii Giii

iiiiiiiiiiii_iiii_ _iiiiiiiiiiiiiiiiiiiiiiiii

Liiiii!iiiiiiii_iii!iii _iiii_iliiii_!!iill

:_:_:_:_:_:_::_:_:i F_:_:_'_:_:_ tiiiiii_iiiiiiil_i!iiiiiiiii;i!iiiiiiiiill

I_z_z_i_i_ii_l _iii_i_ii_iiiiii_iiiiii!iii!iiiiii _

ii!iiiiiiiiii_ iii_i_i_i!_iii iiiiiii!iiiiiiiiii_ii_ii_i_i

iii!iiiiii!iiiii!ili_iii_i_ili_i!i_i!iiiiiiiiii!iiilJ!i

_iiii_i_!_!ii_i_iiiii!_!_i_iii@iiii_i_i_i_iiiii_!_iiii!i_i_iiii_!ii_ii

ili<iiiiii_.i_iii_!i_i_i!!iiii!ii!ii!iiiiiiiil _i_iii_!_ii!_i_!_!_i_i_i;i_i_i_i_i_i_i_i_i_i_i_i_i_i_i_iiiii_]i ii_:iiii!i iiiii!!i!i!iiiii ]ili!iiJ!i !i!i!iiy!i!i

f

0

381
Slide 9

Categories of Windshear Alerts

This slide represents our groups method for determining the

categorization of windshear alerts. Alert categories for all

windshear stages will be determined by understanding crew

information and alerting requirements, the time available for the

pilot to respond, and crew operational procedures. Once alert

categories are established then we will use the established

standards for crew alerting and determine the established

presentation philosophy for each of the windshear alerts. For

example, if a windshear were detected at a range of 5 minutes

then perhaps an alert category of advisory would be established.

The established standards for crew alerting would then be used

and the display would probably just be in a message form in the

malfunction/message display area.

4

382
Q

W

"0

mJ

0

u_

0

\ ___ I

383
Slide I0

First-Year Program Schedule

This slide represents the timing of the events required to

complete the first year of Flight Deck Research groups' present

windshear contract with NASA. Highlights of this schedule

include the preliminary information requirements in January of

1988 and the alert categorization in February of 1988.

t

384
<

0'

4

LL

c_

z

<

r_ N UJ _ UJ Or) n_ W 0"_ r_" _7

385
Slide ii

A Look at Alerting

It is very important to look at alerting and nuisance when

considering forward-look technology windshear systems. These

systems must be design with the special requirements of the crew,

the decision making force, in mind. These systems may be

executive or advisory in nature. Advisory systems are those

systems that provide the crew with guidance which they follow

only when, in the crew's judgment, they have some other reason to

believe that they should carry out the indicated action.

Executive systems are those systems that provide the crew with

guidance that is mandatory unless, in the crew's judgment, they

have reason to believe that they shouldn't carry out the

indicated action.

I

386
"(3 >,

CD CD

ID ._ CD ¢-

387
Slide 12

Types of Alerts Crews Receive

There are four basic types of alerts crews can receive. Time

critical alerts are those which the time to respond is extremely

limited and the response to the alert is the most important

action the crew can take at that specific time. A warning alert

is an emergency operational or aircraft system condition that

requires immediate corrective or compensatory action by the crew.

A caution alert is an abnormal operational or aircraft system

condition that requires immediate crew awareness and subsequent

corrective or compensatory crew action. Lastly, an advisory

alert is an operational or aircraft system condition that

requires crew awareness and ma__y require crew action.

388
oJ

n't

Im

nt_

¢n

t_

m

q,,=, 0

¢n

Q.

>,,

¢-

o_

(-

t,,--,

m

L_Eo_

I--

(D

E_

c-

(.-

(1)

m

¢.- 0

L_

(D

>., O>

"0

,<

,o

389
Slide 13

Looking at the "Nuisance" Problem

There are three types of alerts that generally fall under the

"nuisance" problem category•

i• Missed Alerts - Alerts not given but threat to aircraft

exists

Example - The aircraft enters a dangerous microburst with no

warning• The missed alert rate should obviously be held very

low.

• False Alerts - An alert caused by false indication or

system malfunction given when no threat

exists

Example - The aircraft receives a windshear warning on a calm day

when clearly no windshear exists. The false alert rate should be

quite low so as to not destroy crew confidence.

3 • Nuisance alert - Wind change or microburst is actually

detected but does not develop or

represent a threat

Example - The windshear alert is given for a microburst 3 miles

removed from the intended flight path or for a microburst that

exists 2 miles past the departure end of the runway when an

aircraft is crossing the threshold for landing. This nuisance

rate should be at a rate acceptable to the crews and is probably

at a "to be determined" rate.

390
_c cL

391
Slide 14

Windshear Issues Document

All participants at the First Combined Manufacturers' and

Technology Airborne Wind Shear Review Meeting should have

received a windshear issues document. The purpose of this survey

document is to help determine the priority of research on crew

information issues involving advanced windshear detection

equipment. The responses to this survey will help identify crew

information issues and those issues of a critical nature that

need to researched in the near term. The future use of this

document will be the incorporation of the issues into an R-bases

software data base for easy access by industry and government.

This readily accessed data base will allow the information

exchange necessary to help industry develop windshear systems

with the crew's needs understood.

392
E-, ' m OOa/

"O

U3O

c'}

=3

13_

t-OO

>._

o_O

o_

13..

(D

E3

(/)

>,,

o_

¢-.

(D

13 (D

=3

U..

_J3

(DOO!

>..,

"O

(D

"13>O

13_

O3

c'- 0X

£DC0E0

r- m

393
Slide 15

Issues Document Limitations

The survey of crew information issues was developed with several

limitations imposed. These limitations include: forward-look

orientation, no involvement in FAA regulatory changes, not sensor

specific, reactive devices are incorporated as part of an overall

advanced windshear system, involvement to be centered around the

man-machine interface, and the scope limited to airborne systems.

394
0

•i (D

mi.. (I_

cO

|I

o

E

0

c

0

Q.

-o

o E e _=

"F > (D (D

_ -6 c >

"-- ._ _ 0

o o o • >

•--- LL Z Z nr"

E

>

i

0

>

c

,I

-O

Or)

.0

I

"(3

.4_. C

0

E.I

J

395
Slide 16

Conclusion

This presentation stated how Boeing is involved in a NASA

contract to conduct windshear studies, in particular the Flight

Deck Research Groups' effort. A review was given of the

importance of understanding nuisance and alerting when related to

the development of forward-look technology. Finally, the crew

information issues document was presented and the importance of

identifying key issues stressed.

396
E0c

C_ Co_0

rn

Or)

"0C0cZ

CE00

om

_c0

CD

CD

rr

s

397
A Survey to Help Determine the Priority of Research on Crew

Information Issues Involving Advanced Windshear Detection

Equipment

I. Introduction:

This survey is part of a program to determine the focus and

priority of research efforts involving advanced windshear

detection. The flight crew has many information sources

available to cope with dangerous windshear situations. These

information sources are expanding with the probability that lookahead sensors may be added to present windshear detection

capabilities. Understanding what information the crew needs

becomes increasingly important as flight crews seek, with the aid

of advanced sensors, to avoid entering hazardous windshear

conditions. The introduction of look-ahead sensors as a natural

next step in windshear detection reveals crew information issues

that need to be resolved. We must determine how much data and

information the crew needs and the integrated presentation

concepts, which consider pilot workload, that should be adopted.

The resolution of these issues will assist in the development and

implementation of improved windshear detection equipment.

II. Purpose:

This survey document is a compilation of crew information issues

to obtain opinions relating to hazardous windshear avoidance.

The results of this survey will be used to determine the priority

and focus of future research involving the crew interface with

advanced windshear detection systems. It is intended that this

document eventually will be a living report of the crew

information issues involving advanced windshear detection

systems. It will be updated to reflect research activities as

they effect the issues.

III. Objectives:

The objectives of this issues document are to help mature future

windshear systems by:

* Documenting identified crew information issues associated with

advanced windshear detection systems

* To provide requirements for research activities to address the

issues raised

* To sample opinions and provide a sampling document for

identifying issues of human engineering concern dealing with

windshear detection systems

398
IV. Scope:

The scope of this survey document is limited to advanced

windshear detection system crew interface and information issues,

problems, and requirements for implementation.

Identified issues will be addressed by NASA, FAA, and Boeing

Flight Deck Research for possible research funding and issue

resolution. Please feel free to add any additional issues you

feel are important and the appropriate rating that issue should

receive. Return the completed crew information issues survey to:

Dave Carbaugh

Flight Deck Research

Boeing Commercial Airplane Company

P.O. Box 3707, MS 66-25

Seattle, Washington 98124-2207

Phone: 206-237-7286

Please return your survey by 1 December 1987 and indicate if you

would like to receive a copy of the results.

Your time and thoughtful responses to this survey will be greatly

appreciated.

399
Survey Definitions and Limitations

Definition of issue ratings:

On the next page starts a list of crew information issues

involving advanced windshear detection systems. This list is by

no means complete. Please rate each of the issues into the

following four categories.

CRITICAL

* Issue resolution required prior to industry-wide

implementation of look-ahead advanced windshear detection systems

SERIOUS

* Should be resolved prior to industry-wide implementation of

look-ahead advanced windshear detection systems

DESIRABLE

* A resolution of an issue could be expected to improve the

physical and/or operational man-machine interface

No Opinion

* Issue not applicable or unclear

The limitations of this survey are:

* The focus of this survey is on the incorporation of forwardlook technology on airborne platforms (although ground

information will form a factor in the crew decision making

process, our focus is on airborne systems)

* Issues should be involved with the man-machine interface (from

the instrument panel to the pilots and back)

* Issues should not directly require FAA procedural changes

* Issues should not be sensor specific

* Present day reactive sensors are considered to be non throwaway technology that would be incorporated as part of any

advanced windshear system

f

k

400
Crew Information Issue List

Name

Organization

Ratings- C=Critical

S=Serious

D=Desirable

N=No Opinion

In the area of displays .....

I. What is the benefit to crews to have

look-ahead capable windshear systems identify

non-critical shears (those shears with

thresholds below present alerting levels)?

2. Would crews benefit from actual or

derived look-ahead wind velocities being

actually displayed to the flight crew?

3. How far in front of the aircraft does the

crew need to receive windshear information to

make avoidance decisions?

4. How far displaced from the centerline of

the flight path do pilots need to see

windshear information for safe takeoff and

approach?

5. At what points, given a look-ahead sensor

detecting hazardous windshear during an

approach or takeoff, would crews benefit from

guidance commands for conducting escape

maneuvers?

6. What would be the benefits to crews to

have forward-look windshear information

displayed in a three-dimensional manner?

7. Can windshear look-ahead warnings and

information be integrated into present day

electronic and conventional flight deck

displays?

8. What would be the benefits to crews to

have microburst movement information

displayed using look-ahead windshear systems?

Ratings and Comments

401
Name

Organization

9. What would be the benefits to crews to

have look-ahead raw wind information( as

compared to relative wind/energy information)

displayed by forward-look devices?

In the area of controls ......

i0. What benefits can be gained by crews by

being able to control the look-ahead field of

view for takeoff or approach to avoid

hazardous windshear?

ii. What are the benefits to crews to have

crew selectable look-ahead parameters( field

of view, range of view, look-down angle,etc)?

12. What are the optimal crew operating

procedures for use of look-ahead windshear

information?

13. To what extent will pilot control of

windshear system parameters make the lookahead windshear system more acceptable to

flight crews?

In the area of alerting and crew interface...

14. What benefits can be gained by crews if

look-ahead capable windshear systems alert on

energy increasing shears?

15. What benefits do crews gain from being

aware of total magnitude wind changes even if

the rate of change of the shear is not

dangerous?

16. What windshear system nuisance alert

rate is acceptable to crews using look-ahead

capable windshear systems?

("Nuisance" means shear exists but is not a

factor to the crew because of location of

shear or changing intensity of shear.

"Acceptable" means crews react to the alert

in a safe manner.)

Ratings and Comments

4

402
Name

Organization

17. What look-ahead capable windshear system

missed (system fails to detect shear) alert

rate is acceptable to crews?

18. What look-ahead capable windshear system

false (system error - shear does not exist)

alert rate is acceptable to crews?

19. Do crews react to look-ahead windshear

warning alerts in an executive manner or in

an advisory manner?

("executive" means crews are required to

follow guidance unless they have reason to

believe that they shouldn't. "Advisory"

means crews follow guidance only if they

have some other reason to believe that they

should.)

20. What benefits would crews have if

reactive windshear systems alerting

thresholds are rescheduled by look-ahead

sensor information?

21. At what altitude does the crew no longer

need windshear alerting or look-ahead

information for takeoff and approach?

22. What would be the benefits to crews,

given look-ahead information, of "avoidance"

maneuvers in other than the vertical plane?

23. What level of interaction between

forward-look displays and present day color

weather radar displays produces the greatest

crew awareness of the windshear hazard?

24. What are the benefits to crews if

alerted on positive (energy increasing)

shears of the same magnitude as negative

shear alerts detected by look-ahead sensors?

25. How do crews react and perform given

windshear alerts on an aircraft that normally

carries a look-ahead system and a reactive

system and one of these systems are known to

be inoperative?

Ratings and Comments

403
Name

Organization

26. What would be the benefits to crews to

use voice in look-ahead situations for crew

alerting?

27. What are the effects on pilot

performance given a look-ahead windshear

alert in instrument conditions as compared to

a clear air dry microburst situation?

28. What are the tradeoffs in crew

capability and reaction to either warning

alerts given by forward-look devices or

caution alerts given by forward-look devices

as related to the distance to the windshear

hazard?

29. What are the effects of the increased

response time available to the crew with

look-ahead windshear detection equipment?

30. What is the effect on response time and

accuracy to a reactive system when look-ahead

information is used as a precursor to the

reactive alert?

31. What is the influence of achievable

precision of look-ahead sensors on total

effectiveness of the windshear detection

system?

32. What are the benefits to crews of

various update rate capabilities of lookahead sensors?

33. What are the benefits to crews in the

tradeoffs of increased accuracy as compared

to range capability of look-ahead sensors?

OTHERS..

Ratings and Comments

1

404
OPENING REMARKS

Herb Schlickenmaier

Friday, October 23, 1987

Why are we here? For two reasons. One is to provide an opportunity to

transfer the ongoing results from the NASA/FAA airborne program to you, the

technical community. The second reason is to pose problems of current concern

to the combined group. Up until now, we have met in two distinct groups. The

Manufacturers' Review Group has met three times. Our topics have ranged

from the first public presentation of the Bowles(F)-Factor, a fundamental

definition of the effect of wind shear on the aircraft, as well as providing a

forum for open discussion of the FAA's AC 25-xx. The Forward-lx)ok Technology

Review Group has met once. At that review, we were able to discuss the three

top contenders for forward-look technology, namely: infrared, lidar and

microwave radar. Further, the meeting centered not only on these sensors, but

around a common definition of the hazard and discussion of how a forward-look

device could be used on the flight deck. A thread between both of these

groups has been the definition of the wind shear hazard.

At this first meeting of the combined review groups, I see a unique

opportunity for cross-fertilization. Although the two groups work to address

different aspects of the wind shear threat, we speak the same language: a

common knowledqe of the effect of wind shear on aircraft performance. Now the

opportunity exists for the manufacturers to review the very latest in

forward-look technology concepts. Now the foundation is laid for the

technologists to gain from the experience of the manufacturers' development

and certification programs. Forward-look and reactive devices are no longer

competing concepts, they are allies in combating a common threat to aviation

safety.

Yesterday you heard the technical essence of the national airborne program.

Today we will go into some of the related areas: a review of the FAA

Windshear Training program; a quick look at what has been going on in the

Ground Sensors arena; an early look at a Terminal Information

System-related project at Ames Research Center; a status report on various

Airborne certification and regulatory efforts and a discussion of how we

miqht extend our knowledge and experience to the general aviation co.unity;

and, finally, insight into the massive effort required to establish a national

wind shear Meteorological Characterization data base, by examining the FAA

Technical Center's experience with their atmospheric data bases.

The agenda is full. The work is not yet complete. Both with the dialog that

we have established and our common goal fixed, we can expect nothing less than

success.

405

WP2318H page 1

I_NS - FAA/APS-430
%X;indsheur Truinino Kit

Volume I

%_'xndsheur

Munogoment

Overviexx-

%_'indsheor Pilot Guide

Exomplo NA'indsheor

Truining Proorum

Volume 2

SubsLuntiuting DoLo

XS'indshoor _voidod

%S'indshoo_ SS'hut the

Cro_" (]on Do

_i_. _ _ _

90 3Smm oomponion to

'Exumplo XX'ind_hoor

Troining Pr_g_[lm'

., _ ,,,c_ ,__., _,_<____._,<__AJ._YL__ _,_,_U_j£J,' t

ORIGINAL PAGE IS

OF POOR QUAIA'I__

406

page 1

i_.W_ _chiickenmaier, FA/_,/_,PS-430
Disl, rillulAon

121 Operutors

SGhedulod-188 Oporotors

p0rs for 121 ond 131_

Regions und Centers

SpeGio! lnl_rest Groul_

for further

distribution

- _ 7 t'_T-. % pI rill ._,_ _. i_ _ tl I;'_-2 11 i;--; I II I; _ 11il i , _/, _ ,l_l_i ,",(_1 I,];-71It II i

Europeun Gustomers in

London, Mull 1987

to,- _,u_ _u_tomor_ in

Singapore, Juno 1987

Interested putties in

Souffle, _uqust 1!]87

!11 il q i_l ;_ .; ,_..1, _ ;_ 11 ,! i I P ;i ' l t ,-.'. 3 ;' _' '! ;: ' 'l 'l !; , _ !

_q _ ,_ _,.-_ _c==_,.: .._ _ _¢--%,_-.,,_ ,_ _,-__. I " "/' "";. "5 ": " "__ "-g ",r'-,"-',

,, '_a'_/ li ,i !] i l !1 I1 '". _/fl_,_'Nt ,, ;, it , _ ':-;i ;,-_i _ i' _[ -_,--IIP--'

lloforon_o: t_lGGgO

Txx-o xYoel_ delivor_i

Cost: 271].00 US Dollur_

OR/GINAL PAGE IS

OE POOR QUALITY

paqe 2

407 _ W 3chiickenmaier, FAA/AP3-4_O
£stoblishes o

Users

_DS

-_S'indsheor XS'outhor

Evuluotion

_- ProGoutions

_- ROGovoru-

_S'indsh_ur E_mlpe

Munuevor

Power

Pitoh

408

page 3

H. W. Schiickenmaier. F_iAPS-430
""\ A ttiot zalAz tdiot'isu,7!

 <ii . _ ,_"...... ¢_1;_./._,.'n :.':'t.!, / 07'1'_' (?_/,ttol tlet__btS. MaO'Ia,M20743-3701

WINDSHEAR TRAINING AID PACKAGE

sponsored by the FAA ORIGINAL PAGE IS

OF, P_OOR QU$_LI_

Multi-media package includes: 90 color slides,

2_3/4" videocassettes and 2 training guides

Order number: A16690 Sale Price: $275.00

p

HOW TO ORDER

You can purchase by official purchase order,

_asterCard or VISA, check or money order made

payable to the National Archives Trust Fund

(NAC). Please, allow 2 weeks for delivery.

This training package is not available for

rental or preview.

Handling Charges: Please include a $5 handling

fee with each U.S. order to be invoiced. U.S.

orders accompanied by full payment or charged to

MasterCard or VISA are exempt from handling fees,

unless special shipping is requested. For orders

to be shipped outside the U.S., include a handling

fee equal to 15% of the total order plus postage.

Orders must be prepaid in U.S. dollars or charged

to MasterCard or VISA.

SEND YOUR ORDER TO:

National Audiovisual Center

Customer Services

8700 Edgeworth Drive

Capitol Heights, MD 20743-3701

301-763-1896

Credit Card Orders Only: 800-638-1300

Admtm<h'rc, l hl tl,_. Y_ttt_,_t, tl Art I_tt ,'_ told R¢¢_Jrd_ .4dmtntMnttton

409
N88-17632

rr" WI

b- <W

cr W

_JOa

.J<ZW

b-- <<

LI.

LI_ O

{D<

b-

>-

rr0

cO I-- I--

D-< r,,. cO

< _, rr

rr rr0 _-

(5 LUm< rr

0_ ._ uJ

rr rn

o.._z0

rr -J I-- < _ 0 0 a rr" 0 0 < < z

rr'__ aJ

i-- m

_E

t,

411
09

UJ

_JDOWIO

09

09

b09<

n-

(DO

n"

G.

<<DaZ<

(.90

_10Z

LL! 0Z

LLI I

13_

t-- Z0

rr"

Li_.

1--

O9

(.9

!--

O9

rr" m0

rr" 0

_1<

ILl

._1

_1m>

O9

b-ZDIZ

09m

"I0_

LU

OO

nLU>Z

LUD

cO

b-<

cO

"In-O

(.9

_J<ZOuO

LU

LUO

CO

G:mO

n"O

COZ<

_J

13.

CO

UJ

CO

o0

I'"

412
ILl

0

Z

nO

LL

rr

UJ

n

na

i0

IJ,,,

..I

0

<

I,IL, l--

or)

rr

rn

0

0

N

"T"

I--

Z

ILl

rr

I--

U'J

_--0

__z z _

_ _Z _ O_

A vO _ _>

Z

0

• • 0 0 _ • 0

413
ORIGINAL PAGE IS

OF, tK)OR qUALITY
ORIGINAL PA:GE 1_

OE POOR QUALITY

IUJ

Z

O O m

_ Z Z _ 0

Z _ _ _ _ _

ow 0

_w 415

o ¢/) u)

o

0

"-" 0 0

CC _ I

x _ ,,"

w 0 _

Z I- ,_
U)

<Z

Q,,,

n-uj

_J

_:eu

<1['-_

w_

R.

_00

,tI

il

Mmmm

-" .I--

tU nr"

u. QZ

oO <N

Z a. uj -r"

<

a .Y" u.

Z Z_ 0

O_ <D

_- _.0 Z

(/) ZO:: uJ

immo ::) w< 5

0 :_> "

_ O _-Z .J

IX:

u.O Q¢3 --= --.I

Ol- O_ u-<l: << 0

_ Z_ Z

_- _og ___o

. Q

416

OR]GD$.AZ, PAGE *_

O_ POOR, QUALITY.
p

1]: _" _ !

•- _ :-

I

_ ° o I i

> > -',_ ",

LLi 0 • o'--I • A

cc 7__ I o#O II • _ • _"

J J ! I_ __'1". i,,'-TS= J I °I I

"_ .:- E o e o o__ "" _tb I",.

m _ " _ o " ° ''' " _o'2q, o'l' 't,,,, •

o'-. _ . •

X- " • • oO-a 'r P_ I -

\ oj -o.. ,_,_ _ •

._ - __ _......" _"_ '__ o ."L'.._?.'_- ,-_...... " .......

_:..a • \ I •

.rr _'I

0 _ • \'J- O.,o

\

__0

0

0

_J

\

E

0

m

E

0

(0

I I

.. ,,. -- .

417
!

Z0W

O. 0

(J

I--

LUZ0

¢0W

b-0o

m

b-i IgIoLm

11IZ0m

bC)i

M.m

b-W0mI

m0

_i

III

i

"0

L_o@

v

u)

b-o

a:o

14J--

U_

J

.C-!

0 U_

00m

----_ _-I --ii emm,,,,__

u

I,-

c_

144

u,I Q

,,-,I

CC:

C_Wo

Q

418
y.

I

I

o

0

o

° .,-e* OR.gQg4qA!] PAGE [S

Og POOR QUALITY

419
0

Z0

4

o

0

0" V

!--,-

I lit

420
Rolmrt lie. [

I)( )'F ,' I+'A A /l I n -86-40

Title Iflll Subtitle

Cq:' rL,, ,r_, _+ D ;'r-_e

2 _rN_m Acc._u.. No

Prelimimlry Memphis PAA/'l.hlcoln l+alioratory I)pcrath)nal Wealh<-r

Studies Hesuhs

R.E. Rinehart, J.T. DiStefano, and M.M. Wolfson

. pel-l_mlll I Ollallllabll llama aliitl Addreu

Lincohl Laboratory. MIT

P.O. Box 73

Lexington, MA 02173-0073

Swing Aglincy lillmo end AIIdlesl

Department of Transportation

Federal Aviation Administrath)n

Systems Research and Development Service

Washington, DC 20591

TECHNICAL REPORT STANDARO TITLE PAGE

] Rlicillom'S CItiilt I lie.

Report Dill

22 _liril 19117

5. Pida;mmg 0tglilmzliliosl Cilia

I. Part¢rr:_ I 0rllimzlill<m Roper1 No.

ATC.14I

tO. Wilrk Umt _o, (IRAISI

11. Contract at Gram lie.

DTFA-01-80- Y- 10546

13 iypI el Report end Pitied Covered

Pr{_jcct Ih_'po r t

14, Siting Age+Icy Godl

]. $uliplemanllir I agates

The work reported in this document was performed at I,im'oln i.ahoratory, a center for research operated

by Massachusetts Institute of Technul,_p_y ,,tder Air Force Contract FI9628-85+C-0(102.

AlmmKt

During 1984 and 1985 M.I.T. Lincoln Laboratory, under the sponsorship of the Federal Aviation

Administration (FAA) conducted a measurement program in the Memphis, Tennessee, area to study

low-level wind shear events and other weather phenomena that are potentially hazardous to aircraft

operations, with particular emphasis on those issues related to the Terminal Doppler Weather Radar

(TDWR). The principal sensor for the measurement program was the S-band FAA-Lincoln

Laboratory Testbed Doppler Weather Radar (FL2) which incorporates many of the functional

features of the TDWR. Both FL2 and a C-band Doppler Weather Radar operated by the University

of No h Dakota (UND) obtained reflectivity, mean velocity and spectrum width measurements with

a radar geometry and scan sequences to facilitate determining the surface outflow features of

microbursts at the anticipated TDWR ranges. A 30-station network of automatic weather stations

(mesonet) collected l-man averages of temperature, humidity, pressure, wind speed and direction,

and total rainfall, plus the peak wind speed during each minute; this system operated from about

March through November 1984 and 1985. Finally, the UND Citation aircraft operated two 3-week

periods during 1985, collecting thermodynamical, kinematical and microphysical data within anti

around selected storms in the area as well as providing in sits truth fur locations and intensity of

turbulence.

This report describes the principal initial results from the Memphis operatious, stressing the

results from 1985 when the FL2 radar was fully operational. These results are compared to those

from previous" studies of wind-shear programs, e.g., NIMROD near Chicago, JAWS and CLAWS near

Denver. During 1985, 102 microburats were identified in real time along with 81 gust fronts. One uf

the dominant results is that moat microbursts in the mid-south are we_; that is, they are accompanied by significant rainfall. This is in contrast, for example, to the results from Denver where more

than half of all microbursts have little or no appreciable rain reaching the ground. Aside from this

major difference, micrnbursts near Memphis were similar to those found elsewhere in the country in

terms of wind shear magnitude. The report also gives more representative results from the aircraft

operations and discusses the effectiveness of the groun I +h,tter filters used on the FI,2 radar.

7. K*i Wlrlill

me_onel

Doppler ra<lir

rnicrobur.t

_ind shear

gust front

Termh|al Doppler

Weather Radar

I'lisle# (of _ tlpel'l I

NEXRAD

turbulence

chiller suppresBion

I,ow-'Ahilude Wind Shear

aviation wea4her hazards

Uuclassified

FORM DOT F 1700.7 (8-69)

ZO. $*cl._ Chlaid. (el m._ line. I

tim'lassi fit'd

1ll (}_ttlllltlois Stlalmln_t

l)ocunlent is available tr) the public throngh

the National Tc,'hnical Information Service,

SpringfichL VA '22161.

21. lie. of Pages Z2. Pri¢I 198

421 ORIGINAL PAGE IS

OF, POOR QUALITY
UNCLASSIFIED

SECURITY CL&$S|FICArlON OF _111 PAD|

REPORT DOCUMENTATION PAGE

ia REPORT SECURIFY CLASSIFICA_ION lb. RESTRICTIVE MARKINGS

Unclassified

2a. SECURITY CLASSIFICATION AUTHORITY

2b. DECLASSIFICATION/DOWNGRADING SCHEDULE

_4. PERFORMING ORGANIZATION REPORT NUMBER(S)

ATC-142

6a. NAME OF PERFORMING ORGANIZATION

Lincoln Laboratory,, MIT

6c. ADDRESS (CiW, State, and Zip Code/

P.O. Box 73

Lexington, MA 02173-0073

8a. NAME OF FUNDING/SPONSORING

ORGANIZATION

Department o| Transportation

Federal Aviation Administration

Systems Research and Development Service

8c. ADDRESS (City, State, and Zip Code)

Washington. DC 20591

6b. OFFICE SYMBOL

(If applicable)

8b. OFFICE SYMBOL

(if applicable/

3. DISTRIBUTION/AVAILABILITY OF REPORT

Document is available to the public through the National

Technical Information Service, Springfield, VA 22161.

5. MONITORING ORGANIZATION REPORT NUMBER(S)

DOT/FAA/PM-87/18

7a. NAME OF MONITORING ORGANIZATION

Electronic Systems Division

7b. ADDRESS (City, State, and Zip Code/

Ham<am AFB, MA 01731

9. PROCUREMENT INSIRUMENT IDENTIFICATION NUMBER

F19628-85-C-0002

10. SOURCE OF FUNDING NUMBERS

PROGRAM PROJECT TASK

ELEMENT NO. NO. NO.

471

11. TITLE (Include Security Classification/

Study of Microburst Detection Performance During 1985 in Memphis, TN

WORK UNIT

ACCESSION NO.

12. PERSONAL AUTHOR(S)

John T. DiStefano

13a TYPE OF REPORT 13b. TIME COVERED

Project Report FROM _.TO

16. SUPPLEMENTARY NOTATION

._one

14. DATE OF REPORT (Year, Month, Day)

1987, August 5

15. PAGE COUNT

4O

17 COSATI CODES

FIELD GROUP SUB-GROUP

18. SUBJECT TERMS {Continue on reverse if necessary and identify by block number/

low-level wind shear mesonet

microburst microburst outflow detection algorithm

Doppler weather radar radar/mesonet comparison

surface anemometers missed detections

19. ABSTRACT (Connnue on reverse Jf necessary and identify by block numDef)

This report focuses on the detectability of microbursts using pulse Doppler weather radars and surface

anemometers. The data used for this study were collected in the Memphis. TN area during the FLOWS* project of

1985. The methods used for declaring a microburst from both Doppler radar and surface anemomevpe data are

described.

The main objective of this report was to identify the results that were generated by comparing the 1985 radar

detected microbursts (which impacted the surface anemometer system) with the surface mesonet detected

microbursts. In so doing, the issue of missed microburst detections, for which there occurred two (both by the radar),

is identified. Possible reasons as to why these two microbursts were not detected are discussed in detail.

"FAA/Lincoln Laboratory Observational Weather Studies

20. DISTRIBUTION/AVAILABIUTY OF ABSTRACT 21. ABSTRACT SECURITY CLASSIFICATION

O UNCLASSIFIED/UNUMITED gl SAME AS RPT. El DTIC USERS Unelmmi(ied

i

22l. NAME OF RESPONSIBLE INDMDUAL 22b. TELEPHONE (Include Anm Code) 22¢. OFFICE SYMBOL

Msj. Thomas J. Alpert, USAF (617) 863-554}@, x-=330 ESD/TML

_M 1473. _ U_m,.-_i" "" '_"_ " " 422 UNCLASSIFIED

:._t¢ICINAL PAGE IS

OF PQOR QUALITY.
0

\

\

0

a,. • •

im

0

Z --J

C83 LLL

LLL rT- ._

n- _ "J

I,

-I

4"

u.n

ml

E

Z

F--

m

o_

L._

ii

I_ _.oo_ QUkLtTy

423
p • Q •

• 2 0 • • O O 0

0 ° • o % •

• • • gO • •

• • • Q E

• = • **o_ -'. : o. -..

_ • _"TIo = " • o • 0 0

" • • • " IX) CO o _. - .. ..-'._-. o. -o ," "_w

_ - , _-; . ...-. ,

IX: _ • .:• Oo • Ill 1;...- _ • • II • • • •I •

::) -J . •--:. .::_..-_-.-:.-..

- _._. :........ _

o _ _ - "t'."• Q . " "

IpI_INI Ilmmll • o _ln_ . ° .0 .

>= • . _ .

OD

01

q,,,-

'424
I--

:D

(D >-

0,_

On-

-- M.I

IK:

Z_

0"-.-0

I.- _-

I--o

g I

....q

_J

J

.'_"

._.

I

m

• ..•°•

m

u

U.I

,-1

!

2"

II:

IJI

m

I

I

°e

• I""I

....I_

m

lie

u_ >0Z

I,- 0

n

O.

ILl

m

==1 Z

O.

425
426
o

A

w

Z

_0

u.I

I-, ,-I

[.-,

,.4 _ ,q ,-4 _ _ e_

.J ,-I ,.-I ,.-I U U U ,.-I ,-I

Z Z Z

t".- [-,_

[.,.q "-" a,,

2:

< u u u _ < < u <

_ I '_ 0'_

• o . ° .

,'4 c5 o ,.4 ..-, ,.4 ._, o ,-,

v v v v v v v v v

I I I # I I I I I

'_' 0 0 0

0 0

',,-, U,

_ 0

_ _ _ o

_ I I! I III I

_ O_ 0 _0_

I I I I I

< < < < <

° °

v v

v

e'_ 0 0 C",I

('_ _ 0 _'_

I I I I

.,I ..1 ,..I ,.-i ,-I

--I ,-I .-1 ,.-I ,.-I

< u < _ <

°

o _i c,i

v v

0 _ 0 _

I I I I I

0 _ _ _

• o

•-,_S _r _ V -._-

vv _ v v v

t"- 0 _ _ "_ t'-

I # I I I I

I I I I I I I I I

< < < < < < < < <

,-, ,-, < <

427

O_ _OOR QUALI_
c

o

°_

u

r--

tD

n_

c_

O_

>

,-- c-

.0 u

cO'tO

_D. cOJ

C_ O_

fv,I ._'

U

0 0,)

::::5

°w,,--

e-.

o_1

..Q

I--

>

°_

¢-

U

¢_

0

0

_J

cn

t-

°_

u

QJ

cf-3

C3

tO

°,,-.

U

_J

¢0

0

Z _ _ _

-

Z_ __Z__ZZ__

U_

.<

O 3=:

Z "-_ J

¢./'_ t/3 ¢.._ ¢/") ¢.z'_ ,"_ O Z .._ o"_ ¢.,,o _J, ¢J, ....J Z Z _ ¢._

::D

m_mNm_oz<m__zzN

_-_ _n

+-_ _ u _D

0 _+_ 0 0

Q; E Q,; 0 ,_ ¢_ U O0 _,-- ,'--

U E _ _ £-- _ ._' u") _ _

_ _ _.

_ _- __ - _ > _ >

_ < -_ U -_ _ _ _ _-_ 0"_

428

OR.[GUqAL PAGE IS

OF POOR QUALITy
4

1. REPORT NO.

NASA TM- 4006

4. TITLE AND SUBTITLE

TECHNICAL REPORT STANDARD TITLE PAGE

2. GOVERNMENT ACCESSION NO. 3. RECIPIENT,S CATALOG NO.

SPACE/COHMEX DATA INVENTORY DOCUMENT

5. REPORT DATE

August 1987

6. PERFORMING ORGANIZATION COOE

7. AUTHOR(S) B.PERFORMINGORGANIZATIONREPORr •

• S. F. Williams, *H. M. Goodman, *K. R. Knupp, & J. E. Arnold

35812

9. PERFORMINGORGANIZATIONNAME ANDAOORESS

George C. Marshall Space Flight Center

Marshall Space Flight Center, Alabama

_,2. SPONSORINGAGENCYNAME AND AOORESS

National Aeronautics and Space Administration

Washington, D.C. 20546

10. WORK UNIT NO.

M-566

I I. CONTRACT OR GRANT NO.

3. TYPE OF REPOR'," & PERIOD COVERED

Technical Memorandum

, 14. SPONSORING AGENCY CODE

IS. SUPPLEMENT_Y NOTES Prepared by Structures and Dynamics Laboratory, Science and

Engineering Directorate

*Atmospheric Science and Remote Sensing Laboratory, Johnson Research Center, University

of Alabama in Huntsville, Huntsville, AL 35899

16. ABSTRACT

During the period June through July 1986, NASA conducted the Satellite

Precipitation and Cloud Experiment (SPACE) in the central Tennessee, northern

Alabama, and northeastern Mississippi area. In addition to SPACE, the Mlcroburst and

Servere Thunderstorm (MIST) Program, sponsored by the National Science Foundation,

and the FAA-Lincoln Laboratory Operational Weather Study (FLOWS), sponsored by the

Federal Aviation Administration, operated concurrently under the acronym of COHMEX

(COoperative Huntsville Meteorological EXperiment). The COHMEX field program

incorporated measurements from remote sensors flown on high altitude aircraft (ER-2

and U-2), Doppler and conventional radars, rawinsondes, satellites, cloud physics

research aircraft, and various surface observational systems.

This document contains a brief description of the field program and a daily

data collection summary. Chapter 2 summarizes the program instrumentation and

facilities, and includes sample selected data products. Chapter 3 provides a

meteorological summary, operations overview, and an inventory of the data collected

for each day of the field program. The purpose of this document is to provide the

researcher and scientist with a tool to select data sets for case studies and

instrument evaluation.

ORiOINAL PAGE IS

OF POOR QUALITY

17. KE_ WOROS

SPACE

COHMEX

MIST

FLOWS

Data Inventory

Meteorological Observational System_

19. SECURITY CLASSIF. (od th|a repa.ltl

Unclassified

_FC- Fozm llt| (i_,. _ber I|15)

_E'U.S.GOV(RNM(NT PRINTING OlrlrlC(*l|llT_TZ4-lZ$/lllllOtl

18. DISTRIBUTION STATEMENT

Unc lassi fied/Unl imi ted

Subject Category: 47

20. SECURITY CLASSIF. (or thle Pile) 121. NO. OF PAGES [ 22. PRICE ified [ 480

B

Fro' _le by lq'aaossAI Teelm_al lntormaUon Se,,_ee. Sprln6_eld, V_da 2 2161

429
p-,-:

• surface weather stations

• ',,_ • ,

FL-2 _adar

Low-Level Wind Shear System anemometers

4

Terminal Weather Sensors Near Stapleton Airport for FAA 1987 Wind Shear

Measurement Programs OR'{C:_+CAL PAC, E I_ /

430 OF POOR QUALITY
CO)

ILl n

\

P,

¢lB

m>n

#. --

UJ a

(DO

431
<[

UJ

o

r_

-o

o

u.

'T >

! I 1 1 I v

0 0 0 0 0 0

UJ

>

Z

LU

Q

0 CO qD ql' eq

$JI.N@q_JI ISN9

_1,0 tI_IHINN N

r,,,

G0

432
I

Z

_0

_o (3o co 0 0

• o

W

_; Z Z

I--,

,-I ,--1

r-- {-,C_

ul;_ b-, b-,

<

2;

0

[.., . _ o o

_ v v v

_ v

o,I 0 w') _ _-_

c,a o o o (-a ,_

I I I I I I

• ° ° •

Z

_ 0 0 0

| | I I | !

o o u u 0

c)

,<

C_

<

>

<

<

v

_o

° _,

, '7 _7 '7

0

,,4

0 0 0 _ .-..i (',I 0 0

<7 _7 o o o o o o

I I I I I I

c_

ua _ LJ El _ ua

I I I I I I

< < < < < <

e'_ _ _ 0 _r

< < < < _ Z Z

I I I I I I

< < < < < <

(._

ILl ILl U._ >.,

Z Z Z _ 0

433
.....?:.i:i:.::? --:. ::::.-:

.:........::::

.:....:...::

i13i:::

:.::!::.::

.........

.:.::::::::::::

_:....iiii!!i!ii_

:_iiiiiiiiiiiiii

:::i::.i:::::!:!::!.i

.: ;.::.:.:

:.:-:.:-::_::.
435
ORIGINAL PAGE IS

OF POOR QUALITY

436
Z

Om

pnp-

(I)

Z

0

W

a

W

rr

nO

LL

Z

0

rr

LL

Z

0

0

E

G)

JO

nc

_C

0

Z

II

ORIGINAL PAGE I8

OF POOR QUALITY

eO°_

o-oo

O

C

g) O

"" tl3t_

"61

_- _[

ca. --_cx I

O') _ -

_Oo °3

IIII

o_

o'_

.,:, 0, o

E o

>,oO _

,-O

o<

437
24 June 1987

INFORMATION PACKAGE

FAA Doppler Weather Radar Tests

Denver, CO

Introduction

The Federal Aviation Administration (FAA) will be conducting an experimental measurement program using pulse Doppler weather radars during 1987

around Stapleton International Airport, Denver, CO to obtain information on

low altitude wind shear phenomena and other terminal aviation weather

hazards. The objective of the FAA measurement program for 1987 is to

develop and validate techniques for the automatic detection of phenomena

such as microbursts and gust fronts, turbulence and heavy rain. The

results of this development program will be incorporated into the hardware

and/or software components of the Next Generation Weather Radar (NEXRAD)

and the Terminal Doppler Weather Radar (TDWR) systems which are being procured by the FAA.

A principal objective of the program is to develop techniques for

detecting low-altitude wind shear* events which are potentially hazardous

to aircraft taking off or landing at an airport. A particularly dangerous

wind shear situation occurs when a microburst, or downburst, from a storm

spreads out horizontally on reaching the ground as illustrated in Figure 1.

When an aircraft encounters such a wind situation, there is often a rapid

change from a headwind, which increases the lift of the airplane, to a tail

wind, which reduces the lift of the airplane. In extreme cases, the sudden

loss of lift from the tail wind can cause the airplane to crash.

Encounters with wind shear events may have contributed to as many as

25 aircraft accidents worldwide over the past 10 years, resulting in over

500 fatalities.

Wind shear events can be caused by a number of meteorological

situations. Thunderstorms often produce strong outflows and downdrafts

which can spread out upon hitting the surface. Large thunderstorms are

capable of producing long duration outflows, the leading edge of which are

called "gust fronts." Gust fronts can extend several miles away from the

rain area and last for periods as long as an hour or more.

Small storms and even relatively innocuous looking clouds are capable

of producing small but intense downdrafts which can be just as hazardous

(if not more so!) than those of their larger cousins. The smaller storms

produce what has been termed "microbursts" by some scientists. These

microbursts are often only a mile or two in diameter and last for as little

as 5 minutes. Nevertheless, if a microburst were to occur near an airport

while an ail "raft is taking off or landing, an accident could result.

*The term wind shear is used to describe situations in which the wind

encountered by an aircraft changes rapidly along the flight path. Not all

wind shears are hazardous.

438
ORIGINAL PAGE IS

OF POOR QUALITY

Cloud Base \ _ looo

Virga o_ i---*" I

I "pp'== so==

Rain , ! o

Downdraft

Outflow Front

IA

Horizontal "

Vortex

....... =".!7@i

Outflow

1000

Figure 1. Symmetric Microburst. An Airplane Transiting the Microburst Would Experience

Equal Headwinds and Tailwinds.

439
Low-altitude wind shear measurement and detection programs have been

conducted at a number of locations (Chicago, Denver, Memphis (TN), and

Huntsville (AL)) over the past few years. Denver was the site for:

. The Joint Airport Weather Studies (JAWS) project, a study of the

basic physics of microbursts conducted during the summer of 1982,

and

. The Classify, Locate and Avoid Wind Shear (CLAWS) project, in

which real time wind shear warnings were provided to the FAA

control tower at Stapleton Airport during a 45-day period in the

summer of 1984. The warnings were produced manually by research

meteorologists from the National Center for Atmospheric Research

(NCAR) who monitored data from a research Doppler weather radar.

The warnings were provided to controllers who then informed pilots

of hazardous weather events. CLAWS demonstrated that properly

interpreted Doppler weather radars could provide operationally

useful warnings of low-altitude wind shear.

The Denver Area Measurement Program

The measurement program in 1987 focuses on transitioning the scientific and operational knowledge gained in the previous measurement programs

to a fully automated wind shear detection system.

Figure 2 shows the locations of the various ground weather sensing

systems being used in the 1987 measurement program. The FAA test-bed

Doppler weather radar developed and operated by the Lincoln Laboratory of

the Massachusetts Institute of Technology (MIT) for the FAA will be the

primary data collection tool for the measurement program. This S-band

radar (designated by the letters FL-2 in Fig. 2 and shown in Fig. 3) uses

a 28-ft. diameter antenna and a powerful signal processing system to

record, process and display the Doppler measurements. This radar utilizes

certain advanced digital processing techniques (e.g., digital clutter

suppression filters and automatic choice of signal waveforms) which will be

required in the systems the FAA is procuring. The FL-2 radar will be

located on the Buckley Air National Guard airbase approximately 10 miles

southeast of Stapleton Airport.

The second Doppler radar used in the 1987 testing will be a C-band

system operated by the University of North Dakota (UND). This radar,

located approximately 8 miles northeast of Stapleton (designated UND in

Fig. 2), will provide additional confirmation of wind shear events near

Stapleton as well as enable the FAA to determine the effects of wavelength on the measured reflectivity of wind shear events.

, 440
O SURFACE WEATHER STATIONS

Figure 2.

A LOW-LEVEL WIND SHEAR SYSTEM ANEMOMETERS

Terminal Weather Aensors m,ar Stapleton Airport for FAA 1987 Wind Shear Measurement Programs.

441

ORirGT3I_L PAGI_ I_

OF POoR QUALITy
A network of 30 automatic weather stations (denoted by circles in

Fig. 2) located in open areas is collecting data on temperature, humidity,

pressure, wind speed and direction and rainfall, 24 hours a day. Data are

averaged over l-minute intervals and transmitted from each of the stations

to the GOES-East geostationary satellite every half hour. The data are

downlinked and provided to the project scientists by telephone line or computer tape for analysis or display. The wind data from the weather stations are used to validate the wind shear detection performance of the

Doppler radars while the other weather station data are used to accomplish

meteorological analyses of the wind shear events.

Additional information on the surface wind characteristics during wind

shear events will be provided by data from the 12 FAA Low-Level Windshear

Alert System (LLWAS} anemometers located about Stapleton (which are

designated by triangles in Fig. 2).

UND is also operating its Citation jet aircraft equipped with instruments to measure the winds, temperature and humidity conditions near storms

as well as the numbers and sizes of cloud droplets and raindrops encountered within storms. The Citation aircraft will furnish the data on the

upper air environment associated with wind shear as well as direct measurements of turbulence to confirm the accuracy of Doppler radar-based turbulence detection algorithms.

The development and validation of algorithms to automatically determine

the location and intensity of hazardous low altitude wind shear phenomena

is a principal objective of the 1987 program. In June 1987, real time

testing of the microburst outflow detection algorithm and the gust front

detection algorithm will commence at the FAA test-bed radar site.

These algorithms, based on experimental programs and data analyses over

the p_st few years by researchers at NCAR, NSSL, Lincoln Laboratory, and the

University of Chicago will operate in real time on the FL-2 data processing

system with the algorithm outputs being displayed on a color display

workstation.

Researchers from NCAR, Lincoln Laboratory, and the National Severe

Storms Laboratory (NSSL) will perform an initial evaluation of wind shear

events and the algorithm performance in real time. A more detailed

assessment of the weather phenomenology encountered and the algorithm performance (using data from the UND radar and surface weather sensors as

well as FL-2 data) will be accomplished in post-measurement analyses.

The algorithms to be tested in 1987 have demonstrated operationally

useful performance on wind shear events measured by the FL-2 system in 1985

near Memphis, TN and in 1986 near Huntsville, AL. The microburst events

encountered in the humid southeast portion of the U.S. were typically

accompanied by heavy rain. By contrast, many Denver area microbursts are

associated with much lighter precipitation producing storms. Thus, it is

442
ORrGrNAL PAGE Ig

OF POOR QUALITy

t,

,,q

443
necessary to demonstrate that the algorithms have adequate performance on

Denver wind shear events before the automated wind shear detection products

can be provided to the air traffic controllers at Stapleton.

If an operationally useful detection capability is achieved against the

Denver area windshear events measured in 1987, the FAA plans to conduct a

full operational demonstration during 1988 in which automatically generated

hazardous weather warnings will be provided to controllers for transmission

to pilots.

Additionally, the 1987 program will explore the possibility of future

enhancements to the near term automated products. A group of researchers

from NCAR will review the FL-2 data in real time to determine whether

expert radar meteorologists can reliably predict the imminent (e.g., 5-10

minutes) occurrence of microbursts and/or the development of thunderstorms.

FAA Weather Radar Procurement

The Federal Aviation Administration is participating in 3 weather

radar programs. These are the Next Generation Weather Radar (NEXRAD), terminal NEXRAD, and Terminal Doppler Weather Radar (TDWR). The NEXRAD

Program is a joint effort of the FAA, the National Weather Service, and

the Air Force to develop and procure a national network of weather

radars.

The terminal NEXRAD Program involves the use of 17 NEXRAD units reconfigured for terminal operations and installed near major airports such as

Denver Stapleton, Dallas-Fort Worth, and Chicago. These radars will be

operated for an interim period until the TDWR is available after which the

terminal NEXRAD systems will be reconfigured as standard NEXRAD systems and

relocated to Alaska, Hawaii, and the Caribbean.

The TDWR systems being procured by the FAA will provide pilots and

controllers with an indication of wind shear and other hazardous weather

conditions. These systems will be installed at major airports beginning

about 1992.

The Denver test program supports all of these activities.

Details on the scope and time schedule of the FAA weather radar program

can be obtained from Mr. Donald Turnbull [telephone (202) 267-8429].

Additional information on the Lincoln Laboratory, NSSL, and NCAR participation in the above measurement program can be obtained from

Drs. James Evans [(617) 863-5500 X814-433], Dusan Zrnic' [(405) 366-0403]

and Cleon Biter [(303) 497-8937], respectively.

444
Reprinted from JOURNAL OF ATMOSPHERIC AND OCEANIC TEC'_NOI OOY, VOI. 4, No. I, .'_arch 1987

A_.d_a M_ Sec_

ORIGINAL PAGE IS

OF POOR QUALITY

Recognizing Low-Altitude Wind Shear Hazards from Doppler Weather Radar: An

Artificial Intelligence Approach*

St'EVEN D. CAMPBELL AND STEPHENH. OLSON

Lincoln Laboratmy, Ma._achu_ats Institute of Technology, Lexington. MA 02175

{Manuseript received 23 April 1986, in final form 12 December 1986)

_rl_cr

paper describes an artificial intelligence-based approach for automated recognition of wind shear hazards.

The design of a prototype system for recognizing low-altitude wind shear events from Doppler radar displays

is presented. This system, called WXI, consists of a conventional expert system augmented by a specialized

capability for p_n 8 radar images. The radar image p_ng component of the system employs numerical

and computer vision techniques to extract featu_ from radar daut. The expert system carri¢_ out symbolic

reasonintt on these features using a set of heuristic rules expressing meteorological knowledge about wind shear

recognition. Results are provided demonstratin8 the ability ofthe system to recognize microburst and gust front

wind shear events.

-7-c.)

1. Introduction

Considerable attention has recently focused on the

problem of detecting low-altitude wind shear hazards.

It is known that wind shear poses a substantial hazard

to aircraft, particularly on rake-offs and landings (National Academy of Sciences, 1983). Wind shear is reported to have caused major air crashes in 1975 and

1982 (Fujita, 1985), and is strongly suspected tobe the

cause of a more recent crash at Dallas in August, 1985

(Fuji_ 1986).

- .Because of the concern for aircraft safety posed by

low-altitude wind shear, it has been proposed to install

Doppler weather radars at major airport areas to detect

,these events (Federal Aviation Administration, 1984).

Research projects such as JAWS (Joint Airport Weather

Study) at Denver in 1982 demonstrated the detectability of microburst events by Doppler radar (Wilson

et at., 1984). The CLAWS (Classify, Locate and Avoid

Wind Shear) project in the summer of 1984 showed

that microhursts and gust fronts can be recognized in

real-free by skilled radar meteorologists using singJeDoppler weather radar displays (McCarthy and Wilson,

1985).

However, it is clear that the operational use of

Doppler radar to support air traffic control (ATC)

functions will require an automated wind shear recognition capa "'ity. First, not enough radar meteorr'

ogists exist t, monitor wind shear hazards at all, otential radar sites. Second, the task cannot be delegated

* This work was supported by the System Engineering Service of

the Federal Aviation Administrat/on (FA.A) under lnteragency

Agreement DTFA01-83-Y-10579. The information presented does

not necessarily reflect the official view or policy of the FAA.

to air traffic controllers because of the meteorological

expertise required and the increase in workload that

would be imposed.

The objective of the work reported here is to explore

the use of artificial intelligence techniques in weather

radar interpretation. Specifically, the goal of the project

is to develop a system which mimics the performance

of a meteorologist in recognizing low-altitude wind

shear hazards from Doppler radar displays. The WX 1

design employs techniques from artificial intelligence

and computer vision to achieve this aim. The rationale

for this approach will now be briefly explored.

2. Expert systems and radm"meteorology

Expert systems have gained much attention recently

as a technique for capturing the performance of human

experts in specialized fields of knowledge. Areas in

which expert systems have been developed include such

variedapplicationsasmass spectrogramanalysis,disease diagnosis,speech understanding,geological data

anaJysis, and computer configuration (Hayes-Roth et

al., 1983)./

The assumption behind these applications is that a

body of si_alized knowledge is-possessed by the human expert. Expert systems attempt to cal_Ure this

knowledge in an explicit form and employ mechanisms

to apply this knowledge to solve problems in the domain ofexpertise.Usingthisapproach, expertsystems

have been able to successfully perform tasks which

previously could only be carded out by human specialists. Moreover, expert systems have in some cases

been able to atu6n levels of performance equating that

of humans (Buchanan and Shortfiffe, 1984).

Given thegrowingapplicationofexpertsystemsin

© 1987 American Meteorological Society

445
6 JOURNAl_ OF ATMOSPHERIC VOLUME4

many fields, it is natural to ask how this technology

might be applied to meteorology. In particular, the

present project grew out of the question of whether an

expert system could be built to recognize wind shear

hazards from Doppler radar data. In order to answer

this question, it is necessary to examine the nature of

the task that a radar meteorologist is asked to carry out

in recognizing a wind shear hazard such as a microburst,.

First of all, it should be recognized that the radar

meteorologist's task has a large visual processing component. A typical weather radar display consists of a

series of color-coded images representing such products

as reflectivity and radial velodty. The meteorologist

must be able to recognize patterm in these images in

order to recognize a wind shear hazard. To do this, the

radar meteorologist makes heavyuse of the image processing capabilities of the human visual system. These

capabilities include the ability to discern regions, edges,

gradients, peaks and so forth.

Second, the interpretation task also involves the use

of spedalized knowledge. What appears as a collection

of meaningless colored blobs on a screen to the naive

observer is perceived as a microburst, gust front, storm

cell or other phenomenon by the radar meteorologist.

The specialized knowledge of the expert also allows

such artifacts as second trip echoes, velocity folding

and clutter to be rejected. In fact, recognizing these

artifacts is an important part of the interpretation proce_

The radar expert also uses meteorological knowledge

to guide processing in an adaptive fashion. For example, the divergent outflow signature ofa microbut_t

might initially be quite weak. However, the meteorologist may have some indication that a microburst is

about to occur, such as the observation of a descending

reflectivity core. In this case, the meteorologist is able

to recognize this weak divergence as a microburst indicator and therefore provide an early warning.

3. The WX1 system

It can be seen from the foregoing discussion that a

system which attempts to emulate the performance of

a radar meteorologist requires an approach which

combines symbolic reasoning with visual processing.

The basic problem confronting such a system is to refine the massive deta,_ of the input radar data into an

abstract representati Jn 3f meteorological phenomena.

A conceptual view of this refinement process is

shown in Fig. 1. The pyramid shape of the diagram

indicates that information is represented in increasingly

abstract and less detailed form as the processing proceeds. At the lowest level of the pyramid is the radar

data comprising literally millions of bytes of information. This mass of data is abstracted by the application of pattern recognition algorithms into a set of

image features numbering perhaps in the thousands.

AND OCEANIC TECHNOLOGY

/,...z.__\,

FIG.I. Concelm_ view of system vroo_inll.

These image features are then refined by knowledgeprocessing operations into a handful of identilied phenomena at the top level, such as microbursts, gust

fronts, storm cells and so forth.

a. Approach

The AI approach employed in the WX 1 system can

be contrasted with conventional techniques in two

main areas.First, WXI is broad-based. It relies on

multiple sourc_ of information and on multiple lines

ofreasoning. Second, WX1 is knowledge-based. It employs knowledge aboutwind shear structure, and about

radar artifacts which can lead to false .alarms.

The WXI system employs multiple sources of information to identify wind shear hazards. For example,

WX I uses both Doppler velocity and reflectivity data

to recognize gust fronts, instead of relying on a single

radar product. In one case, the gust front might be

most apparent as a shear line in the velocity field; in

another case, the gust front might be more apparent

as a reflectivity thin-line. Furthermore, WX 1 can use

results from one information source to guide pmceming

for the other sources.

WX 1 does not depend on a _ algorithm to iat_ret a given information source. Rather, it uses

multiple pattern recognition algorithn_ to extract few

tures from the radar data. For example, it uses two

"'q'erent algorithms to extract shear features from the

Doppler velocity product. Neither algorithm works in

all cases, but by using them together the system can

detect some shears that it would otherwise miss.

WXI performs knowledge-based classification and

interpretation of wind shear hazards. WXl contains

structural models which relate meteorological phenomena to features extracted from the radar data. In

addition to modeling these phenomena, the system also

contains models for radar artifacts which could lead to

false alarms. For example, an apparent shear line will

446

-,JC-rNAL PAGE IS

OE POOR QUALI'I_
MARCH 1987 STEVEN D. CAMPBELL AND STEPHEN H. OLSON 7

OBSERVER

EXPERT

.f--_

#qxliL8 Itl@lOme

I PROOUGTION RULE0 J

I :ll

FIG. 2. WX ! System Design.

be rejected if WXI determines that it matches the

model for second-trip echoes.

b. System design

The WX I system designconsistsof two major elements,as shown in Fig.2.The radarimage processing

clement containsthe numerical and image processing

capabilities of the system; the expert element contains

the system's meteorological knowledge and symbolic

reasoning capabillty. The two elements communicate

with each other by exchanging messages, with the expert generating queriesand the observer producing reponses.

The radar image processing element performs opelationson two databases.The first of theseisa radar

database containing the input data in Cartesian resampied form. This radar data includes primary radar

products, such as reflectivity, radial velocity and spectrum width, and derived products such as radial and

azimuthal shear.

The featuredatabase contains the image features

which have been extractedfrom the radardata.Italso

containshigher-levelfeatureswhich have been created

from theproduct-levelfeatures.At thetop level,itconrainsabstract features such as a microburstrecognized

over several succe_ve volume scans.

The expert system element consists of production

rules, a working memory and an inference engine. The

working memory contains a set of facts which represent

symbolically the contents of the radar and feature databases. For example, suppose that V1 is a Doppler

velocity field, and that FI and F'2 are features extracted

from that field, as shown in Fig. 3. Thus, V I is an

element of the radar database, and FI and F2 are elements of the feature database. The working memory

containsfacts which rq)resent these elements in symbolic form, such as the fact indicating F1 is a pOsitive

velocity feature.

The inference engine performs the task &matching

these facts to the condition part of rules. When a match

occur, the inference engine performs any required tests

J

RADAR AND FEATURE DATABASES WORKING MEMORY

v, _ VELOGIYY FIGLO -_

RADAR

F3

IXTRACTEO F_ ,

FIG. 3. Representation ofextractedfeaturesasfactsin working memory.

(RAOAR-.FNELO eV 1 :VELOIP:ITY)

(FEATURE F! ;POSITIVE-VELOCITY)

(FEATURE F 2 ;NEGATIVE-VELOCITY)

447
8 JOI'RNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY VOLUME4

on those facts by sending queries to the radar image

processing element. If all the tests are satisfied, the action part of the rule is then carded out. Typical actions

consist of asking the radar image processing element

to create a higher-level feature and to add that feature

as a fact to the working memory.

The partitioning of the system design into expert

system and radar image processing components allows

WX 1 to perform symbolic reasoning while retaining a

powerful capability for processing radar images. The

advantage of this approach is that it allows the details

of the radar data and image features to be hidden from

the expert system. Thus, a particular image feature is

known to the expert system as a region of a particular

type, such as a positive velocity feature. The size, shape

and other properties of a given feature are not known

directly by the expert system, but can be determined

by sending queries to the radar image processing subsystem.

c. System configuration

The WXl system is currently implemented on a

Symbolics 3670 Lisp machine with 4MB memory capacity and 474MB of disk storage. The hardware includes a monochrome console display, a high-resolution color display for radar images and a nine-track

magnetic tape drive for data input.

The software for the WX 1 system currently consists

of approximately 15 000 lines of Lisp code. Of this

total, about 10 000 lines or two-thirds are devoted to

image processing operations. The remainder consists

of the expert system shell and two rulesets, one for

microburst recognition and the other for gust front

recognition. At present, the microburst ruleset contains

about 150 rules and the gust front ruleset about 200

rules.

The expert system is implemented in YAPS (Yet

Another Production System), a production rule language similar to OPS5 (Allen, 1982). The image processing component is implemented with extensive use

of the Flavors object-oriented programming system

(Weim'eb et at., 1983).

4. Radar image processing

The radar image proce_ g component of the system

performs numerical and ccmputer vision operations

on radar images. These operations include processing

the input radar data, extracting image features and

performing various computations on features.

a. Input data processing

The input radar fields are currendy converted from

polar to Cartesian-sampled form by off-line processing

prior to entry into the system. A number of numerical

operations can bc carried out bv the WXl system on

the input radar data. One type of processing is to modify the radar data by such operations as filtering to

reduce noise, masking out regions and applying

thresholds to the data. Another class of operations is

to compute derived products such as radial and azimuthal shear.

b. Feature extraction

Feature extraction involves three stein: pixel classilication, connected-region determination and feature

instantiation. Pixel classification is based on an a priori

assignment ofpixel values to classes. For example, pixels in a radial velocity field are classified as positive

(>2.5 m s-_) or negative (<2.5 m s-'). The result of

this process are point maps of the classes for each field.

The connected regions for each point map are then

determined, resulting in a list of regions for each class.

c. Feature processing

Three types of operations can be carried out on features. The first type of operation is to answer a query

about the properties of a particular feature. These

properties include !) location (centroid, range to radar,

azimuth, altitude); 2) shape (length, width, height,

elongatedness, compactness); and 3) numeric value

(maximum, minimum, average).

The next type of operation involves determining relationships between features. The response to these

queries can be either numeric or logical. An example

of a numeric result is to compute the distance between

two features, e.g., the distance between the centroids

of features FI and F2 in kilometers. An example of a

logical result would be to compute whether features

on adjacent elevation scans overlap; in this case the

result of the operation would be a true/fal_ response.

The third type of operation is to create higher-level

features from lower-level features. A higher-level feature is created by the image processing package when

the expert element finds that there is a rem_n to group

features together. For instance, when the expert element

determines that features FI and F'2 constitute a velocity

couplet signature, it asks the image processing element

to create a velocity couplet feature from F1 andF'2.

This higher-level feature can also respond to queries

about its properties and its relationship to other features.

5. Knowledge processing

The function of WX l's expert system is to examine

and classify the results derived from lower-level pattern

recognition algorithms. The expert system contains

symbolic models of weather phenomena to be recognized. The low-level features extracted from the radar

448
MARCH 1987 SI'EVEN D. (',.\MPBELL AND STEPItEN H.

data are compared against these models to determine

the most likely classification of each feature.

This section will describe the nature of the meteorological knowledge used in the system. An example

ofhow rules are used to recognize wind shear phenomena is provided. Next, a mechanism for quantifying

the degree of certainty about the interpretation of features is discussed. This mechanism for reasoning about

uncertainty allows evidence from multiple sources to

be combined and selection of the most likely interpretation from a set of competing hypothese_ Finally the

control strategy used in the system is described.

a. Meteorological knowledge

The WX 1 system ruleset contains several types of

knowledge. One type of knowledge defines the weather

phenomena and radar artifacts which the system can

recognize. A second type of knowledge relates these

phenomena to radar image features. Other knowledge

defines the relationships between different weather

phenomena and the evolution ofthese phenomena in

time.

As an illustration ofthe first type of knowledge, consider Table 1, which shows the various radar meteorology phenomena recognized by the WXI system.

These phenomena are divided into "'storm" and

"shear" classes. The "storm" class contains two

sible types of phenomena: "storm event" and "storm

TAIlIJEI. Classification hierarchy for knowledge brae.

Storm

Storm event

Single-cell

Squan-tine

Super-cell

Storm artifact

Clutter

Range ring*

Range folcUnl

Shear

Shearevent

Linear gust front

Gust front

Inflow-outflow line

Ring gu_ front

Downbmst

Microbunt

Macrobut_

Divergent line

Mesocyclone

Shear artifact

Velocity folding

Range folding

False zeros t

Badradial*

High noise

• Datarecordingartifact

) Velocity zeros induced by clutter.

OP_"O/NA

• L PAO/_ [g

_F. POOR QUALITy

OLSON 9

artifact". The storm event subclass is thrther subdivided

into different types of events, including single-fell,

squall-line and super-cell. The storm artifact subclass

includes several types of spurious signatures that must

be differentiated from actual storms, including clutter,

range ring (a data recording artifact) and range folding.

The second type of knowledge expresses structural

models which connect meteorological phenomena to

radar observables. For example, Fig. 4 shows a model,

based on Fujita (1985), of a particular type of surface

microburst. In this model, a surface microburst consists

of a surface divergence, a middle-level rotation and an

upper-level convergence. Each of these phenomena, in

turn, is linked to radar signatures. For example, a surface divergence is recognizable from a velocity couplet,

a positive radial shear or both signatures.

Another type of knowledge defines the relationships

between different meteorological phenomena. These

relationships are important in distinguishing between

real phenomena and radar artifacts. For example, the

presence of a nearby storm can be used to help confirm

the existence of a gust front. Similarly, the presence of

a shear line associated with a gust front can be used to

predict the existence of a reflectivity thin-fine.

A final type of knowledge describes the time evolution of meteorological phenomena. For example, a

microburst begins with activity at or above cloud level,

descends to middle level and finally reaches the surface.

Thus, the presence of precursors at middle or upper

levels can be used to increase the confidence in a surface

divergence signature. Likewise, if a microburst is recognized in a particular radar scan, then the confidence

in that recognition should be higher if the microburst

was recognized in the same location on a previousradar

scan.

b. Use of rules

As an example of how rules are used in the system,

consider the problem of detecting a velocity couplet

signature indicating a surface outflow for a microburst.

A rule to recognize velocity coupletsmight then appear

(in pseudo-English form) as follows:,

(rule recognize-velocity-couplet

if FP is a candidate positive-velocity feature

FN is a candidate negative-_,ocity feature

distance betweenrFp and FN _ 4.0 km

test velocity difference between FP, FN _ 10 m s-t

create velocity couplet feature from FP, FN then

add velocity couplet fact to working memory).

This rule assumes that the velocity features are previously evaluated by other rules to produce a set of candictate or likely features on the basis of size, shape,

maximum value and other tests.

For the case shown in Fig. 3, the variables FP and

449
l0 JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY VOLUME4

|urf,ce middle

diver|once rotetioa

I I

d/vecgence rotation

/\ /\

velocity positive velocity positive

couplet radial couplet az/authal /\- positive negative

_eIocICy velocity

upper

convergence

¢oaverieaco

/\

velocity negative

couplet radial

positive negat Ive positive negative

velocity velocity velocity velocity

FIG. 4. Model ofa microbunt wind shear hazard.

FN would be matched up against features F I and F2,

in the "'if" part of the rule. The "'test" part of the rule

invokes the computation of the distance from Fl to

F2, and then checks that the result is less than 4.0 km.

It also checks that the difference in velocity between

the two featur_ is greater than l0 m s-t.

Iftheseconditions are fulfilled, then theactionpart

of the ruleiscarriedout.For thisrule,the actionsarc

to create a velocity couplet feature from FI and F2,

and add the corresponding fact to working memory.

This new fact can then trigger another rule which decides, based on its orientation, that the velocity couplet

represents a divergence. A new fact would then be

added to the working memory representing this divergence feature.

It can be seen that other rules can recognize rotation

and convergence signatures, and add the corresponding

facts to working memory. These signatures are further

classified as surface divergence, middle-level rotation

and upper-level convergence. These signatures can then

be combined by a rule to recognize the surface microburst.

c. Reasoning with uncertainty

In order to quantify the degree of certainty to which

a given feature represents a particular meteorological

phenomenon, each feature has one or more quantifies

associated with it called confidence factors (CFs). A CF

indicates the degree to which the feature is believed to

represent a certain type of wind shear hazard or radar

artifact.

A CF is a number ranging from - 1 to + 1. A positive

CF indicates belief in a hypothesis, while a negative

CF indicates disbelief. CFs from multiple lines of evidence can be combined to produce a net belief or

disbelief. Given two pieces of evidence, El and E2,

with associated confidence factors, CF(EI) and CF(E2),

then

CF(EI, E2) = CF(EI) + CF(E2)[ 1 - CF(E I)] (I)

assuming both CFs are positive. For example, ifCF(E 1)

= 0.2 and CF(E2) = 0.5, then CF(EI, E2.) = [0.2

+ 0.5][0.8] = 0.6. (Note: positive and negative CFs can

be combined using a more general version of Eq. (1),

as detailed in Buchanan & Shortliffe, 1984). Positive

CFs accumulate in a fashion which asymptotically approaches + 1, indicating increasing certainty as more

evidence is added.

The CFs axe used in two ways in the WX 1 system.

The first way is to combine evidence from multiple

sources to increase belief in a given hypothesis. The

second way is to select the most likely interpretation

of a feature from a set of competing hypotheses. Examples of theseuseswillnow be provi&xL

As an example of evidence accumulation,consider

the following hypothetical example in microburst rec,

ognition. Suppose that there are two confidence factors

ass,Joated with a surface divergence (outflow) feature.

The first CF is the result of a velocity differential test

and is denoted CF(DV); the second CF is determine()

by whether a precursor signature was recognized on

the previous volume scan and is denoted CF(PC). Suppose that these CFs ate defined by

= f 0.2, 5<DV<lOms -t CF(DV) L0.6, lO<DV<20ms -_

45O

U_uI:,_AL PAGE IS

OE POOR QUALITY
"-'-:.ltJI:'IAI.;PAGEIS

OF PGORQUALITy

MARCIt1987 STEVEN I). ("XMPBEL[. ,_,ND STEPItEN It. OLSON ll

0.0, no precursor on previous

volume scan

CF(PC) = 0.5, precursor on previous

volume scan

and that CT(MB) = CT(DV, PC) represents the confidence factor for the feature representing a microburst.

Now consider two cases. In case I, the velocity differential DV is 12 m s-t and there is no precursor on

the previous volume scan. For this ease, CF(DV) = 0.6

and CF(PC) = 0.0, so CF(MB) = 0.6. In case 2, the

velocity differential is only 8 m s-t, but a precursor

was present on the previous scan. For this case, CF(DV)

= 0.2 and CF(PC) = 0.5, so CF(MB) = 0.6 as before.

Thus, ff a CF(MB) of 0.6 is v/ewed as a definite microburst indication, it can be seen that the feature can

be declared as a wind shear hazard in both cases.

A further extension of this approach allows the system to consider multiple hypotheses while carrying out

the wind shear recognition task. The system assigns a

confidence factor to each hypothesis and then selects

the hypothesis with the highest CF. For example, the

system may hypothesize that a given shear feature represents a gust front, velocity aliasing_ ground clutter or

weak signal. Suppose that the system assigns the following confidence factors while searching for gust fronts

in a given tilt:

CF (gust front) = 0.6

CF (aliasing) = 0.2

CF (second trip) = 0.3

CF (weak signal) = O.I

In this case, the system would select the gust front hypothesis as most likely for this shear feature.

It should be noted that the performance of the WX 1

system is relatively insensitive to small changes in the

values assigned to the CFs. In fact, the system tends to

resist attempts to fine tune the CF values. This behavior

is due to the system combining many sources of evidence to arrive at conclusions, and also because it invokes additional rules and feedback operations to resolve uncertain features. Improved system performance

is achieved by adding more knowledge to the system,

rather than by attempting to tune the CF values.

d. Control

The WX 1 uses a combination of bottom-up (datadriven) and top-down (goal-driven) control. The basic

control strategy in YAPS is forward-chaining or datadriven, i.e., reasoning from premises to conclusions.

However, WX I also makes heavy use of goals to provide a hierarchical processing structure. This hierarchy

reflects the natural organization of the radar data into

datasets, volumes, tilts and fields. The goal structure

ensures, for example, that all fields (reflectivity, velocity,

radial shear, etc.) are processed tbr a given tilt belbre

going on the next tilt.

The interpretation process proceeds basically in a

bottom-up fashion, assembling lower-level features into

higher-level ones (ke., combining surface divergence,

middle-level rotation and upper-level convergence features into a microburst feature). However, the system

does generate goals in a top-down fashion in some

cases. For example, if a gust front was detected from

a shear line, then the system will generate a goal to

look for a thin-line in that region using a special algorithm that would not normally be applied. Also, if

a gust front was located on the previous volume scan,

the system will look for the gust front in that area first

on the next scan.

6. Results

Rulesets are currently being developed to recognize

two types of low-altitude wind shear hazard: microbursts and gust fronts. This section will describe the

characteristics of these hazards, their associated singleDoppler radar signatures, and some current recognition

results.

a. Microburst recognition

A microburst is a small-scale, short-lived event

characterizedby a strong downdraR which induces a

hazardous outflow of winds at the surface. Figure 5

shows an aircraft encountering a microburst while

landing. The combination of downdraR and loss of

airspeedwhilepassingthrough a microburstcan cause

excessive altitude loss and result in a crash.

Microburstsaredefinedtobe less than 4 km in initial

horizontal outflow extent and to last 5 to 10 min. For

a typical microburst observed in the Joint Airport

Weather Study (JAWS) project, the surface differential

velocity typically increased from 12 m s-t (25 kt) to a

maximum of 24 m s -t (50 kt) in this time interval

(Wilson et al., 1984).

Figure 6 shows the characteristicsingle-Doppler radar signatures associated with these flow fields. The

model of Fig,.4 discussedpreviouslyshows the conncction between these radar signatures and a microburst mode[ proposed by Fujita (1985). In this model,

a microburst is characterized b" a surface divergence,

¢middle-altitude (_ 1.5 km AG_) rotation and upperlevel (--2.5 km AGL) convergence. The ruleset includes other microburst models, such as a surface divergence accompanied by a high reflectivity rain core.

Figure 7 shows an example of a JAWS microburst

which occurred 13 km east of Stapleton Airport on 14

July 1982. The microburst began at about 1433 MDT

and reached peak intensity ten rain later (Stevenson,

1984), at about the time the data of Fig. 7 were collected. Radial velocity data are shown for scans at the

451
12 JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY VOLUME4

100

I

%, /

FIG. 5. Aircraft encounter with a microburst.

surface (tilt 1, upper panel) and at 2.1 ° elevation angle

(tilt 2, lower panel). The cursors show the location of

a surface divergence signature in tilt l and a middlealtitude rotation signature in tilt 2. The images are 256

by 256 pixels at a resolution of 0.25 km per pixel.

The first step in the microburst recognition processing is to extract features from the input radar fields,

For tilt I, the velocity and radial shear fields are extracted, while for tilt 2, the velocity and azimuthal shear

fields are extracted. Different fields are extracted for

the two tilts because the system is looking for surface

divergence signatures in the first flit and for middlealtituderotationsignatures in the second.Upper-altitude data were not availablein thiscase,so therewas

no attempt to perform extraction for convergence signatures.

The ruleset evaluates the extracted features, promoting likely features to candidate status, and labeling

the others as weak. The candidate features for each

field are shown in Fig. 8. lmtially, the feamra in the

velocity couplet signature are labeled'as weak due _o

theirsmallsize.However, _ featur_ arc lmamoUxi

to candidate status on the basis of their overlap with

one of the radial shear signatures. The velocity couplet

is then recognized as a surface divergence.

The candidate features for tilt 2 are examined in a

similar fashion.A middle-altituderotationisidentified

from one of theazimuthal shc_rfeatunm,but the corFLOW FELD8

Jlo TJ_ION

RAOAN

OUTFLOW

Q

VF.LOCffY _GNATI.mE8 SHEAR SIGN/lURE8

®0®

Q

Q

AzJmjlrl,¢_. Q

FIG. 6. Single-Doppler radar signatures of a microbum.

452

O:":I_3INAL PAGE Ig

OF, P.OOR QUALITY
,qI_ VF ",, (" \M PP, I ] L

'___ P_OOR QUALITY,

\ND S II!PIII x, tt ()t SON 13

oo

e.

O

e.n

O

O

0

e,i

O

,m

2

r_

.._

453
14 J(_IRN' \1. ()I \ I \I()Y, PItERIC _ND ()CEANI( TECHNOLOGY VOLUME4

C_alo*te atalal _ea, Feot.ros, r_lt :

I"

4

f

s/,_ "m

SURFACE

ONERGENCE

SK_IRURES

ca_144¢e veleSltv eeetvree. Tl|t 2 :_41eet* tz *v¢_*1 S_*r Feetvrn Tl_t 2

• . _[mUT**_L

./ shoal memm

FIG. 8. Surlhce and middle-altitude microburst signature.

MIOOLE-ALTrr'dOE

Ro'r_qlON

SIGNATURES

responding velocity couplet signature is not recognized

because the positive velocity feature is too large. However, the system then determines that the middle-altitude rotation overlaps the surface divergence, and

therefore declares that a microburst has been detected.

This result is indicated in Fig. 9, showing the overlap

of the surface divergence and middle-altitude rotation

features.

This example illustrates the ability of the system to

combine evidence from multiple sources. In this case,

a surface divergence signature was recognized from

both velocity couplet and radial shear signatures. The

resulting combined surface divergence signature is of

higher reliability than either signature individually. The

capability of the system to merge these signatures increases the robustness and reliability of the microburst

recognition process.

Figure 10 summarizes the results of processing seven

volume scans of JAWS data for 14 July 1982 lasting

fourteen min from 143I to 1445 MDT. Two microburstswere detectedduringthisinterval,thefirstduring

1431-1434 and the second during.1442-1445. Each

microburstwas nr.ognizedfor two volume scans,as

indicatedby the cen{roidsplottedin the flgu_.

The microburst ruleset has been run on a set of 25

Denver microburst cases covering 77 volume scans of

radar data. Quantitative evaluation of these results is

currently in progress.

b. Gust front recognition

A gust front is the leading edge of a cool air mass

that has recently descended from a thunderstorm or

convective cloud (National Academy of Sciences,

RECOGNtZIO _JRFACE MICROBURST

• j RADAR

MIDD.LE- ALTITUDE

ROTATION

41R_RT $_FACE

DIVER_E

FIG. 9. Recognized surface microburst.

454

RfCOGNIZEO JAW8 kNCROilURSTS, I4 JiA. I_

RAOAR

/

,as I_¢O 1_4lZJ;O

O1[ NV4[ Pl _ 414[(:OGNIZI[O

AOIPOIIT ""'-d'_ _ l  ̧_ 4T 1441_ MOT

IGAg|: *--_-'---I I(N( M.

FIG. 10. Recogn_d JAWS microburm.

ORIGINAL P,a,JE"_ IS

O]_ _K)R QUALITY
MArcH I_)B7 STEVEN D. CAMPBELL AND STEPHEN H. OLSON 15

10 Km

6 Km

HOmlZONTAL SCALE

FIG. 11. Aircraft encounter with a gust front.

1983). This air mass spreads out at the surface and is

often found many kilometers away from the parent

storm, as shown in Fig. II. Although gust fronts pose

less of a threat to aircraft than microbursts, an ah-craft

passing through one can experience turbulence and

buffeting. .Also, the ability to detect gust fronts is useful

in predicting wind shifts that cause active runway

changes (McCarthy and Wilson, 1985).

As shown in Fig. 12, a gust front is characterized by

a region of cold air outflow converging with a warm

air inflow. This convergence creates a long, thin line

of negative radial shear (decrease in radial velocity with

increasing radial distance), independent of whether the

gust front is moving towards or away from the radar.

The gust front rulesct initially looks for shear regions

that have a high probability of representing a gust front.

These regions are declared to be high confidence features on the basis of such evidence as proper shape and

size and high correlation with shear regions in adjacent

tilts. These high confidence features are then used as

islands of reliability to guide the processing of regions

with weaker evidential support.

An example of this process is illustrated schematically in Fig. 13. In tilt 1, the line of shear is long and

unbroken, and thus it is labeled as a high confidence

shear region. In tilt 2, however, the line ofshear is sprit

into two regions due to noise, missing data, or imperfect

feature extraction. The resulting segments are therefore

assigned as candidate or lower confidence regions. But

because these two segments overlap a high confidence

cot.o _m OUT_OW _ V_ Ae _:t.OW ..----

CC_NVER_ENC_

REGION

RADIAL ÷

SHEAR

FIG. 12. Gust front convergence _ignatures.

455
10 l()[ RN.\L OI \IM(JSPItERI( AND OCEANIC [ECIINOLOG'_ VOLUME4

111!

11112

Tm2

sft_

ree x trsct_

/ -I  ̧ "_

i"

High C,_m_mc4

f k Reem

._/ _f_eet Re_ms

W

S'vw _Qmn

FIG. 13. Use ofevidentJaJ support to guide gust front processing.

region on an adjacent tilt, the expert.system directs the

radar image processing element to grow (enlarge), the

two regions and examine them again. In this case, the

two regions now touch and are merged into a tingle

region which can now be assigned high confidence.

When one or more shear features in a tilt are recognized as representing a gust front, WX 1 assembles

them together into a convergent line signature. This

convergent line signature can be combined with other

recognized features, such as a refleetivity thin line, to

form a gust front signature. If shear line signatures in

adjacent flits overlap sufficiently, they are assembled

to form a gust front signature for that volume scan.

Gust front signatures from successive volume scans

can in turn be combined to yield the recognition of a

gust front over a time sequence of radar observations.

To illustrate this process, consider the radar data of

Fig. 14. These data were gathered by the National Severe Storms Laboratory (NSSL) at Norman, Oklahoma

and contain a large convective storm moving eastward.

The dataset includes four volume scans covering a 15

vain period, plus one additional volume scan 52 rain

later. The figure shows the surface elevation scan for

the first volume. A squall line is seen in the reflectivity

field (upper panel) and a line of convergence is seen in

the velocity field (lower panel). The scale is 1 km per

pixel for these 256 by 256 pixel images.

Figure 15 shows the gust front features detected by

the system for the first four volume scans. Note in particular that the gust front feature for volume 2 is broken

into two distinct parts. Nonetheless, the ruleset recognizes these two segments as representing a single gust

front shear line. Furthermore, it is able to recogni_.

that these features recognized in successive volume

scans represent a single gust front moving westward.

Figure 16 shows ability of the system to predict the

location of the gust front line. The gust front features

for the first four volume scans are plotted at the left

side of the figure, with a rectangle indicating the cenFIG. 15. Gust front signatures, 2145-2200 CST.

456 Ok/GI"1AL D......

OJ_ ]_OOR QU'-,-.,._,ITy
MARCH 1987 S FEVEN D. CAMPBELL AND STEPttEN It.

0RIG_rNAL PAGE IS

D_ POOR QUALITY,

OLSON 17

2146 -2200 CST 2262 CST

x--,

AGTUAL

8¢,AL,E I I

eO Kin.

r

FIG, 16. Gust front tracking and prediction.

troid of each feature and a line indicating its orientation

•and approximate length. At the right side of the figure

are the predicted location of the gust front 52 min later

and the actual location of the gust front at that time

as determined by the system.

7. Snmnmry

This p: per has presented work on the development

of an artificial intelligence-based system for recognizing

low-altitude wind shear hazards from Doppler radar

data. The approach employed by the WX 1 system is

to use expert system and computer vision techniques

to emulate the symbolic reasoning and visual proce_

ing capabilities of a radar meteorologist. A rule-based

expert system employs heuristic rules to capture meteorological knowledge, and reasons symbolically about

radar image features represented as facts in its working

memory. The expert system invokes numerical and

image processingoperations on features by sending

messagestoWX l'sradarimageprocessingcomponent.

The basicmode ofoperationintheWX I systemis

tobuildup an interpretation oftheradardataby performingsuccessivestagesofabstract/on.The inputradardataareconvertedtoa setofregionsby an initial

featureextracti,,n step.These productlevelfeatures

arecombined toform more abstractfeatures,leading

ultimatelyto therecognitionofwind shearhazards.

This process is directed by a setof recognition rules

which express expert knowledge about radar meteorology, including weather phenomena and radar data

artifacts. This knowledge includes structural models

linking weather phenomena to radar image features.

The systemdesignincludes a means for inexact reasoning about features using confidence factors. Confidence factorsare usedto accumulate evidence and to

resolve multiple competing hypotheses. The use of CFs

allows the system to constrain the search for wind shear

signatures to a set of likely candidates. It also allows

the system to process these features in an adaptive

fashion using past history and contextual cues.

Rulesets are currently being refined for recognizing

microbmst and gustfront wind shearhazards.The i,,/-

tial results presented demonstrate the ability of the system to recognize these hazards. Work in progress includes a quantitative assessment of the system performance, including probability of detection and false

alarm rate.

Acknowledgements. The authors wish to thank Dr.

John McCarthy and the Research Applications Program (RAP) staff at the National Center for Atmospheric Research (NCAR), and Dr. Dusan Zrni6 of the

National SevereStorms Laboratory (NSSL) for their

assistance in supplying Doppler radar data and meteorological expertise. The National Center for Atmospheric Research is supported by the National Science

Foundation, and the work at NSSL was funded in part

by the Federal Aviation Administration. We also wish

to thank Dr. James Evans and staff of the Terminal

Doppler Weather Program (TDWR) program at M.I.T.

Lincoln Laboratory for their assistance in supplying

Doppler radar data, meteorological expertise and computer processing support.

REFERENCES

Allen, E. M., 1982: YAPS: Yet Another Production System. TR1146, Maryland Artificial Intelligence Group, Department of "

Computer Science, University of Maryland, 13 pp. [Available

from the University of Maryland].

Buchanan, B. G., and E. H. Shortliffe, Eds., 1984: Rule-based Expert

Systems, The MYCIN Experiments of the Stanford Heuristic

Programming Project, Addison-Wesley, 748 pp.

457
l_ J()ITRNAI. OF ._TMOSPHERIC a, ND OCEANIC TECHNOLOGY VOLUME4

[:¢dcra[ \_Latiorl \dmlnlstratlor_. log4: Ii:,;t:_m H'calhcr System

P/,m. [ .S. Go_ernmem Priming Olticc, \V_hinghm. D.C.. 23,_

PpFujila, T. T., 1985: The Downburst: Mwvoburst and Macroburst.

SMRP Research Paper Number 210, University of Chicago,

122 PP, [NTIS PB-148880 !.

Fujita, T. T., 1986: DFW M_-robur_ on August 2. 1985. SMRP

Research Paix'r Number 217, Univer_ty of Chica6o, 154 pp.

[NTIS PB 86-131638].

l-lay_-Rotlx, F., D. A. Waterman and D. B. Leuat, Edx, 1983: Build-

. i_ F.3ox-n Systems. Addimn-Weaey, 444 pp.

McCarthy, J., and J. Wilton, 1985: The Clasmfy, Locate and Avoid

Wind Shear (CLAWS) Project at Denver's Stapleton International Airport 01z_v_on_ Tenting of Terminal Weather Hazard

Warnings with an Emphasis on Microbum Wind Shear. Preprints. Second International Conference on the,4viation Weather

System, 247-256.

National \cadem3 of.Sciences. Committee on Low-Mtitude Wind

Shear and Its Hazard to _iation. 1983: Low-.llttlude llTnd

Shear and Its Hazard to Aviation. National Academy Press,

Washington, D.C., 112 pp.

Stevenson, L E, 1984: ThnndenWrm Imlmct on Dearer Air Traffic

ConUol Operatiom and the Rote of NEXRAD. DOT-TSC,

RSPA-84-1, T_n Systemz Ceater, Qtmbridlle, MA,

[NTIS PB 84-189729].

Weinreb, D_ D. Moon and R. Sudlman, 19113: _ Mac_te Manual

Artificial Intellilen_ Laboratory, _metta lastitute of

Technology, Fhqh Edition, 692 PP. [Available from tim Mmmchmmtt Institute of Technology].

Wilton, J. W., IL Robert& C. Kettinller and J. McCarthy, 1984:

Microburst wind structure and evaluation of DoplMer radar for

airlift wind shear detection, Y. ClimateAppi. Meteor., 23, 898-

915.

OF :_'OOR QU_%LIqlZ

458
To apP_: in -Digits1 ZuVe PL'oce!s_ '

'and "Vl:mmZ Cmmmnlcetions TechJtol_lLea i

In 14eteofolOgy'. 26-29 Octobelc Iglli?,,

llylltl: lle41ehcy XoCel. cmsblrlqde. Ilia

Automated Detection of Microburst Windshear for Terminal Doppler Weather Radar"

Mark W. Merritt

Lincoln Laboratory, Massachusetts Institute of Technology

P.O. Box 73, Lexington, MA 02173-0073

ABSTRACT

An image analysis method is presented for use in detecting strong windshear events, called microbursts, in

Doppler weather radar images. This technique has been developed for use in a completely automated surveillance system being procured by the Federal Aviation Administration (FAA) for the protection of airport

terminal areas. The detection system must distill the rapidly evolving radar imagery into brief textual warning

messages in real time, with high reliability.

1. INTRODUCTION

The term "microburst" refers to. the divergent windshear formed when a strong downdraft impacts the

Earth's surface. Such downdrafts often occur within convective storms, and are also found in virga shafts

where no rain reaches the ground. This form of low-altitude windshear has come into focus in the last decade

as a serious hazard to aviation, and has been blamed for several major aircraft accidents. The FAA is currently procuring a capable Terminal Doppler Weather Radar (TDWR) system, to be placed near major sirports for the detection of these windshear hazards.

The problem of detecting microburst windshear events using surface-based Doppler radar is addressed ia

this paper. The characteristics of the phenomena to be detected, and of the sensor to be used, differentiate

this problem from more classical computer vision and image processing applications. The lack of man-made

edges and the amorphous time-varying shape and size of the windshear regions render most well-known edge

detection and object tracking techniques ineffective. To overcome these difficulties, an ad hoc scale-independent shear detection method is used to locate the hazard regions, which are then tracked as distributed

events, not individual point targets.

The subsequent sections of this paper discuss the Doppler radar signature of microburst events, the details

of the detection procedure being used to identify these signatures, and the performance results obtained to

date.

_.

2. MICROBURSTS AND THEIR SIGNATURE IN DOPPLER RADAR DATA

The physical phenomena related to a microburst are depicted in Figure 1. The strong downdraft which

creates the surface divergence defining the microburst will often exhibit convergence and rotation at middle

and upper altitudes. This downdraft is also typically associated with a storm cell, which is observed as a region

of locally strong reflectivity [1}.

, _ nlf_.lCTl_ III_IJlUItA

I '

't.... .o,EfULCTIVIV'Y ......oo..

_ 04vI IG|NC f

_6d_l _OI_IV

Figure I Radar signatures associated with

microburst-related phenomena.

I

I

-j

FigUre 2: Schematic diagram of an aircraft encounter

with a microburst outflow.

Ihe work descrfbed here was sponsored by the |:ederal Avialton Adminislrarton lh(.

Untied States Government assumes no liability for its contents or use thereoi"

459
u46 i0

The surface divergence formed by the downdraft is the primary characteristic of the microburst, and the

strength of this outflow determines the degree of hazard which the microburst presents to penetrating aircraft.

As shown in Figure 2, as an aircraft encounters a microburst when landing, the outflow is first manifest as an

increase in headwind which lifts the aircraft above the desired glide slope path. As the aircraft passes through

the outflow center, the strong downdraft and sudden tailwind dramatically reduce the lift force of the craft,

causing it to lose altitude rapidly. If the aircraft has inadequate reserve thrust to :ompensate for this loss of

lift, ground impact may result short of the runway.

Since the surface divergence is the primary feature of the microburst, and the actual source of the hazard

to aircraft, the focus in this paper shall be on the detection of this divergence region, independent of the

remaining radar observables shown in Figure 1. While this approach was initially chosen to minimize the

computation requirements and complexity of the detection process, the resulting algorithm has also been

shown to perform quite well. Work on a more advanced detection process, utilizing the additional microburst

features aloft, is presented in [2].

The primary quantities measured by Doppler weather radar are reflectivity and (radial) velocity. The

reflectivity measurement is related to the number and size of the radar scatterers (particularly raindrops) in

the radar sample volume (typically 1 degree in azimuth and 120 meters in range). The velocity measurement

indicates the mean of the radial component of the scatterer velocities. The images of these quantities (which

are sampled on a polar, not Cartesihn, grid) provide the basic precipitation and windfield information used by

radar meteorologists to locate and characterize storm cells, and related windshear hazards.

The color images shown in Figure 3 illustrate the radar reflectivity and radial velocity images for each of

two typical microbursts. The first case (Figure 3a) is from data collected on 1 July 1986 using the FL2

Doppler radar in Huntsville, AL. An angular wedge of data was collected to the North of the radar (located at

the vertex of the wedge), where air-mass thunderstorms and showers were present. Several strong reflectivity

ceils are present, and are producing divergent outflows of varying strengths, The two regions outlined in red

are the output of the microburst outflow detection algorithm. The leftmost region is a microburst at the peak

of its outflow strength, while the smaller outflow to the right is a microburst which is just impacting the

ground; the strength of the outflow for this microburst will increase with time. The second case (Figure 3b) is

taken from 25 July 1986, and shows a strong isolated storm cell producing a clear microburst divergence

signature, located roughly 20 krn southeast of the radar. These examples indicate the amorphous nature of the

microburst surface images, and the variation in size, strength, and shape typical of these features.

Figure 4 shows the range-velocity profile for the outflow from Figure 3a, for each of four adjacent radials

from the radar. Each plot shows the radial velocity as a function of range, and the line segments above each

plot denote the segment of the radial where the detection algorithm found divergent shear. These plots illustrate the general character of the shear signature, and its variability from-'radial to radial. On the two center

AZ • 3173

Bi '

°i

0

ol I ! J- :

._---_: -J- i -_- .... ;....

AZ- 3t_-3

" 3143

4 _ b 7

Range from radar (km)

Figure 4: Range-velocity profiles for 1

July 1'986 case. Each plot shows the

radial velocity as a function of range from

the radar, for four adjacent radials of the

radar. The line segments above each plot

indicate the divergent shear segments

identified by the microburst detection

algorithm.

ORIGINAL PAGE I$

.O!_ P.OOR QUALITY

460

w
• . * i*" "* It

_.,;--T O

"'I

i:

,e

i,

Iteflectlvlty Velocity

(4J. Ii;;¢"7_ ;_ -., - -- --... - ----,

' .... I

I_, _'...,,,_4e, jJ..:w-- .... ! _: ::::.":'£ _. ._.._._:,j

5 I0 15 20,25 30 35 40 4,5 50 55 _ 6_ -12-10 -8 -6 -4 -2 0 2 4 6 ' lO 12

:i_, Case fn)m _, July l O_. al _():l _41 I. Radm is h,cated 20 km n(_rthea,,t _d" n_icrc_bur,;t

F_gure 3: Radar images for typ't_-a] mncrobursts. Images on left_,re radarretlectr, q:x. _n t,n,ts ofdBz (3,_ !t-;/

_s light ram, 50 dBz is extremelv"_'avv ram or ha_l_ Images on ri_:ht are radmlv,:h_citv. _n units ,)f :': -

where negative velocities _ndicate moti_m :_)v.,ards the :adar t-_ach ima,.:e depicts :u: area 26 km.sq',,are i"!:..

reg]tm,, ,m.:]incd in red are IlliCI(It3III:_{ al,.L',_rithm ala;!n._, wl!erc .,'.',,::;.: di'.¢rgcn: -!:'.'at !!a'.c I_ec;_ d,:" ....

B,_t!', ca.-,cs v,,q,.. _fi_ser,.'¢d wnh :h,. 1:1.2 :adar. _h_i,' :, a.p, !,,:a::-d ::: ituntxv,t!c -\1.

461
mdia_ (azimuth angle_ 315.3 and 316.3), a single point anomaly is seen at roughly 5.3 km range. At this

range, the velocity measurement has been biased by the power returned from a localized clutter source (i.e.,

birds, aircraft, buildings, etc), and has disturbed the smooth shear pattern. As explained below, the shear

detection process incorporates specific tests to avoid being distracted by such localized disturbances.

3. Algorithm Description

The microburst surface outflow detection algorithm is composed of three basic stages, illustrated in Figure

5. The first stage attempts to locate regions of divergent shear along individual radials of velocity measuremerits (as shown in Figure 4), resulting in linear segments of detected shear. The second stage associates these

segments in azimuth, joining together overlapping segments found on adjacent radials. The result of the second stage is a set of two-dimensional regions of shear. These regions are then correlated from radar scan to

scan in the third stage, to produce time histories for each region. Shear regions which exhibit adequate time

continuity and sufficient outflow strength are then declared as microbursts.

VELOCITY IOENTtF|CATION ASSOCtATION CORRELATION I - DETECTIONS

Figure 5: Microburst outflow detection algorithm block diagram

Shear Segment Detection

The divergent shear segment detection process is the fundamental element in the algorithm; the remaining

stages serve primarily to filter out those segments and regions which are not of adequate significance to generate microburst alarms. The job of the shear segment detector is to identify the characteristic divergence patterns, such as those in Figure 4. The most straightforward approach to detecting this pattern would be the use

of a local linear operator such as the one-dimensional gradient: Lx = f(x+n) -f(x-n), tb.e output of which

would be thresholded against a specific gradient level. This approach would then detect segments with consistent shear above the threshold level.

The simple gradient operator has several well-known difficulties, particularly its sensitivity to noise and

spurious data values. The use of smoothing and outlier rejection pre-filters may be used to reduce the noise

level, at the cost of some blurring of the gradient information in the data. Another difficulty with this approach is the implicit spatial scale involved in choosing the parameter 'n', which must be chosen to match the

scale of the shear. Since microburst outflows are typically small (< 1 km diameter) when they first impact the

surface, and grow to much larger diameters as they intensify, no single scale will be optimal over the full

duration of the microburst lifetime. Multi-scale techniques could potentially be used to overcome such problems, by merging the outputs of several gradient operators of different scales applied to the signal.

In an effort to avoid the complication associated with scale-specific gradient operators, a scale-independent technique has been employed for the shear segment detection. This method was adapted from the pattern

search algorithm developed by Zrnic and Gal-Chen [3] for the detection of divergence at storm tops. The

resulting shear identification method is tailored to find runs of velocity measurements which are 'generally

increasing' with range, and includes several specific conditions designed to cope with data anomalies typical

of weather radar observations.

The shear segment detection process, detailed in Figure 6. consists of sliding a window along a radial of

velocity.' measurements, applying a detailed set of segment start/stop tests to locate sections corresponding to

significant divergent shear. The criteria used to determine whether to start or stop a segment at the current

sample point are both based on the notion of a 'window' of sample points (typically a span of 4 samp!e points.

or 0.48 km actual distance) ahead of the current sample point. The basic detection process proceeds as shown

in Figure tJ(a), by sliding the window out in range until the start-of-segment criteria (START-GOOD and

START-SMOOTH, as described in Figure 609)) are satisfied. At this point, a new segment is started, and the

window is advanced in search of the end of the segment.

To expedite the search for the end of the segment, and to reduce the chance of ending the segment prematurely, not all sample points are considered in this search. After the starting point has been located, subsequent sample points are chosen for consideration based on the NEXT-GATE rule, which attempts to move

from point to point in a consistently increasing trend, but avoids getting 'caught' on large 'spikes' in the data.

At each subsequent point chosen by tills rule, tile sample points in the window following it are tested for Q_e

1

i,

"It

462 _>!-,tGtNAL PAGE I8

OF POOR QUALIT_
1 0

t

end,of-segment criteria (TERM-BAD or TERM-JUMP), which end the segment when either a decreasing

trend or an unrealistically large increase is found.

Once the end of a segment has been detected, the ending point of the segment is adjusted so that it lies at a

local maxima. This adjustment is accomplished by incrementally moving the ending point back (towards the

starting point) one sample point at a time until the MAX-RULE criteria is satisfied. At this point a segment

has been found, and the endpoints both correspond to local extrema. An additional set of tests are now

applied, to determine if the segment thus located exhibits the basic characteristics of a 'generally increasing'

run of values. Each of the three validation tests (IN-RANGE, CONSISTENT-SLOPE, and DISTRIBUTED-SLOPE) must be satisfied by the segment for it to be considered for subsequent processing.

Azimuthal A.uociation

The second stage in the outflow detection process is the association of the shear segments in azimuth. The

goal of this step is to merge the shear segments from the previous step into 'clusters' of adjacent segments.

This merging is accomplished by considering each pair of segments found on a radar scan, and tagging them

as belonging to the same cluster if they overlap in range and lie on adjacent, or next-to-adjacent, radials of

the radar (typically spaced 1 degree apart in azimuth). The sets of segments connected by this single-linkage

clustering scheme are then denoted as two-dimensional shear regions. Several characteristics are computed

_1

3

I-o.. I

noxt Gato

0¢

TERM-JUMP

MAX-RULE

and

and

?

$4ve oeQrnent Doiot o

T V

(a)

Figure 6: Flowchart (a) and test criteria

microburst outflow detectitm algorithm

[ START-GOOD ]

None of the sample points in the window are either

i) "bad" (i.e., a valid velocity measurement was not possible

because of Low signal power) or,

ii) have a velocity less than that at point X

[START-SMOOTH]

The velocity values at points X, X+I. and X+2 are monotonicarlly

increasing.

[NEXT-RULE]

From a given sample point X. choose as the next sample point

that point Y such that the difference between the velocity

measurement at Y and at X is both non-negadve and less than

50% greater than the minimum non-negative difference to all

points in the window

[TERM-BAD]

More than 314 of the of the sample points in the window are

either

i) 'bad' (i.e.. a valid velocity measurement was not possible

because of low signal power) or.

ii) have a velocity less than that at point X

/TERM-JUMP]

The difference between the velocity at the current sample point

and that point in the _ndow with the smallest velocity value

greater than that at the current point exceeds 1.5 m/s.

[ MAX-RULE]

The velocity value at the current sample point is greater than or

equal to the value at the previous sample point (toward the

starting point), or both values are "bad" measurements.

(IN-RANGE]

No more than 1/8 of the sample points in the segment may have

a velocity value which is either less than the velocity value at the

_rting point of the segment or greater than that at the ending

point

[CONSISTENT-SLOPE]

The r_nning mean of the velocny v:dues, calculated over

consecutive sample points, must be monotomcally increasing over

the em length of the segment

[DISTR/B UTF ,.3-.SLOPE]

The ratio of velocity differences: (velocity(Y)-velocity(X)} I

(velocity(Y-l)-velocity(X+l)}, where sample points X and Y are

the starting and ending points of the segment, respectively, must

be at least 0.6.

Co)

(b) for divergent shear segment identifi'=ation stage of the

463 OklGINAL PAGE IS

OF POOR QUALITY
t z+b 10

for each region, including the number of segments, total area, and the maximum velocity difference across

any shear segment in the region. These characteristics are used by the third stage to judge the significance of

the shear feature for alarm generation.

Time Correlation

The final stage of the algorithm processing attempts to associate the two-dimensional shear regions in

time, across successive scans of the radar. The algorithm compares each cluster found on the current scan with

all those found on recent previous surface scans (where 'recent' means the lesser of: two scans, or two minutes, in the past). Each previous cluster is then tested for spatial overlap with the current cluster. In the usual

case, where all the previous clusters which overlap the current cluster belong to a single existin I microburst,

the current cluster is tagged as also belonging to that microburst. If the overlapping clusters belong to muldple

microbursts (i.e., microbursts which are closely spaced together), the current cluster is tallied as belonging to

the microburst for the previous cluster which 'best' overlaps the current cluster. If the best overlapping previous cluster is not already tagged as part of a microburst, and the current cluster passes the size and strength

thresholds, then a new microburst is declared.

By performing such an association, it is possible to identify situations where a previously-detected single

microburst is now detected as two separate clusters (e.g., because the shear detection step may have missed

some actual shear segments). In such cases, these clusters are merged together, to provide a more consistent

output product. A second benefit is the ability to filter out those detected shear regions which do not persist in

time. Observation of the performance of the shear detection and clustering stages have indicated that most

false alarms are not persistent, while actual microburst hazards are typically observed on several consecutive

scans. By requiring multiple detections of a shear region before declaring an alarm, the false alarm rate is

reduced considerably. This time filtering rarely causes actual microbursts to be missed, since shear regions

below the microburst intensity threshold are usually observed prior to the outflow reaching an operationally

significant strength.

4. Performance Assessment

The performance of the microburst outflow detection algorithm has been evaluated through an extensive

data collection and analysis program. This program was designed to compare the microburst alarms generated

by the algorithm when appiied to actual weather radar data with the detailed analysis of those cases performed

by experienced radar meteorologists.

The role of the human analyst is to examine the raw radar measurements, in an offline (not real-time)

environment, searching for microbursts. The location, extent, and strength of all identified microbursts are

then documented for each surface scan of the radar (roughly once per minute). This database of microburst

'ground truth' may then be compared to the algorithm alarm output to determine detections, misses, and false

alarms. This manual analysis is an extremely time consuming task, and the evaluation described below is the

result of several man-years of combined effort from scientists at Lincoln Laboratory and from the National

Center for Atmospheric Research (NCAR).

To achieve uniformity in the ground truth database, which involved efforts from numerous analysts in the

program, a commonly agreed definition of a microburst was needed. For the development and evaluation of

the detection algorithm, a microburst is defined as a divergent outflow region which eLxhibits a wind speed

difference of at least 10 m/s over a distance of no more than 4 kin. Note that the velocity difference may

extend beyond the 4 km scale, so long as the required 10 m/s difference exists within some 4 km sub-region.

A microburst is considered 'ended' when the velocity difference (over a 4 km scale) drops (and remains)

below i0 m/s for a period of at least two minutes.

Rules for scoring against ground truth

To evaluate the performance of the algorithm, two basic quantities are desired: the Probability of Detec.

don (POD) and the Probability of False Alarm (PFA). The POD is defined as the ratio of the number of

events detected by the algorithm to the total number of events. The PFA is the ratio of the number of false

alarms to the total number of alarms.

These definitions relate performance to three fundamental concepts: an event, a dettction, and a false

alarm. In this application, an event is defined as a single observation of an actual microburst by the radar, on a

low-elevation angle scan. Each actual microbt|rst is typically observed on several sequential scans, and hence

464
_ I_'GOR _UALITy

846 I0

represents several events. Only those actual microbursts which fail within 30 km of the radar are considered in

the scoring. An event is considered detected by the algorithm if the rectangle representing the event intersects

any rectangle(s) representing a microburst alarm from the algorithm. A microburst alarm from the algorithm

is considered a false alarm if it does not intersect any rectangle(s) representing actual microburst events. To

provide an operationally realistic evaluation of the algorithm, certain alarms which would be strictly classified

as 'false alarms' are tallied separately. Declarations which overlap actual events which appear on radar scans

within two minutes (before or after the current scan) are not considered false alarms, nor are any declarations

which appear in the immediate vicinity (within 2 km) of actual microbursts considered false alarms. Also

excluded are algorithm declarations which can be clearly traced to defects in the data acquisition system (e.g.,

ground clutter residue), which are not representative of the specified TDWR radar platform.

Data cases used in the evaluation

The performance statistics presented below are based on the radar measurements made on the dates shown

in Figure 7, using the FL2 Doppler weather radar [4]. During the data collection period from which these

cases were selected, the FL2 radar was located in Huntsville, AL as part of the FLOWS '86 and COHMEX

data collection programs [5]. It is important to note that all of the microburst events used in this performance

evaluation were associated with strong precipitation (as were virtually all of those microbursts observed during

the Huntsville data collection program). No 'dry' or 'virga' microbursts (those which have little or no precipitation reaching the ground) were available for this evaluation. The 1987 FLOWS data collection program is

currently in progress in the Denver, CO area, where data on a better mix of both dry and wet microbursts are

being collected. The performance analysis results for the Denver microburst collection are not yet available.

Date Microbursts Surfacescans Time period (hrs)

June 7 5 40 1.7'

July1 7 75 2.2

July25 12 67 3.8

July31 6 144 2.2

Sel3t26 8 100 3.7

Totals: 38 426 13.6

4

Figure 7: Cases used for performance evaluation. All cases taken

from 1986 data colected with FL2 radar, in Huntsville, AL

Performance statistics

For each of the days listed in Figure 7, the outflow algorithm outputs were compared to the ground truth

information, and both detection and false alarms were tallied on each surface radar scan. The resuhs of this

comparison are shown in Figure 8, broken down into several outflow strength categories. Although the minimum outflow strength required for a microburst has been set at 10 m/s, a category for shears below 10 m/s is

present in the chart. This category is needed for those events which temporarily drop below the 10 m/s threshold (for at most 2 minutes) before intensifying, and are hence accepted by the definition as a single continuous microburst.

IAIIO O_ 8COIq_ PtNFOA*IIO II UAT flIT

+!I °-r ° O1111¢11O41141

¢ Iol/. ii+ 14 roll ll.l|m/l II.14 m/I II • Ill

l_IOI II;_¢lcUm,n| 1141'1+ IIII_ III'IL IllS+ I14_

P_Ol 1+ b +¥< ]01+4111 tl2/lli "

PIIOI il[_ lq_ +V );IN)m/I| 7ifPI

l,'llOll ll_l,k.l I,+,+_ l 14s_3 •

?Qtb

tPIL

4_

Figure 8: Microburst detection algorithm performance statistics

465
The figure clearly indicates that the detection performance improves with the strength of the outflow, and

that strong outflows (above 20 m/s velocity change) are almost always detected. The weaker shears are detected with lower probability, due in part to the fact that the algorithm often underestimates the true strength

of the outflow, so dmt weak events fall beneath the detection threshold of 10 m/s.

Note that the statistics presented in Figure 8 indicate how well microbursts were detected on a scan-byscan basis, and not on an event-by-event basis. The outflow detection algorithm rarely misses a microbur_t

over its entire lifetime; of the 38 microbursts used for the statistics presented here, only 3 were entirely missed

by the algorithm (92% detection rate). These events were very weak (averaging velocity difference of 13 m/s)

and lasted for only a few minutes each.

S. Future Work

The development and operational evaluation of microburst detection techniques is a major component of

both the Weather Radar program at Lincoln Laboratory, and the Research Applications Program at NCAR.

Considerable work remains to be done before the algorithm performance is adequately tuned and evaluated.

The primary goals for near-term improvements to the microburst detection algorithm include:

1) a complete examination of the algorithm performance against a larger set of single-Doppler ground

truth cases, plus more detailed case studies using dual-Doppler and surface wind station measurements,

2) the application of a clutter residue editing map prior to the detection algorithm processing, to determine the ability of such a map to reduce the algorithm false alarms from clutter-biased measurements,

3) several enhancements to the outflow detection process to reduce the number of false detections, to

better measure the wind speed change through the outflow, and to improve the time continuity of the

algorithm output [to provide a product more comprehensible to the end-user].

Additional research into microburst forcing mechanisms and precursors, as well as aircraft response to

microburst wind shears, will surely result in an ongoing cycle of development and refinement of the automated detection techniques, to keep pace with meteorological understanding of the microburst phenomena.

6. Acknowledgments

The work descrit_ed in this paper is the result of the cumulative effort of numerous people over the last

several years. In particular, the 1986 microburst ground truth analysis performed by: Mark Isaminger, Charles

Curtiss, and Nat Fischer, from Lincoln Laboratory, and Cathy Kessinger and Rita Roberts of NCAR, was

vital to the algorithm development and evaluation reported here.

7. References

[1] R.D." Roberts and J.W. Wilson (1986), "Nowcasting Microburst Events Using Single Doppler Radar

Data," Preprints, 23rd Conference on Radar Meterology, 22-26 Sept., 1986, Snowmass, CO, American

Meteorological Society.

{2] Campbell, Steven D., and S. Olson (1986): WX1 - An Expert System for Weather Radar Interpretation.

Coupling Symbolic and Numerical Computing in Expert Systems, J.S. Kowalik (ed). Elsevier Science Publishers B.V. (North-Holland).

[3] NEXRAD Program Office (1985): Divergence Detection Algorithm Description, NX-DR-03-042/10,

Next Generation Weather Radar Algorithm Report.

[4] Evans, James E., and D. Johnson (1984): The FAA Transportable Doppler Weather Radar. Preprints,

22nd Conference on Radar Meteorology. Zurich, Switzerland, American Meteorological Society, pp.

246-250.

[5] Dodge, J., J. Arnold, G. Wilson, J. Evans, and T. Fujita (1986): The Cooperative Huntsville Meteorological Experiment (COHMEX). Bull. Amer. Meteor. Sot., 67, 417-419.

466
P

12.

I. R,,p*rt lie. i 2. _ Aceewee h. I

A TC- 138

4. Titko _ Svl_ragl

.%ssvssmvnt ,_1" A_i{-9 V;,'=|hvr (]lannel Performance:

,'L..alysis and .%imulation

7. J_wlH

Mark E. Weber

S. _ 0,eeehNee I1_ _d Addrm

Lincoln I.ahoratory, MIT

P.O. Box 73

l,exington, _',4A 02173-0073

Slmm_iq ASemCVNNm ,_1 _ldrss=

Department of Transportation

Federal Aviation Administration

Systems Research and Development Service

Washington, DC 20591

TECHNICAL REPORT _I'ANOARO TITLE PAGE

3. _'o Cm_ No.

S. Roperl Ooto

31 July 1986

|. P_e_q Oq_ne= Cede

L balm,me of_,m,_m _ U,,.

A TC- i 38

o0. w,_ u_ me. (THUS)

t 1. CaNarNt W GroM 0040.

DT-FA01-80-Y- 10546

13 TyI_ ef AogmrtNd Pa_riodC4m¢od

Project Report

14. _ AOOmCyCmie

15. Sq_mu4unsrV Nms=

The wurk reported in this document was performSd at Lincoln Laboratory, a center for research operated

hy Massachusetts Institute of Technology, under Air Force Contract FI9628-85-C-0002.

1 |, AIMIWKI

ORIGINAL PAGE IS

OF POOR QUALIT]_

In this report, we use pencil-beam Doppler weather radar data, con_hined with on-airport ground

clutter r_xasuremcnts, to analyze the performance of the six-level weather channel in the next generation

airport surveillance radar, the ASR-9. A key tool was = computer procedure that used these data to

%imulatc the output of the ASR-9's weather channel, including effects of the radar's fan-shaped elevation

beams, short coherent processing intervals and ground clutter filters. Our initial analysis indicates that:

(a) the combination of high-pass Doppler filters and spatial/temporal smoothing should normally

prevent ground clutter from having a significant effect on the controllers' weather display; (b) the

spatial/temporal smoothing processor will result in weather contours that are statistically stable on a scanto-scan basis, reinforcing controller confidence in the validity of the data; (c) relative to the coarse

rcsuhation imposed by use of the NWS levels, accurate two-dimenslonal parameterizations of storm

reflcctivily can I)e estimated. Our assessment indicates that the ASR-9's weather reflectivity maps should

be rcliahle. The radar will he widely deployed at significant air terminals, and will provide a combination

of high update rate and large volumetric coverage not available from other sensors. These attributes

sho,hl lead to the ASR-9 becoming an important component of the Federal Aviation Agency's modernized

weather nowcasting .system.

ASR-9

weather channel

precipitation relief'rarity

fan-beam

I1. Key Nwds

airport survcillxucc radnr ground clutter

spatial and temporal smoothing

computer simulation

reflcctivity estimate accuracy

beamfillin g compensations

IS. Secw_ _ (el doi=fepe_)

Unclassified

zo. $_ _. (d d_o Ngol

Unclassified

II. I)induiu SIm=_=l

Document is 8vailahle to the public through

the National Technical Information Service,

Springfield. VA 22161 r.

FORM DOT F 1700.7 (8-69)

467
r

_C'' 5  ̧' :

-- ------ V-- --

:,:T--ZLq-'::'T' ].5: '_ T-;l{ _ LL 5P4] _!-#--'03 '' _01-Q'4

Prep.ml. 13th Cost/'erencl on Se,,'etr L,c'_rjl

3lotto•. 8alumore, FIbnalry 22-26, i9_,

_,mcrean Mile(tml0tlcil loctely

CHARACTERISTICS OF MICIIOIlIJIlTS OBSERVED iN THE CONTINEN'I"AL U.S."

ORIGINAL p_Og Tg

OF POOR QUALITY

Mirilyn M. Wolfson

Mimchu_tu I_Uiute ol Technology

Lincoln Laboratory

Lexington, MA 02173

, iN I RODUCTION

The topic of mKroburst_ m explored in this paper through a

hL';IOrH:il pers[_cti,al lid re_w OI the It',_dMI4 that haw t_en performed sln¢e FuIILa (1976) [irlI IntJrOduced the con¢ep(. Taken as I

,.hole. th_ body of work ictull]y defines m.:robu_u, arid beillll to

like son-.c O| the mluil S_ll_ Inward their undenKandin|. Hoover. a

mJmber ol dyr_m_cllly dml.'_l ph_rmm_na that. I_ve rise to su'oni

surface ou_/Iows ire _¢lng referred to as m_croburz_ The recent emphasis within the KH_ntiI_ iM i_letlon communitJ_| on undcr_ndinl

microbut_u makes II par_:ularly important to Cltelonze II'_$e vir_o_

phenomena i¢cord_ng to U_ mtttorologk:li n&iun_ lid _ •v_uon

hstard potemu|L Th_ paper cakes _Ome of [hi firSt stepS toward th_

eaiegorl¢iu0n, and emphasizes Idle of the differences in $lOrrru_ that

Cln be exlxculd in di[Ienlnl C|ln%luDk_lca| rtllmes.

2 HISTORICAL PERSPECTIVE

The w_rd "d0wnbunt" was Introduced by FuliU_ end BylrS

(19771 to destine the meteorological e'Rnf, which caused tim crash of

Elstern F]ilht 66 at JFK airport in New ¥ort¢ on 24 June 1971. in

whKh i Ihundenltorm downdral't btcame haMrdoui m _ operellon

0( let •lrcrifl (Fig. I). If I downdrl(I hal I sp_Id of it Itali ll ll#l It

_n ellitude of 300 [l Ii I (lompemba/ to Oli ol i _lll inlnipott Iolioi..

mg the lilull 3" |lideslOl_ on Sinai IplxOICh) and I Splllll lint Of

0 3 mi Or larger earl e enoulh to ha_ • noueelble effect on _ lip

craft (Fuj,li and Callceni. 1977)), then it qull_te_ is • dowflbun4-

la_er tt_ Icrm "m_crot_riC *as cresi*d to di_ingu_h _mall

_o_nbueicl (08 - i 0 kin) Irom llrller Oils (Fuliui, I9?ll. 19'79).

F_ / Sctllmatic dra_,inllof dn aii_r(il[tencou#utr wltk a micro-

_ursl Nol_ce rh_t the mcr¢_•d _e_lwind lifts _ll, plone a_iove rts

,n_e_ed lfidlSlopt ,,Aile die incelosed lailwtnd cou.les dle plane in

/oil below #Jr _n/end_d Ilid¢slope.

The inlroduetlon tO the rn_teoroloiJc&J commumty o_r the concept O( thl dolnlbulll met with IO_ coniroveRy and r._ll_¢e AS

t"upii (19_) notes, mOSt miteorolol,.u b<:lieved "thee i downdrtft,

n_ matter how l_on I it may be {Plide or _nclth _ cloud, ihollld

_eikin _o In insllnihclnl speed 101_ql balore rl_lchin I the lUdlCi."

Msny i¢itnlllli ilio wondered what Ilia difference was. _ any, bltwain ihl dowllbUrll Ind the waU known thund_tt4Qnnn do_ndrah.

Fuiili (1979) thoulhl they went el_endllly the Mrr_ but. following

¢l_ir preeedem in melaorology Ior eluiblishmg new ulrminololy for

extreme mcteorolo$i¢ll phanomena _al inl known to be danlemul.

ebose i _erm mote Iorciful than euen _ "dowhruih" introduced by

Fiwl_h and MliGIr (19141, i_ld defined it le.¢ol.din I to hJi po44nlial

h_lrd tO lirGfllS. Conlu3Lnn Itdl iK_I Ovllr what ex&cUy Ih_ ulrlm

deSCribeS: it will be made Chllr throulh the ee.rmw o( Ol_41rl_llon_l

studies in the next $e¢llOn thai s¢_lra| po._libly dynlm_ally ddu_¢t

_heno_rltni tin Qualify

_lpile rfllclion O[ the "dollmbutit'. Ihire /iS Irlal concern

it1 the t'_teOroIo|l¢il community illd elpetuilly it thai i_ailol_al levtre

• the work des¢flbed hirl will N#oruIOld by the Federal lvlultln

.adlmnllltllloft. The Unllfd Sims Goverfln_fll I_Jufn_s 11o

hi01hil for IU ¢omenr Or u_4 IberO(.

468

the National S¢_r_ Storms Laboratory (N$SL) with prevtnun i iir-

¢rilt IccdenU Iuch u the one mentioned ibove at JFK airport, Hiwe,_r. _t appeared to some scJer_lL_ that Ih_ very unnd Ih_ir rellted

lircr_t icc_denLI liiributed by Fuj{ta in downl:_lnit_ _re ictually

¢luled by iircralt penttrltion O( larllar Klhl |ultfronul. Plrl o( this

lrll.ll'_ent wal t>lll_l On deliNd du_l Ifld trip_l-_f fidir •l%il_'-

ses of IorlMIdl¢ iLorml in Ok_ahom_ m which no smlll still

do_ndrifu were found (Brlnd_l, 1977: lly, It?l). Th¢ eviden¢e

available to these relelrcharS sul$eited thit "lurllihtoline" dO_'n_uf_t

winds m;Ght will be tholl experienced lion i the leadlnl I edie of idv'anclt_ Iti_t ll_0nlJ. An lnemom_ter-bald wind Inlay detection illtern was deli£ned and insilled it airport3 (ti Low Le_tl Wind Shelf

Alan Sy_ulm (LLWAS): noel. 1980) bal_d on NS/L iicommindifinns. Ft_iita (1980. i981a) wt_4 to Imlli llnllihi m hli lirly lklpelt to

expliin _ difler_ncel btiwllen downbuniti aM lultlronu, esplclally

unth re|lrd to iha wind lhllr Mid they poled [Or ivglllfl. A len -

eral lk¢lxlcilm thai nothlnl n_w wU blin I d_umenuld _ImalMd.

Howiver. Pujl_ remained COnVinCed this ua_lualiy siron i,

sm_U tcakl downdrefU not only ellllled 1_ _ • ,_lr? reel Ihrellt to

ivuItlOn. He oblalnld iciendLl¢ lupllol_ lid fil¢tlllJel, inek_m I I

pk_r radars, tmu_mlnied liecrah, lid nna_lotmt muenl, fir I_eiect

NIMROD (Nord_rn llliemil Meummk)lieal Ibm_feh Im [Nl_,mbu_u_:

with lriv_iiv_) mill Chlealo in 197| (Pujl_, 1979), peoilct JAWS

(/net Airport Weather Smd_el; w_¢h McCardt# and Will.n) r_tr

Denver in 1982 (M_...4rO1y el ill., L9|2), end mo_ reccndy, l_)ecl

MIST (Mk_roburStx and Severe l"huMerltorml; with Wlkim_o) _lr

Huntsville in i956 (Dodle it ¢/.. 19g6).

Afar both NIMROD and JAWS. d_ doom wus r,de.

Iin_d to en¢ompa_ newly ot_r_ud phenomana. Aher NIMROD [he

downbuni wll rudelined is "in ouibum of d•mailn | winds on or

near thl ground" (Fuji'" and WikintoIo, 1981) where "dimiling

wll_ds" refereed to winds o( ii Ill 11 m/I; nuclbtitlU llrl limply

wind ivenU O! ihi rnalnii_Klt on I lmilltr I¢lil. Dllrin t l^Wl, ml_¥

mont microbunlti wi_ll found lid _ eli was II¢ordl_ly

shifted _ mltn0bucll wU Rdelined as havtnli a "d(fNremlil

pier v_lO¢lly lcr_il the dlverien¢e center gllller thin or equll in 10

_1 and Ihi lniihll diltance I_iwlen mixJmum lllg_olthin I and re,

cedln I centlll leM than 0¢ ©qlillll to 4 ira" (V/eli el el.. 19g41 "°

This definition now i_¢ompala_l weaker bul still hilhly divirllenl mitcorolollKll phlnomoni.

I minor impetui *is id(led In the ITlllOrOiO_l¢il invelillllion of mirobuJrs¢l when. liter _ ¢tuh o/PIll Afl_lrl¢ln World Altwayl Fli&ht ?Sg in July 19|1 stonily liter like-of| it .New Oileini

Intemiiionil Alrpo_1 ill which ill 149 plllOni on Mild It14_ I pePllOnl

on ihl ilround died (Fujlil° lill" Clricinl ¢¢ iL. 19131). I .IqlllOnil

Acidlmy of Sciet_:_l Committee tot lhe l_ldy O| Log-Allude Wind

Sh¢ir and ]iJi HliMrd t0 Aviluon will 10rmld under the lllonlIPlhq)

ol the _ederai Avllition Admlndtrilion (FAA). The linll relXirt o(

d'_lt committee (Nienil Re'.,¢ireh Coun¢tl, 1913) sUtel tl_l_ "Semi

,arid sheari hive been undeeiiood by metegmkllllu fOr I number ol

yeir_ These tN:hlde d_ |ound in lit (roll. _lrm and ¢c4d i_-

mill Ironu. [tic.i-." and ll_ll "molt [Of l] ire p¢edKUlbM.

IOrn_umei hours in ad_nlnce." They Io on io i IhiH "$¢ilmlsu

have recenily bellun to rll¢Ollniz$ the imporuin¢e o| storm tIoimdri|Ul

that ire unUSUally imall m honionlil crof4 ie¢lklnl aM thai Ire Of

sbon duration, Such dowr_drafu ha_ I_en celled n_rol_r_u " The

ml_orololicil ¢ommuruty finally _4emed ¢omaRced Ol' both the halaid OI low-ilutuKle wiM shear In il_lltion aM the eltfltence of

microt_es_ (iis_k_r, 1911).

The National Academy o/ Sciin¢_l Comm_tlee m_k se_lral

rt¢omm*ndatlonl, one OI which was {hit tha PAA "take Lmmedlale

iCtl0n IO develop II pulsed Doppler rid•¢ lyilem Ihal clh Ill ui_d tl_

oh,litre lllllher condi[_on_ il end around Illrl tetm_t_iis. "l'hn tarmur_l rldi¢ ly1_Im lho_Id _ ib_l tO operate wKh I hqlh dil_el (1[

"-_'_e $ignili_/l_.ll O( _ 4 km 19114 Ipparently Otlml_l$ {me ll:e

plinllul_y seal dinted by Fuilti (ltllb). _ linh'l liicum-

[crer_Ca ,, 40.000 km aM i¢ikl dilil_ arl m4de in _el_ Of i_o

order_ of ml|nllilde glen. il 400 kin. 4 kin, slid 0.04 kin.
B'_ : ,EFO, "ELE':E _ [E= -C'.O

r-,: T-20- ' -_,'?

; ].O-ZQ-,_'?, 3: IQF_ ;,_-T , :_.F-;-_ =_4[-_C--- -C.4,=_:-_._;_ _

15: l" T-HIT LL SPJ_-, _-61-6,0-__ ;=__0l-g4

PerprintS, 131h Cos_ereMce 04 Severe

•_torm$. Baltimore. Feb_ry 2_).26 '

Arr_rean MeteorolO_k:al Society.

CHARACTERI$'I"_C$ OF MICROEURSTS OBSERVED IN THE CONTINENTAL U.S °

L%£,

_e

Manlyn M, Wolfson

MatMchu._H4 |rdthute of TechnoloKy

Lin¢o|n Laboratory

Lexinlton, MA 02173 ORIGINAL PAGE IS

OF POOR QUALITY

, IN IREDUCTION

The topic of mv:robunltt uL expiated in t.hb, paper Ihrou{h •

hL_[orlcal perepecuve end rtv_w Of the StudMbs tl_s h_v_ L>een parformed striae Fuj{_ (19"76) firltInVOdt,K_d q.ho eOn_¢F Taken as a

*hokL th= body of wOrk act_ll|iy de_tne$ mk:robunlu, end beSU_l to

take Son'_ Of the mitml etepl fJowe,rd their undenmbnd|n|. Ho_r. a

number of dynamically d,_tm¢l phenomena Iha¢ Kn,_ ri:l_to stroP,[

surface outflow_ are bein= re/cn'ed to el mmctoburs_ The recent emphelms w_thm the Semenlil]¢ and eviit)on communities on underlulndJn I

microbur_ makes it parteubrly |mpoftant to cate|0r_:e these vanO_S

phenomena a¢cordin I to their meteoroloKk:e[ nature end I.ru4 avian

ha&ard pOtentul[. Th_ paper ulkes some of tl'_ first step_ towlrd thi_

ca[e$OruZauOn, and ¢mphasize._ tOme of the difference_ m stOrm= (.hat

cen be expected in different climatologtcal rqln_s.

_-. HISTORICAL PE RSPEC'TT VE

TI_ word "downburit" was |ntrodueed by _uiiu _,nd Byen

(197?) to describe the meUlorolo|iea| event wheh caused the c_=h of

Eastern Flight 66 at IF'K aupml in New York on 24 June 1975. In

wh_:h = thundenRo_ dew.laiR became I_._rdo_% m "d_ operation

of jet ah'craft (Fill I). If I downdrlfl Ms I ap_ed of at leal_ 12 [t/_ ag

an IJliIude of 300 ff, ill (¢omJ_lll'llbte to tJ_lt of a _41( lrePer|X)fl J'OIIOVeme the usual 3" Ihde$1ope on final al:q_roalah) and I Ip_llal e_nt of

0 5 mi or t, tier (large en¢._llh to have a not._eable effect on the aircraft (FujRa end CaPIcena. i977)), tMn It qua|_k_i aS e dowl_bu41_

L•mr d_ term "men01_Jn¢" w_s ¢reau_d m di_new_h Small

do_nbursu (0.8 - 4.0 kin) from [arler oriel (Fuji_, 1978. |979),

-

F_ I. I $ch*ma.c d,aw_ l of On •Jeer#at _nCO_Utr with a microbur_t Notice thor the i_Cre_Ued hw_lwind I_[ta th_ plon¢ a.!)ove its

,m¢¢ld_d Iti#lellop4 w_*ile e_e mCtt¢lXed tailwlad cou.se_rtht plane to

loll below, its _ntend_d &lidetlope,

The Inlrodu¢llon to the tt_teorololica[ community of d'_ concep¢of the do_nbu_t met with some conlroverly and r¢q;i=ul_;e.

FUl_U_ (195_) not¢e, m011 meleorololl_8 he|ilVed "th_t i do.dr&eL,

no matter how suon Itt _y be in.tide or beneath _ cloud, Should

weaken [o an insllmficam speed ionll before rqNIchin I the Sue|ace "

,Many lcient;U ,=110 _ondered what the difNmnee wlss, it any, be-

[wean the do_nbur_t and the waU known thum:len_Orm downdraf|,

Fulita (1979) thou&h_ they were eS_ent_l)y _e Mine but. followinll [he

¢l_ar pRcedent in meteOroloey (or es_bl_hit,_ _w _rminO_w for

extreme mereoro[oilcaJ phenomella [hal are known to be dint_emul.

chose a term mole forceful than even _ "dowflurt_h" _nuod_ed by

Fawbu_h and Mtiler (1954). and defined d e¢¢ord|nll to KII pO_Inl_I

haMrd tO aircraft. Conrail, ion stdl eKb, ti over what exacUy the Mlrm

describes: =t wdl be made ¢_ear throulh the rev_w of o_rvllional

sludiel m the n_xi sac.on thee sacral po._ibly dynam_callr d;.unct

pheno_na can qualify

D_lp=le re_ecoon of the "dow_nbunt'. there was Inlal concern

m the n_teomlol_¢el commumty and eepecmlly el tha, Natk0nal Se_re

• the work deKnhed here was l_nlomci by IJ_ Federal AvUllmn

.._,dmln_ltat_n. "the Uneed SL_tle Governmenl essumel iI_

liability for I¢11¢Onlefll or u4411IheroI.

469

the National Severe Storm_ Laboratory (NSSL) '_ith p_venung aircraft acciden_ luch al the one mentioned abov_ at JFK airll_rt, Howe_er, it apl_Jr_d to some sc_¢nt[_L_ that th= wry w_d shear relitcd

i_rcraft accidenLt attributed by FuJlu= to downl_r_u were a¢tually

caused hy aircra(t penetreti_n of _erger SCal= _u3t(ronLt. P_rt of thie

areument we= breed on deu_iled dual =rid triple-Doppler radar an,fly.

sea of tornadlc lmrn_1 In Okl_hor_ in which no small scale

downdr_fu v,¢re Iound (Srsnd¢_, 197"/: Ray, 1978). The evidence

available tn _hes¢ r_emrch_rt, sug,_,_$t_dth,_t "_cre*_ht-l_ne" downhurst

winds might w_ll t_ tho_e exper_nced _k_ng the teadiP,_ edge of _dranting gust front./. An _nemo_'Reter-L_f,_d wind _h_ir detection 5ystern was designed and l_J_Jllcd _t airports (the Low Level Wind Sheer

Akin Sy_u=m (LLWAS): Ooff, 1980) I_s©d on NSSL recommendetide Fujita (1980. 198 la) _'_nt to _.r_ _er_ths in his ¢arly I_l_rt to

explem d_ diIfcrcrees bstween down_s_ _e_J gmtfronu, asp=emily

with re_ard to the vnnd _h_r h=_.ard they po=ed for av_tion. A genePel skep_k:L1m the( nothir_l n-cw w_.,_ b¢inlg doeun_nu_d remlined.

Howe_r, Pujlu_ f_m._u_d ¢onvL_ced that unusually etron$,

small sca)¢ down, dreh.l not only e_.'._d 1_1_,po_d il _ry real threat to

avuldon. He ob¢,lin_d _c_nd_P. euFV_r_ and ft.¢_|iti¢l,, incl_lint, DoiP

pier radar, Imuument_d eb'crafc, and n'_lontt _=r_n_, for pro_ect

NIMROD (Northern [_iru_L_ I_.t¢_._k>¢_¢_[ Re_'_._rch on Downbursqi;

_th Sri_s_v_) na_r Chlc.._ in 1978 (FuJl_, 19591, project JAWS

(loint Airport We•thzr g'.,,_,_; _.h McCs_'@,y and Wi_lOn) r,4mr

Denver in 1982 (McC_rd_y et _.. 19_2), _nd a'_Jt rcccndy, prelect

MfST (MiarebL11_t_ ar_ S_vere ='T3_,U,_'_er_tor111_; w_d'_ Wakimoto) n_ar

Huntsville in 1986 (Dodge et _,, 1_06),

Afar both NIMROD &P,_ JAWS. the downbur_t was fade,

fined tO encompe_l newly observed phenomena, After NIMROD she

downbu.r_t was redefined as "•n Ot_tbuP_t Of dama_m& _nds on or

near the Ground" (Fuji_ en_ WaL:imoto. 19_1) where "damaging

w_nds" referred to _'Inds of at lea_t 18 m/l; microburt_ were Simply

wind evenU= of r,ht¢ ma|ni(L_e on a S_allcr _-._te, During JAWS, m=ny

more mic_'obur_ were f_und _r_ t,_ emphases wal ac¢ord$ngly

shifted, The mic/'Ob_r_t was redefined as ha'4_, a "d{fferenual Dop

pier v_lo¢Ity acres t_e diver_nce center _reater th-_n or equal _o 10

m/a and the iniUal di_u_nce bcc'_en maJ¢imum _pp,'o_chin_ and re.

cedinl_ ¢ente_ _U th_n Or eq'_I tO 4 kr_* (Wig, on f! el.. 19_4)''

T_d definition now ¢r_omp_Se_ weaker but _IJ|l highly divergent meteorological phenomena

A me)or imp_tu6 was added tO (he n_t¢oro[ogical investigation of m_.'rol_ursu when, after _ ¢rath of Pan Ameri¢en World A,rways Flil_ht _59 in July L952 Shortly ehcr take-off Pl New Otiean:,

Intern•uona| Al_po_ in _hich _{I 149 p,=PIoP.t on b,0ard and 8 perSons

on ¢he ground died (Fuji_t, 195J: C,1,r_cene t/at.. 1983a). e Nahonal

Academy of Science_ Committee for the ._Ludy Of Low-Altitude W_nd

Sh_lr and Ire H,,r..ard (0 Aviat_n w_$ _orn_d under ihe sponso_hq_

Of the Federe| Av_tion Adm_n_itreL_on (_AA) The final report Of

d'.al comm_tlee (Nauc.nal Research Counc_l, 19_3) S61(es that ".cell

wind sheen have been understood by h'_cteoroJOg_Lt for | number el

ye•rL These in¢lu¢le those found in gu.sI frOnt_, warm and cold airn1•l_l ffon_, felt.l-." en_ that "rP_$L Io!_h_) are pranK:table.

tOn_umea hour_ In _d_nce." They go O¢1 to not_ that "Sci(_ntL_u[

have recently _£un m recognize th_ importance Ot* storm downdref_

thal are unusually small m honr_n_l ¢ro_ _¢tionS Ind thai are of

si1Otl dura¢_on. Such (_owndr_f_ _ve _;'.en c=l_d m_crob_r_ " Th_

meUlorOk_K:•l cOmmunity finery _em_d co_lvinc.ed of both the ha£-

etd O_ Iow-albt_¢ wtt_l shear to av_,=t_on ,tt'_ tl_ e_tence Of

microb_esU (_e=_r, |985).

The Na0onal Academy of Sciences Committee ml_de several

recommendation=, one ot whJch _s thai the FAA "take immed_ale

teflon tO dcve_:_l_ & pu_ed Doppler radar system that can t_ u_ed tu

o_:H_rve _e•ther condition_ at _nd around a|rpon, term.'tais. This terminal radar sytlem _,hould _ able IO ope_te wi_h a h_;h degr_= of

'-_he SiC_(_can¢¢ Of _© 4 km sca_ _3_=¢ently Ot.gmat_S from =he

plane=ry _:ale defl_d by Fuji= {198 I b), The eanh'f ¢lrcumferenc.e Ls 40,0_0 km ar_ _'a_ _iv'b,o,_s are made m ueps of t_)

orders of maEn_¢ude eech, at 400 km. _ km, a_d 0,04 kin.
sutOmat=on end to provide in(orlttettofl on |Ow-Iltit!._e wind similar.

tu;t_ulence, and nlln|ag inter_llty."

"r_e MIT L_o_ Lel_olltory. u_r contlll¢t to the FAA,

b¢len m 191|2 th* de_iopment, ol en FAA pube _r .me,let

rad|r teethed to be _ for _ dete¢_On o| I_lull'do_ ev_ltlon

weather in comus and tert,nlnll eln_p_e (Evin= end John=on. 19&4;

Laird and Evmnl. 19|2). The p$_l_ i_j_20tted _ d_._k)pment of

Lincoln (,etched (and the trwteoroJo_..lll niNat_h on tow-alihude

,,and shear tn _ JA_ prote¢t) under _Li newly contmen_ed Terminal Doppler Wes_h4r il.lldlr Pmsnlm, The trim_0nJi_ rt_lr (called

FL-_.) was _oved to Memphuk TN in m_*1954 and ol_raled dunnt

lC,85 as par'. of the mule-year FLO'_3 (FAA-Lin¢oln Laboratory

Operauonel Weather $tudees) Prol¢ct The rtdar wJLsmoved lglln to

Hur,_v,lk=, AL m 1986 where the FLOWS Protect iomed with the

'_flST project in the Cooperative HunLIvlll¢ Met©oroIOgM:ll E_oeri-

_¢_t (COHMEX). MIcrol_u ,*,ere indeed found end dau=icLs w_th

_c=nnln| _'ate|=e! sul_ble for uf_ in in lU(,orrAtlc mM:roJ:)uIl_t detection sysu_m were collected Most m_¢robunu m MemphL_ and

Hun'.$vtU¢ _1_ cl_¢d by the coIl•l_ing phas_ dow1_dr_fl.I o_ _oL_tcd,

ate-mass _hundel_tOn_=. sod _era e¢comp=n_ed by very heavy rein

Th_$e storf11_ ap_llf (o _ V_l_ similar [o thol_ that hive caused a

argo n_mbef of a_rafl section,s (see e._. Fuliuz. 1955).

SinCe ihe h'a(ionsl Acldemy Of _(;c!ences Co_nmltLee n'u=de ;_

re_ommendauo_, another llrerlft accident occurred that has been

attr_hutcd to mKro_ur_| wend shelf, Th_ was the cr-esh O1' Oeha 191 _t

Da;las/F_ Worth in Au|ust t985 (Pup_, 198_; Carotene rt ai.

I0_6) Effon_ arc no_ underway within the r_lentll_ and engineering

ccmmunlt,eS tO refine techniques Ior |utoma_d av_t|on-hat,_rdous

,*cachet detection _th the Terminal Doppler Weather I_ldar$ (Ev'lt_

and Turnbull. 1985; Zorpette, 1986) The FL-2 radar hss been

rooted to Denver where, dunn| the 1987 m,croburst seasOn, many

ex¢cllen[ da_seu vnth l-sin, surface update rates and coverage of

upper level storm Stur_ture were lathered Lincoln Laboratory, NSSL,

and NCAR w;!l be demomurl_n_ the {eesd_ili(,y of pro_K_ing reel-ume

Iov.-sltlt_d¢ wtM shear Intorm4tt_n to air tnlflic conu'o|_er_ at Den-

_e:'s Sc._pk=ton alr3_on mn _he summer of 1988. Th_ mk:mburtt deue¢-

hons w_l] be sen_nlted by automated algonthrni developed at MIT

Lincoln LabOrato_ thee opcnl[e on the FL-_ DoppJcr weather radar

d=_ (Merrier. 1987; Campbell, 1988).

3 OBSERVATIONAl. ST1_nIES oF MICROOURSTS

In thul lecu_n, a num_ber of itudle_ pertaurun¢ to mterobuvsUI

(those perfonlled before 19l?) are I'_wewed and lummlrur_d. The

re,,_w _ divided into catelones pnmarUy to di(feren_ul between es-

_nu_lLy difien=nt phenomen_ (.hit |l,_ rt_ to mk:mt_n_u; however, it

L_ Shown thee Iome cM,'lones arc not dLtttn_t.

) 1 Spearhead echoes

The parent storm tespot_ible for the outflow in which the

Eastern airlines fli|ht crashed at/FK in 19"/3 was deuSrmmed to be l

ty']_ Of {solaced muZti¢¢ll storm, rouihly 3a km |one, vmith occurred

on a day w_th numerous scattered cell_ of veriou_ sizes The echo took

on s "sPearhead" shape |n the low resolutmn radar PPI films (Fig. ])

t

Fi I 2 A .,o_lel O[ o speovheod eCho/yore Puy.d _ed ByevS 11977)

Uousual s_rfe¢¢ ¢onverser_e both from old thund¢_torm outflot_ll

aria I *elk Sea brecae front enhanced the Iro',_h of new cells AIthoush the ¢ncoumer_d out/low was flit cbIMif_d IS a downbu_t, a

rev_,_d St,,.'ey showed t.h_! e nwnber o( smaller mKrobunu, were prtsent (FujiUL 19l$), A more detaded dtic_mion Of thL_ tyD4 Of storm _=

presented in section )6

) 7, BOw echoes led do-.nburSts

_(ter further obsen|t_onal work a more genvral :)p¢ nf echo

_*th _.h,ch downbun_ _re asso¢_lted was mentd_d by Fu/ita (1971)

as (he "bow" echo which then _kes the shape of a lp(arhead echo

dur,n G the $tron| downburit suzg¢ and whKh somttlmes develops a

"*¢ak echo channel" at low levelS in _ area o( stronle_ wands (Pi I

)l Tornadoes iollrHItlnles develop on the cyclonK shear side O( the

ares of high w_ndS or in the rozaunl head (Smith and Plrtac=, 19115)

The m_:m ;"n r:E. top tx'comcs dilpbccd ahead ,_f tl_, _trOnl; relier470

•iLL t._qO lOW ¢_O Irle( col_i (o_o Iriet |

!

EVOLUTION OF _OW ffCHO .._. e ._.,_..,,,_

Fi I R Evolution of bow echopvoposed by Fuyit¢ (19a/b) /n th;j

model a #ow echo t$ prod_cedby d downbl=rst fhuflderl(orm os tke

downflow coJ¢odes down Io the Iround. Finall_ rhe hoNson/al [lOw

Or _ wtt_kCnJ_ downbur$t /nd_Ctl o melo$cole clreulor#ol_ which

distorts Ih_ I_rial I#le echo into O commo-shoptd echo wtth o

rotatln I head.

tlv_ty gradient zion| d'tc |eading edge of the bow at low le,,eL_

(P_ybylm_ki snd Oery. 19_3). Sat.ellite an41ya¢t hxve shown Senersl

cloud top warming in ad_nce of the downbun;t fornr_tLon, md=cat,nl

collapse 01 the cel_ (e._., Fuiite and Wikimoto, 1981). Fullte (1979)

a_,o notc_ that a hole may appear at the edse of the echo at high

leve_ (Skm); in sencrtl thu_ reflectively notch L_ ob_rved on the

upshe3r side O( the storm iy3tem, _ e. (,he side upon wE*oh Ihe en_lronmenU_[ winds are impin|ine at upl_r levelS.

The bow mhaped echo d generally pitt of a synopuc scale

squall line (Wol[so, o. 198); DlStefano, I98.1), pan of a m(soscale

linear echo confilurit_on or cl_r (FujiLI and Waklmot0, t9$h

Forbes arid Weklmom. 1983. Knupp and Jor|erden, 198S. COOley.

1956), or a combination of supertel] and we.aker llorn_ (Careclna.

197a: Schmidt and Cotton, 19|_) $im",.r IKorm refleCLwzty p=t_rnl

have been called "l_ne echo wave petl_r_" or LEW_ by Nolen

(1939) end Ham_kon 11970). A resurm¢=d term "der_:ho °" (Hinr,chs. 1888) hal been _q_d by d'to_ with operaUonll e_er_l_e tO

dcscnhe some four dtffe_nt tyl:mS O[ 1411_l:rewe&tMr prodte¢it_ mesoscase COnVeCtive sylcemz exlllbi(,m$ bow echo chdlrtcter_Lk;s (JObt_

and Hin, 1983: P_ybyU_ki and _eCl[n:, t985); dlese storms all

have e;ther or_ I=rie Or nUlY_rou$ SlTulller ¢hlnhelS Of weak echo

_)_hil_ _e rlMin Cel_i Eik_ and Oe_lk (1989) no--- that OKIil_Oma

downbunt_ OrlOn h_ve asymn_u'_ s_l_lCe w_l_l sheer petifl_ whch

mike their =uen|;h difficuk to estunru=_ =,ithsingle _pp_¢r radan.

Knupp aM Jorlen_en 11985) llud_d m downbuPlt-pl'od_.mnl

bow echo =mrm that developed in lOuO_lulmrn l(ilnils In in environment charactenr.ed by =rnodemtely low" vdnd shear, abundant moBtunl up to 850 rob. and | _eerly dr'/edMbetJ¢ Ml_l rtte up to 600 rob.

suthoI1 ll_Jy'&_d P-] |lff,,r=ft data, In¢ludlt_ airborne Doppler

rzdir data taken flair the weak echO reltOn of th_ bow j_st liter

damaEIn | suJrface wixKIs had o¢,¢ur1'1_. They concluded that, neptive

buoyancy ere=ted by melon| and evtpottuon in the locust 2-] km o(

the storm clt=ed procure I_Juedonl O[ up to 1.6 mb over the blrse

str=tlform rain rellon behind the bow, is air parcelS were accelerated

downward Schmidt end Couon (1985) show. for I s=milar storm, a

Siront in_,ow from the rear of the storm d_rectly mto the vertex of the

"how" at 5 kin, apparently in responSe to chili type O( large state

duw_ndra(t Th_s larj[e SCale dowt_lreft geherated a _tron$ low-levi

ouiflow wh,ch reached clamalin I speeds when convective scal_

duwnd,.fL_ of only moderate m(,ert$1ty _ere superimposed

A itudy o[ Syt'_l:xic and r_so_at_ [S¢[O_ as&oci;Ited u,lth

doWnOurst prodt_in| thunderstorn_ by Forbes el _1, (1980) el'mead

_;_at a marked low-level (8S0 mb) Ft was alwa_ present aS was a jet

slreak a_ the _00 mb _vel. implying the po_ible impotence 0[ a c0upl._& o[ _l_e two and the po$ltbIJlty that the nu_ 0t' t1_mefltum from

ehese _e.els tO the surface Could at leeS( partzally account for the hq_h

_p_ed obdk)w winds They also |ound (hat suIbdity ,ndJceS were sener-

_tly tndJcau_ of ¢on._lderable Ihunderltorm po_ntull, that the

Weclpluzb|e water toni*he of the au_.oephere wa3 high. and thai the

1000-500 mb mean relauve hutmdity wu typl¢&lly moderate The

downbunu SltJd,_l were often I¢¢Om_nad by tornadoes I:n_t.it wli

not deu_rmlned if the en,nronmentel condkmm whKh tend to pro.

mote [he t_o types of atom'= d_ffer,

Damage Surveys by. e.l.. Forbes and Wakimoto (198}).

Fujmte (1978). lnd F_i= e_d Weku'noto (191|) revelkd dtt( small

mlcrobur_u end tor_do_, twtldn I do_bu_llll, and other r_lt_l_ll

aM dlveri_n¢ w_nd pett_rns ¢oin¢idently occurred. "J_ul led _/I/OlfSo_

(1983) to hypoU_ai=e that s srnllll Kale occlt_r, ton downdrllf[, dynaml.

cally induced by low preselunl as_x:u=ted wqh the stron$ rouluon at JOw

te_,¢ls. *st forcin_ • smaller _'.Jle m*¢robunlt w_hin a ilrser scak

thunderS.ore OUtflow, and that rhis superpos_lOn caused the dal1_tl;-

in I mu_face u_ndl. TIN: snuill scsle dowhdraft was thOusht tO be essen-

• "D_mcho" el Sp•nih (or "itteilht" and _ u_d to desertbe Sttll|hl

[i_e u_nds lUSt as "torRado = ,- ulld to (_ri_ roultiOnl| winds

D_IGINAL PAGE IS

_K)OR QUALITY,
tu=lty the _rne as ,.hit Q=:ckallon do_ndreft found by Kiemp and

Rotunno (1983) Ln s htlh mmluOon numer_._l model o_ the .U>rnndt¢

rel_101_ _n • s_pl'rce_ smr'm.

In summary, them orltmzed downbu_{ I¢ornl occur

throulhout the CoN|nen_l US l¢ Umel of _ yelr wheh lynoo_i¢

l{ale inl_lbi|ir._l dol_|l_lte _ inll_ll_r _l|uIrnl (typl¢llly Utmu|h

tendril pllx of _ {ounur_ d_rtfl I Iprtn_ end till; {ll_l" _f_h dUIql_

early and 1lie t_lltmlr). They develop In en_nronmeflts ct'ulracaertz_d

by moderat _' vIH'tieal Ihear O( she hoftlontel W'_M. Ir_ltabl||ty or ¢Ondtuonal ir,jtab_llty, ind abundant rnobture. In the tales _nai)n_ed. a

tayer O| dry air _11 presllnt al mldlevel= These bow e¢ho itorn_ lien"

erllly Ire pats O| • lar$¢r meio_cak_ or _ynof)t_ Kale I_orm complex

Or Ironea! bne storm, ha_ hiih rider _nec_41y leveb (It hell[ J0

_BZ), produce downburm that are qu_te blrse (typ|cally 20 km or

more across), -nd often con(am embedded microbur_ and _ornadoes. With SO_ con[arlene• it can _ stated ihal the lar_ sc4k:

downdra(t _ driven by the ¢ooUn I due tO evaporation and meklt_i zS

dr) ¢nW¢Onmen_ a_r enter,, the StOrm (rum beh(nd {n • n=_on o(

strauform T&t_ with $nuiIL readily evapo_ted preclpitattOfl panlckm,

and that this pro¢©_ lelds to the formiuon of the w_zk echo r¢|iOItll

beh=nd the bow. The Oow_nwaro _ux o| horltontal morn•alum from

mv:ll_veLs _ ll._o tmportjint in I¢counti[lg [or th_ high surface wad

speeds in some cases The smaller embedded mlcrobunta may be produced in a vat,cry O[ wayS. In Ser_ra[. these stonr',s are k)nl Jived with

fairly pred,ctable paths, and tplNIrently threatening llnoush that airCraft rsrely ,[ ev=:r try to _qy throulh the•re. Thus while U_S¢ stornls are

mhe_enUy very haeardous to aviation, the ha=llrclou_ _¢_on_ are prc-

_cu_bk_ _,nd ivo,c[abte '_ing the currenUy available rne_orolol_:al infofmattofl.

3 3 Bo_, echoes and microburJts

Care must be taklln when catellOrtZmg storm_ -ccordinl_ to

th¢,r rider echo tppearlnce. Elmorll 11986) discusses ehe evolutmn

of a mtcrObu_;t aLso¢[ated with a bow-shaped, low re_lectivlty fiche

(34 dBZ maXJmum) that Occurtld near Delayer. In whKh rJ_ reflectis_l'y notch wa_; ol0served tO develOp on [he downshllar I_¢ of the

_Orm cotrx:=dent wll.h antk:yclonk: retaken. The- storm• roughly 8 km

in hormonal extllnt, wl$ very dJfllrent {tOm L_OM: described in the

prll,_ous secuo_. ELmeR notes that th_$ Star11', wl_ 'JIted $_lim[k:andy

down_nd (and domh4ar) throuIhout itl lifetime, and lu_alt_ tMt

the Observed •ntteyclonic cs_utatmn might have been part o| = yen

Karmann vor%¢x pair un whx:h the cy¢lOnm half will _omchow atmnu.

at_ _ m tbe env_ronnutnt charactertled by anUeyclon_ _h_r•

Knupp and COttOn (t9xSa), throu|h tnaly'i_ a( a numerlcall)

simulated ¢onvecti,_ cloud (15 'am d_meter)• have come up wtth •

more con,nncinl •xplar_tmn. They _how that weak, Uhlld updraful

lilow precipitation tO deKend to Io_r level= where downdraltl arl

produclld, and that the flow around _ updraft at rnidlev_b syltentlU.

tally [rarapor_s precipi_tJon to the= dow_lha_r eel,on (F_ 4; _I¢ aUo

F_l.e St'hfmotlc dialram ,llultr¢in I wait, rmrammam withm lk#

downsh_ar flant of n conv_cliv# cloud. The :7mboLs H and L ellprelim kilh- end Iow*prllSsure /_r, urb_iwu 71_Je perturbolio_,

¢1lo_ I with Iht verlical _or.c#7 pelllern_, are pro<h_cld by cloud verItC(JI molloR Inte¢oCtln_ With eeviro_memal flow increas_ with

height ixt lh_s case. From Rnu_p and Co_to_ (19_l_b).

HeymM,¢id. e_ el., 1978). Tl'4y also note that the equivalent po_nUal

temperature vah,,_a in the dow'N_heat alton were ¢lu_¢kly reduced at

the dow|)draft m_tured, and thai "Lhd p_oCela ptov'tda.s • rn_LPX_ I_/

which surface preecipmliion may nearly co,m:ide ruth developm I

downdralu and low-valued equtvalenl potential _mperaturll air..."

Althou|h no drirr._t¢ vOrtK:ily de.loped in d_ w_ke r_$mn of the

model cloud, it t_ quire plausible that vllrt_ll lir¢(£h_n I in a limiblrly

created downdrah concentreuld the aml_ent anu¢)_:k_n¢ von_¢ity in

ORIGINAL PAGE IS

0._ P_OOR QUALITT_

Elmore's omerved bow echo tad edcmburtt, Thl= tylx of "bo_

echo', then, |co,ttUy be, lonll _ drm fOl|OWt¢t I ¢_UIlOry (section 3.4}.

3 4 Shellow, hilh-blumd ¢umulenimbull clouds

Since th_ JAWS prO_"t _1 1952, a |real dell of attention hit

been given tO mtcrobunu which or_imlta from beniln-tooklnl, hilh-

_l_ed (-4 km el| ), •ha|lOw (-2 km dNp) strltoeumu]_l or cumulm

cor_cstt_ clouds. T'nele clOuds often haw |lacblted tOpl and _ck the

rapidly rl=il_ I conve¢tiw m.,_rl, thtutder, led Illhtrdnl of typtcel

lower-based cumuloniml:)m clouds (WsklmotO, 1915). althoUllh lame

trait| convective turreU can or,.¢laton_lly be seen (H/elmt'elt ¢t at..

t986} Vtrla i_ commonly v_dbk below cloud btN ([iv_n_ r_sll to the

term vlr&n mtcrob_rst$) _st often ltttll or I_O rein f_t¢l_$ _te £round

(Fuji= and WzkimotO, tg$3b). Bralulm (t952) briefly menCioP, ed this

phenomenon, and Krumm (19_4) ¢htract=rtzed the "dry thaMesstorm over the plateau area of the Unhad Statel" with, m flu'aspect.

oral•in I l¢¢urlcy. Brown et at. (19112) al=o documented this type of

storm, and noled that ILl danut$lN outnow could qualily •s =

downbur;t. They also predicted what the JAWS inveitlgaton wllre

soon to discover, that thu; type of storm is much more common {hen

wet ¢llneraily recoKntzed at the tim_.

Attempts to $ehem|o.e the charactllE_st_cso{ the en_nronmef_t

in which this type Of microI0ur_t forms, primlri|y lot fOrectstin$ putposes, haw been quit_ succll=ful. Carotene. ll_ el. 1195_b) and

_Jakimou) 11985) found _hat a dellp, dry sub¢_oud layer (dew peat

depression treater than 30eC) with z nearly dry adiabam: ),apse rite

was common, ar_; that a molar layer around the _00 mb le_ll nearl),

alway1 occurred, Winds typically had a iltort_ w_tterly ¢omponent.

and increl_.d with heq[ht. Ulml a Ik_ple rult that CM dew pein! depreuion tt T00 mb be $_ater than |*C and that k be l_t= this 8"C i[

500 rob, Czraeena, •, al. (t953b) w_ra lbk: = corr¢cdy Clettify 26 of

30 days on which dry mtcrobunl_ o¢.¢urn_.

Radar and flow chara¢tt, tl=bcs o( th_s type el storm have helen

documllnted by Wilson, et el. (1954). FUjtt,I and Wlk,molO ([98_l),

Rol_n._ and Wtbon (t9_4), Hj_lmfeR (19E4), MUEIIer and Hildebn_nd (t9$S). Fujiu_ (_,985), Eihlom (|956). end lumn_rt_.ed by

Kes4in_er, e_ 01, (_986). Stsds_k:a| re'_Ittl of rUt{ice n_$one_ maa,-

uremen_ o! JAWS mlerobtmltt hays been t_mm&ri_d by |editd tr,_

LeFebwll (1956). Thai* mk:rob_rltl alJ IOrmed betw_'.=n 1300 and

1900 MOT w_th 7_% occurring beew_en 1400 and 1700 MDT

Rll(k:ctivicy values were Iiwlyll _IM that 30 d|Z It _00 m ,||. The

evok, dOnot the surlace flow [i_M tyrol of nearly all m_¢rob_r_L¢

ohm:fred durin| JAWS is schemaucally illmtraled in Filure ¢, "r1_

] L i ,_-,,

/.311_ ,,

0 I =34 S

L_L_LJ,_LJ

'J_aL( tvmt

r.fO_

FI$ .,f. Vertical cross section Of thll evolution _/ the microburst

wind/ieid be.fed on JAWS data• T i_ ;he time of ini(inl diverlln(e

at the sur)',*cll.The shadlnl refllr; tO the vector wind speeds From

WiLton _t, al. (1984).

horizontal vor_ex roll •t the periphery of the downdrtfl. (T-2 Min _n

Fit _) led Fujita and Wakimoto (1952;a) to define the "m_d-air"

mKrohur_t; Roberts and Wibon (19Ba) ihow_d that thL_ di_.er=ef_e

aloft pr,marily occurred tot the low SeleCtiVity virla merobu_3,

Observ_UOm ba_d on all mk:ml_nlul i_ JAW_ (ap_o_umttely haft w_t_ uasoeLtted with vir|t Of lilhl; faro) thee that theft

no COrreLation betweafi radar rurk_tiv_ty Or iqrftce fll|fd'i u rite and

the aubeequ_m _renlth of _he _o,, (McCarthy, et oL. 19_: Fujitnd Wakened. _953b). Rai_al! ,'a_s never exceeded } inches per

hour. and only on 6 da_ was _he rain[ell m_e a_ecmed

mk:rolxm_ above I inch I_r hour. The su_l surface outflow lYl_,-

cagy leited from 2-5 minutes with O_l_flow _ bet_efl I0 en¢l 20

m/i- Fu|_ (19115) abO fotm¢l that rJ_ surface 14mperllture wll$ i_t at

likely to rim IS m fell, by is much all ]*C; Kel,lin(_l:r, it ¢l. 11986)

(OOnd a |-_IC SUdlC41 temperature drop end no rain fer the one case

d_y d_scu_

Brown, et el. 11912) hypothesis4 thai the ¢ombinllUOn o( the

deep dry sub¢loud layer albWlnl nelaUvely l_Oyant lair neat cloud

be_ to d_k;end to t_t surface wkhout Iollnl ill of _ ne_tiw buoyancy (end to a¢(|;eleraie Over e If•at d_JIr,¢e), and eh_ weak updrafu

produem I smlll precipitauon pan_:kN whk_h evaporate lad reel( more

471
o o

nlp_ly than 0_1 larler l_lrl_lm fOrmed in more _tioroul con_c_n.

$_s_i_ elgin), uttnll a almple omP<llmer_ior_l O,me--del:_l_le_ model ot an avaporetlvely dr(v_n downdrlh, a_l_moUcaUy

¢omlide_d the verlOul faclorl d_t co'uld lnfllxnce Ihl ultimate

strereth of the d0_mdm|t, He found _lt imenH downdtallj _m

(avo,ed when _: _ps4 rate _,ta clo_ to dry adlab&g¢, when the amwirer mlxJn I ra0o near cloud blll_ (ori41n of th4 downdraf 0 will h41h•

and when the dowT'idPIft nldiul was si lea++[ I km. _flvllltlvl i1_1o coniirmed lh.lt "11 IJ_n _mwltmr content dutrilx_d in smaller dropS is

lenentity u mo_ e(fk:_nt pro<lager of coohnl and m_ru_

downdr_ft$ °, but dKI find thai under rome c_rcun_mncea brief dropl,

_ Lhe:r Stellar _rml_l fell _ekX:i_s, were able to produce m

deeper, au'Onler downdratt by epr_adln| th_ coohnl o_er a Ir_eter

delxh He lal_o hound that the rebuke humidity of the env_ronmenL in

t,'_ =dealized but not mO far from I_ahil}c C|$¢ of _3 m_inl_, article

ihe _owndfaft O_ly indirectly by affecting I_ buoyancy. Thus a Vll'tua'ly wam_cr (more hu_mid) atmosphere would actually be more cond_l-

¢_ve to stron i do,_drlfu

Krueler and Wok,mow (19L <) ueed _ two d_men+ional

eat.symmetric hum•nell cloud model m simulate the dry microburst

LI+e c)clc. "T'he_r rcsu?lJI b_stcally a&_ed with those of Srivlst,llVa

(lg_5_ I_Jt _,mC© _hey included a _Ower boundary, the attamed downward v_iocIIh_$ were lOWer, as expected. They found that the ve_icaJ

velocity deer•lied appre¢mb_y as the radt_,s of (he mit611 rainwater

region was increased but LhJIt the lub_equent surface outflow vek')oty

mcrealed only Sl_lh,.ly Thll _e_lt _ more generally appli¢ab_ to any

_iO_lted downdra(t_ the cylindrical g_ometr_ and m_a cOnOnu.ty

alone de_ermine that the rauo of the outflow Ii:xed to the dow_flow

speed _ a Imear funcuoh of _ m_tml rld_u_ of the ramwat£f relPOn

(_/W . W2). Although _t "*,aS not db_:_l,l_d, the nurr.tr:cat model

output dau= pre_nmd by IJle euiho_ d_l fall along a strlliht line

(LT;_,V - P,/3 t 0"_5. where R ,¢ m km).

KP_eger. ¢,/ol (1986) u,_d ohm same model to study the role

ol _:e-phase microphyll¢l m determminl _e downdra|t and outHow

suenlth O( dw mtc_0b,4R_. T'My performed expenenenU_ in whk;h _h¢

pt+c_p_oon dropped el the lOp o( the model cOl_l._ted Of eiihlr rlln.

eraupei, or snow at each of rome cloud bale Wcc=pi=uon r=t_l w_th

KientJce] radlal d=ttfl_JUOns. They foui_d thlt In4 mote preclpllJt_on.

:he stronler the dowlldmtul and lU_iii¢¢ OUd'lowl, and that them ,,_anatton_ were mUCh LtPler than tho_l altnt_l_bM to the dlffe_nt forms

o1' prec*pil_oOn w1121 the Mm_ cof_¢4;nlJratKm. Ho_lwr. for a liven

pRmpt_llt_n nl_, ram i_lmlly prodQ<ed the Iuonieat downdraft

and $_upel produced the coldel6 au_onl|es_ surface oudlow. The _uo

of the out/low to _ downfTow speed wel alwlyS l.,'i'lallla| for mm and

_arlleSt for lraupel. _ emphasizes Lh_ Impol'_nce of cha venicil

d_ilJ'lbuOOn Of _lll_Vt I_loyaf_y On t_ _It_ Of n_ix_'lum OUt}lOw

ipeed to ma_Jmum downJlow timed for etorml of equal horu_ont_l

scaleS.

Mahot_¢y (1983) developed in evapofauon modei to esumJ_e

the sulx:loud coolin I rims m JAWS m=:tobum.S uam I aircraft-re©atur_d hydmmeteoe 1t3_cl4_ (ROd6 4tl ,_/.. 19|)) and ambient ret_l_v_

hurmdi W veh_$. He found a ml_dmum m th_ codlin| rim just below

cloud bal_ where hllh ¢oncenmldOn_ of tmlll ice parU¢lel ware pre-

_nl. Us_n I equIval4rK po_nmll taml_ranull i$ a Iracer. he found that

a_r in the downd_ft w_S orillnat_ll it the bate of the c'_nulus

cloud, and not from wu+hm or from the top oi the cloud. He, too,

concluded that liron I dowfldraft4 Occurred _th a deep, dry adu_beuc

suhcloud byer and a brle concentration O( |m_ll ptrl*ck_$, but fOr low

:e_luve humidity vilu_$. It I_y b4 that _h hqlhef atmolphenc re_-

Uve humidity VlhJ_l. different (OnT_ Of cOnvectiOn ar6r_ Rodi, rt o/

(19B6) reed a s,milar model to cOmp_te the maximum coo_n G ra_s

rgsulbng from imtml ir4upel paP,_Cle den_u_ of 0 l and 0.9 illcm _.

w_h a ty_KatLy ol_ers_d s_,e spectrum, and found them to be, _ry

ddferen( Althoulh th_ veRlcal equation of motion was not $oJved,

_ey too concluded U_t kno=,tedl_ of the p_ec_piuluon ra_e or pan_c_e

cief_l=ty i$ ct_Kud tO the undlnblndm| of do_ndraft rr_ln_l_d¢l.

CompenMlin_ convarience muJit develop at or above LI_

downdrMt tn,l_UOn _=( tO repute the der_end_n I a_f in

m¢r0bur_t. Th_ dowmm|rd motion aM conwr_ence _ Increale

venial voru¢ity in the Mm4 relNIn. $_rl_l_Jnt converl_oce, ir_Jud*

,n| s:nkinll of the vMibkl ¢10_ into the dlo_mdraf[ region haul been

o_¢rvad (F_)i_, 19S$), as h_a m¢reateld rotation cmocident w_th the

downdraft aM rell_Cti_¢y cote (PuiiUl and Wak_molu. 1983a; Roben.I

_nd Wil_on. 19114).

In $umn_lry. all 0_:_lervll;On$ and limU_lKhl_ ifl_lcale {he(

do*'nwlrd lCClJenllJ0n from n_gall_e t_joylr_y, lcnerl[¢.d II pre¢ipit_t_on w_th the typicall_ ob_r,Rd d_tftb_Jt)On of enM)ll dropS falls {tom

cloud ba_ imo the daep, dry ad_bitK sub¢loud blyer and eveporaml

(and melu), can lead to d_¢ Oi_lrved downdrif( sl_edl in Iml

472

m_:vo_r_t_ or_0m_ IImm sMliow, htth-lw_l _uloNe_.b_

clouds. TM coNllUor., _..,_at_ for d'_ f¢,rm_ of _ t)l_ of

m_robur$l h&_ mllnly been 0bNr_KI in I_1 h_h i_a_l Mlt 0f

Rocky Mtm. d_'tnel _ automat monthl, ellhouIh they Can ¢eM&_ly

Occur ItSewhenl" . [L it prol_bll INkt the dawndrlftl enl ort(_f_lly m-

_tlel_d by pr_ctp|tadon loadln I _ the el_veted ¢loudl. Th_ $mMlll

hor_ontal lea I_ o{ the phenomenon hat not been IId_uamly Ixpb_d. but It cannot be decoulN_d from I_ I_ale of the orllmal

updraft. U_t aS. _ preferred |¢ele 0f the lnl_bilRy tha, t ¢_ted the

cumulus cloudl In the fJri[ pblce.

Model resulu show thJt the tlelrro_lt dow_l_fLI wall be the

mo_t hazardous to =_ltion; hOt only w_|) (ha vertical _elo¢itms I_ the

sl.rOngelt, but the outflow _tnd_ wl|l I_ neatly as stfon I as th@_ t'l_m

la_er storms while _c horitontal Kale _1 smaller. The actuJI haurd

to av',atv0n Of thai. tyl_ of m_cr_l_tnlt t_la be+an IMoMed through obeer.

vlt;ons Of air traffic responle by S_'venton (1994. 19B$) He Iound

that airt_ift do fly throulh m_¢robu_l.= at Staple.ton ante.in&lionel Air.

port _n Denv_¢, and [hit pilot mpOru of encountered _nd _hear are

used m *'_rn subsequent flllhl.i, l]eca_l¢ theX mK:robur_Lt 0<cur only

Jn (he afternOOn (daylight hOur_), and be¢iume they are often marked

by wrL_a _:_ow cloud I_r,_. pilot_ can lolnetiPml$ avoid flyt_l throu;h

them. The Surface r_flectJvity values of the_ mKrobu_lu ire low and.

because they OCcur in In olin (hi[h Clutter level) env+ronmenL •

Doppler radar w_Lh $oph_lilc•ted grOund clutter eupreesion Cal_Od_ty

_ r_qmred for their effe¢'avt detecuon,

3 S MicroburSt lines

The ot:_ervat[on [hat m_:roburllJI occurred in "|ami1_l" was

(iPst made by Fujiut (19?8_ I>lled or_ damm&e a_u'veys, Dutinf, JA_,_,

it was found that two Or mote mm:f'obterlt, a could Occur limUhjIl_ously,

forming a line (Ke,Mlnler el of,, 1913). Hlelmfelt and Roben_ (19|5}

dcline the m,¢rob_t I_n¢ aa co_lllUn_ Of "t_O or mote m_¢tOIl_retA.

at leas t- twill IS k_l'_ M b il w_de (INHw_en v_y max.llna on ehhef

side of the line) Ind hJIvilxll i _lk_Ky difl'en_nlial in the ¢ro¢4-ti_e

direcnon meetm I mlgroburit cnmna. A ma:rol_Jr=t lir_ may be nearly

homo;eneou_ along itl _,neth Or may be n_de up of ddt)rx:t, d_Krete

m+crobut_Ul," A preliminary Ichcmatl¢ of the baSiC m_¢robunt line

stPu_ture L_ shown in Ell• 6.

H_lmfelt and Roberu, (1985) have found that mitt•bUrst

hnes are produced from hmh--_r, ed shallow cloud line_ 1"here orilina[ _toud liras may he mitiatcd by surface ':onvcrie_e lines {hat de-

. _ ..m] _, /

'-I

I_ll(_dl, IIIStelIKeL l_ll

,d

: ,.,,.,....

; t',/:PP¢,,

-...

t .Y-'. f

Fig 6 Boric mlcroba,_t Jme JtruCmre by StevenSOn {l_|J).

,<_up dally over the Rocky moun'.ains (Witsgn and $¢hreitlef. t9|6),

nr p_rhaps m response to oroIraph.:a|ly forged Von Karman-like vortex Strecu that. are *el up parallel tO the prevailin t ands (flu#m,

t98_; Peter+on. 198S) Th_ lil'_s @n_mUy ha_ emhedded centeMt of

d,vergence zt the sod•c•. ¢oiOcident _th k_llll maxima m the r|da¢

n_l'_Ctlvlty (ield. Whereas • $i111(1¢ microbur_t all|ha have I hfet,me On

:he order of 15 minutes, the trlKrol_tjill Ime typically I_$_ for shout

an hour.

Stevenson (19B_) hal ihown tha{ mk:robom lines h_ a _-

veto impac_ on lllirpon operations primarily b=¢Su=e they arc _0nllived and propalate slowly (mean el>gad 13 m/s (HjelftJelt and

RoIxm. 19115)); however, thm abo imp4iea an,It they Can be more

cailly predi<:ted. Usml a quas,-compmuibll thrt, e-dimeMioru|l nu.

mer_al n'H_del. Andenon el oi., (|9S_) Ih@we, d (_t I_rltnl_

mi_.tol_rlt OUI._Wl may poll !an even i_lt_r dill_t to IIit_WlllOn thin

$01iary 0utl_tl for t_o NISOm: the IffKU_I dlwrllnl oul_w deplh

increases and thue m doll the to_ll amount 0l ha_ulfdOul ImllMCe,

and the _ncrea_d homonl_l pressure lr_d_nl._ can lead to even

s_ronEer, more divergent out(lug.

In summary, the etrenCth of the mlcrol_Jn= hne Outflow lnd

the Currespondin| hl_.ird to iv)at)off can viry tremendo_ly. AI-

'Wieler (l_rl_nai ¢ommunlcatXln) hal ob4efv4d m_¢roburSt _41nd

_t'_ar I$1ocmtcd w+th a _ry low nlflectlv_ty atoffn nell' Ilol_mn. MA

_lth tl_ iI.Jlylheon Co. protOtYll:l¢ NEXRAD DOl_er wellhet fades

-........ ---.1_, PAGE IS

0;_ POOR QUALITY

•)
4"

+

_,.ouih mk:mburl_ t'a_ been _xerved to [orm tn Iroupl or "fanuL_s" m oe._r peru of me counu'y, the xSenUflcaUon of the nucrolouem

al • new I_,0m_ type aro_ from oti4rw_Jom of muie._r phenomena near _ ROCgy MmL lullel;In I orolriphic InfluenCes in b_l of

sard_.at_n ol d_l ILorm tll_e. _ primary concern for ev_tk_n appeePl m be the learn impect t_lt e sk_w-movtnj llrge scab storm

vath embedded dtverE4n_ ouU_O,_ hea on alt_x_r_ openltions.

36 Atrmsss thunderltorms

One of I._e Ibl| INIr_nt cell t)_0e$ tO be lMiOCUlied w'lU1

r_._cre._n_ w_t _e isolated cumu_on|mb_s clo_d (Fl_. ?_ . AItho_lh

:: • . .

, - ." :- . . . _.._

' ' I

I.,_

..."/.:.- ...... _

Fi_, ? CofldN_o_f Olaf might Dr expected _n ,_ Ihundcrstorm C¢1/

:a the m¢_tre tta_¢, F_Om Byvr$ _nd Brohom (1949)

called simply "thunder_{Orrm" at the ume. Byers and Sraham (1949)

measu_d very leon I. small scale dive_ent surface outflo_ thet

• ould today be classified IS m_robUncS (e&., "When the cold

downdrlft o[ a ¢e[l r_acl_s 0_I surface _lyeel o[ the It_here, it

spreads 0at in e fashion llml_r tO t.%It of a nu_d N[ strlk_n{ a _I(

pga_'), Based on the numhar of faullitleSthat have occurred in wind

shear re'-ted lcC_Jln_l, _ ire _le $1OrIR_ that produce _ nlo_t

h_rardr>_l fo_r_s Of IOw-lILit1_le WIM their The n:selff;h quesoorl

d'4n Ncomel how to dbtingmsh |n ed_nce the thunde_s_orrm that

_ll prod_e v_olent oufflovn from those that w_l pro<lu£e outflOw_ Of

Ordinary strength

Airmail ltorn_ ari common m aries of con_cOve immbility.

_igh s_r[ace R1"ti_ humidity, and |itl_l or 11o veri|cal v/led lh_r.

_mplym| that. [hey eOU_ ocCur O1 most any per[ o( the countqrdurinl

_he _umrner mOnths. Dyer t_ ol. (1916) present Doppler ob_rveuon_

of a _ndstorm ricer Bo_mn in whKh a "_rki( phenon_non" associated wnh brew ram clu_ed sr.reilh_ lin_ _nd dan_le "confined to a

rag,on le,x than |._ sq1_Ire rn_s in area'. They also note t._t none of

_he ch_r_ctur_uc _vem storm radlr s_lnltur_i were prelem 11o rider

op_rltor_ {iliad to reco|n_e the darna_ potential, A lul_lquent

ree_imination of the _Irne ce_ lho_ed a d_lorpni_d mu_k_Asll alp

mall Itorl_ with one [erie. uHI ceU end e walk echo rellOn It. the

s-HIcI In the erel of hilhllt wade.

Canlccne and Ma,lr (1979) prmnt an analylm o| a dual

m_crobunlt event Char occurred in the FACE (Fk)rida Area Cumulus

Exp_nmenl) mesonet. The cell w_.ch produced the m_cr0bursu was.

a_Im. on_ of the silicas _,_thin a di_ori_Ini'ed muluce[I line of s_orml.

hav_n I been Iorced morn v_|oto_lly aC the surface m the convergence

_one o[ t_o collidmg outflow boundane$. The au(ho¢_ conclude, at

have Others since, t_lt the spearbeed shape taken on by the radar

echo w_$ attnl_ubk_ to the ripid Iro_h of new celLs on the |de,cmE edl¢ Of [he flora. The rn_rol_ll_LI, _lStmg k_is than _ mihuteJ,

were aSsocu_Id with heavy rim and embedded in s storm _clk=

downdrah that COnunued for over )0 minmes. Careful analln_l of O_

syr_p_c Kale steuben re_aled |) I braid sree of enh_Inced positive

ven_ll velocity el_ad 01 • $00 mb meaD-low, 2) the intn_on o{ a_r

with LOw eq_vl_lnt potem_l tempenltu_e betv_en 400 arid $00 mS.

and }) intensi(ym[ ver_cal _nd lheer, as nonfl-nonhw_smd_ wire:Is

of 5-7.5 mls et 500 mb Ove_ boundary byer eaS_erl), _nd$ of $

m/s. Hourly pholOgra_hs _lken before the m_crol_ar_;s Occurred

Showed that the towerll_ cumuli tilted St_ttlfiCatit|y dowl_hea ¢.

In tryin I m eccounl IOr the u_lerved 1.0 m/s surface Ou;Jlow

secede, th4_ lUthOtl found that a technique by Fo_,ter (19_8). breed

on mmst adlabit_c descent O_ downdrift air cor_Slstlnl; uf a mixture of

mldk_ll air and u_h'aft air (eq_ll p_o_OrUon._), predicted l_4SU_ of

: _..; -F___ _._.__ ; = -

ORiGINAl5 FAGE I8

OF. POOR QUALITY

than I9 m/e. They mall_el_d _It 0_I addlUol_l _)u/ce of ne|auve

bUol_ncy couM cored D_m; l) _ me.hi of _Irl_ quln_dl_ o_ ice;

• n uunu_ua,y t.rl_ quan_y rely hey, form_ lince, wtUl the ex-ulo_inary boundary blyer foP:bll Of the mk:mbunt ellS. dl pmCtplt_UOn

c_re reerudned eloft _t,h ovendlooUnl _ of |7 k_ for 4_ minutes

2) efflcMflt enUlinmenl of mJdlevel air of low equlvl]em pO_n_

teml_m_re Into the downdnl{_ w_d_ou; mixml _h updraft e:r, end_

or 3) precip:UlUon k_adml; hoover Lhe obMr_d pred_uUon nltes

_ere too _ow to comp_mly recount for the dlitrepen_y.

TI_ su%ln_ dif(emnca between probable dow_lra/t Speeds

and obser_d oudlow spe.dl hal also been ob_ersed by Fuji_ (l_$_.

1986), Throulh anelpic o( a microbumt _.l_t CIuMd dam.lie at

Andrews APB. dlrou_h v_ual end mulupl¢ Doppler observifio_ of

JAWS m_¢robunm, and _hroush bborl_ry timulltion_ with ¢o_d descendmg a_r cumlnUh the prP.._nce of i well defined tomr it the _eadmS edge of the micmbul%t ou,JlOw w11S demonltrated. Wekimoto

(1982) hal also shown Doppler Ol_l_r_Itione of a vot_x roll el the

leading edge of a dowllbUllt out._Ow. Wari_IuJ_kJls (1985) notes thst

"the lower procure It the rotor core s¢lJ to accek_rate the surface

winds, thereby maktnl_ the lX._l center end the micro_Uel( coincident

on spatial end temporal SteleS*. II '_ hypothesized by FUj_I that :n

thLs way, throuSh vortex tube stretch;ng at the leedin$ edge of an e_,.

pending outflow, a weak or moderate downdreh Could produce suon_

_urfece winds that would appear m small p_tches ,tong the out/low

boundary as the vortex tun separated (Fig. |).

Lmden and Simp_on (1955) used I laboralory model w_th

aqueous silt solutior_s of two different densities tO sho_ the ex_tence

end in¢reisin{ vOr_Jcity Of both the prumary vortex roll at the _¢adml

edge ol the expandini OUdlOw, and I t_condlty vortex (Fi_;u_ _).

They SuPJte$l +.hlt the VOl'lJces ill manifestations ol Kelvm-Helmhol_

instability; in two dlmemion_ tlow.i the K-H b{llowa em reSV_ted to

the upper h=lf of the CUnlnt _ in this three din_mionel case "the

bi|lomi temporarily occupy the full d¢l_h of the o_',flow'. Tl_y also

no_e that an II_ady examine clrculation In the de4cendln| air _Ould

(ur'Lher intr¢4Se the inmn,lhy o[ _ l_ulry '_Or'dlX.

Both Fujiu, (1956) and Linden end Simplon (1g$_) sUlLItSt

t_t the embedded v_r_¢et in the Out_low purl In addiuor_ll wind

shear threat to iv_tlOn, and tiler the recent mKroburlt-re_lted crash

of D_I_I 191 at DMlas/F$. WoRh eney have bKn ce_Md by the do_-

ward motion on the backside oJ one o[ these vortices. One unknow_n

"

u_¢woeull&T"

s,.,,c-,, or...,.o / "_'" " "_T'_

\W

Fig 8, Four jlalet oj Andrews AFB microl?,teSl. They art: i;t

Stage (DESCBNDING) Midair "mcro_r_t dt,_Cends. _nd Sta_t

(CONTACT) Mtcroburat hits cPle leound. 3rd .¢tal¢ (MATURE)

Stretchintr 01 Ihe rin I vortea [nle_lJiCJ the surface wind r_ed_.

_¢h $_OJe (BREAKUP) Runowoy vortcJr roll_ induce bur&t _,+athx.

Fro_ F_tjim (19_4).

_s how oken and under whet condidont t)_ hilh il_ed horizon,_1

•or_x rolb wtU do_{op, In on_ m_rol_rst ob_41rved with RHIs _lken

with the FL-2 rider in Huntlvllle, At. (91211|_). hoftsonl_l vort_l_

were ex¢ited {n a IXl--_xLs_nl oud10w pool when the t're6h4r out_90w

from a newly lorraine mlcrobul_ impacted the audits {Fi 1. 91)•

These snuiiler vOIs_c_s ral_diy disSil_lted (Fq[ %) klav_l ;he 1⁄4rinse,

faltllt ave O-emllln I outwlrd it + held Of _ OUd10w ¢+u_el_t. The

presence of this type 01 well dtwk)_d _'adinli outflow wave is the

rule ,afl_er than the e_ceptmn in m¢robunu observed in Memphs.

TN end Huntsville. AL.

Some of t1_e JAWS microburSL_ were a$$oc_sed w,h _)o|&ted0

urn, ready mulUceU airmlss d_undetStonnr_ {_tt produced wry heart

rein. el(hough commonly zhe cloud bes41l _re qu;te hilh and the

storms _m {early Ion|-iiqd. One tmpceuive storm thl{ occurred r:n

30 Jun_ 1911_ I111 received conliderable Itren_n ft.|.. Kellinier. el

at.. 19113; SmKh end Werermulkas, 1983; Wtlsermn, ¢ta/, 19t3;

473
9_1/86 Honu_ille. AL

_:z:=.; ,,.__2___:_c_.-_: ___ _

: : ,'.'-4 : _MB_-" _ 1 1'*' I I .ul I I I _ ,

-_- , , , ._- - ,-, • - ? _. .... 7 (b1:19.03:49,.! I ! _-'-'_--I.,.. _-111 I I .- -_-l-t , I

• 7-:-_- ; _ ..... I-- 7"- -" I

--g'_ _ '---_-_--. -_ • "_-t

_11 RAJ_G£

Kes_meer. tt al,. 19_4; ParsOns. at al , ]985), h ev,,)Ivedm an enwronment characterized by low vcmcal w_nd shear _nO moderate _r_-

b,hty, had a I_(eun_l of about 80 m:nu_es, produced L cm s,_ed ha_L.

and mamtamed e refltctJwty core in cxce. of _0 dBZ at the surface,

A number Of m[¢robur_ occur_d _thln ,.he lar_,er scale storm outflov..

One of the key radar-dcceculble pr¢cur_or_ of" the oCCur,

rencc of the rmcroburst Outflow i_ the de, entire& r¢l_ecdv_ty core o( a

coliapstn i chunders(ornn cell (Robe_L_ arid WiLlon. 1984 and 1986).

Th_ evKlence. Lo|ethar ruth the very hllh rain/all rl[¢l ii_ rider

_l_lctWlty le_¢b oblcrvl_ in U_II smrml, has _ n_ny Ww,¢sull_onl

to conclude that liquid w'ater k)aden| must play a primary role _ fortme th_ mtcn_ downward ,,_rt_cal I¢celtrltmn. Arullyt, C_ by Woll_On

tt el. (1985) o( m_lonet data collected durin I the 19&4 FLOWS prolees m Mempl'_l, TN show S_lni_J<ent correJlllon b_tw_len aurl'aCe

reiN'ill, which V_l at Ume4 ex&l_mely hee_f, and th_ su_cneth of

I_ak mlcrot)_lrlt outflow _ (Fil. 10a).

In nearly every case. h0_r, the oudlow corinne was 14In, icindy comer, and had Io_er equivalent polentJal temperature (EFT)

than the suHsce a_ il _s diSl_¢l_l TlUs lnkol_ thet ¢v_Fora_on.

and m _oma delrce m41tm_ mul4 Mq ¢onU_buU_l m d_e helotrY1

buoyanCy. The peak nucrob_rJ_L OutflOw speeds In_ silO stani/icantly

¢Orretl_d _dlh d_l temperature deflck aM the EFT tier, tit o( _ outflow (FiSS. lob and 10c).

Burro_ and O_borne (1986) tnveslivmd the role of pre._ipl.

_Itlon Ioadm$ u_ fOrcin$ 8 mt<;rol_lrl_ 'J_lt oCcu_td durin I FLOWS

1911_ in Memph{I. "IN ulm I aU'CriltS 11_lllUn_ hy_tometeor splkctra.

cloud liquid wirer cOn(_m, and wlruc.al _1o¢_¢y. T'h_y ihow_d (hat in

every pill thro_$h the ItOrm "th_ stron I downdralti wBre found in

ClOSe asio¢lation w_l tM ireas Of I'miW precNPiUIuon toadml', t>ut

the cor_eiauofl bet_en _er_cil velOcKy lind bquKI water content

by no n_im per(cct (Fml 1 |). At thee elaine in the Smrlm (660 m

ill}. (he nlllhve bteoyllIKy contnl_Jtmn from a mlin IKlu_ we&or

content of 6 I_m _ was shlhtly kL_ th.ln that from _ oblmrv_d temperitura deficit of 2.3*C (42% ,il_lter Inad_n I end _8% temperature

def,Cll).

Leech (19115) (n_lkel _ pOlht thai evln If dry air L_ in-

_auled ate the pre¢_plu_;ton core at h_lh I_lll. little evlporatlv¢

C00hn I can occur Since 1h¢ au" _ SO cok'J. In [ac'L el Proctor (1985)

showed w_th r_sulu from a (_--dimrn_onal (Ix._ymm4tric) numcncei

model ol a _hunder_torm, th_ Irml_re[ur¢ cklv_oon in _ downdr_f[

rely actually b¢ politive abovl |he (n_ezin I klvil, amc= the coolinll

(rom [h_ evSporat_on of had _ too smaU to compeRMte for th_ effects

o( comprumstonai haatm I As the corn descends, tl_ effecul o1"

evapo_.v_ cOohn& become much mor_ _mponan[; three effect_ roll

be moS( ,mpor_m near tM klv¢l o! the minimum m _lUivak_m pOtenuai _ml_lraturt As SnvasQl_ (19115) has noted, when a $iv_n water

mu_n I raUO I _s completely ev-,porlted, it _ contribuul roulhly 101

IO the nelatlv,I buoyar<y thro_lh the re|uhlnl tcmplralure delri¢tt,

At upper levels in the ra$1on Of hquld and/or fro;'in water

accumulitmn, _c_p_tauon loidm I i the dom._nl Mrcm I mechanism _n mmaunl the _he coHap_4 of the c©ll Ho,,_v_r. coolinl due to

-a[=r phl_e chanle$ durra I [he deitent ol lhe core must plly a $1lndicam eol_ m the addn_nal forcm¢ that lives r,s_ to the cx[raordinary

outfluu speeds Of the few cells that p_oduce m_¢robu_14 (l_e 5mnh

and WiranluskaS (1985) for e_amples O( vmually impressJ_,e

mlcrubur_'_, w_th reflecllwty _veb over 60 dBZ, that ptod_:ad Only

20 km po- _n.

_,e_k uutfIo'_). Thui. the r_lture of tl_e entflinlneflt process Of de)' all

_n_o d_e dow-ndrait is of Ireat interest. It should be noted that Iq;mf,-

can( evaporation may take place whhout Ihenn$ tha Sel_ral i_eraf_cc Q( the radar C(:hO. The Inll_llelt dropi wdl evlpOrltl li_t lind

rP,o$[ efficiently, but el'HI)' contrl_le relJl_ly little to the r_l_llCU_t)4

which _ propoft_orul! tO the I_th power O[ thl rain drop diameter

Al_O. 0"_ reduce*on in IKluid water content auo¢la|ed with a feeuction

(n radar rellectivitf ol $ dBZ from _$ to _0 dllZ ii almost 6 urals as

great as the reducuon ir, Iquid wamr contaflt esso¢-,uld _ i $ dlZ

reduction {ram 40 to 35 dBZ.

In summary, d_ air mass I,hunderltorma w_th the str0nsest

collapIln I phase dow_drl[ll arid s_d_lqu_ni outno_u quah/y el

m_POb_JnU. In ese_ntMllJy every case, _ry hel_y rlJn_3]I ¢oncenM'll¢'d

_n an area of small horizOn_ll e_IN., end larll_ decmala in I_lh mmper_ture end cqul_lent pomn_al tem_nlture at _h4 _urfl_e are eb-

_rve, d Often (he convection from_h m¢l_u_U ar,l_ts_K

init_ted by the conmrleo<e l! th_ _ ol older oudiovl, 14 the

m_crobu_t surface flow l_tlrm {I o_ln emtxld4hKI In i ilql_r lk'Jk_

35. IIII

30'

TOTAL 25.

RAIN (ram) 20-

15"

I0-

0

Fi$ lOa Tmal

IO'

8"

IATI 6.

(-c)

• I1=_ u , __ • ._ :

_o 1.5 20 25 30 35

PEAK WIND SPEED (m/s)

ram vs. p_ak wind speed in Memphis mtcrobursti.

• A

4. _• AA && A

2.

PEAK W]ND SPEED troiS)

Fill tub Temp. drop vs. F_ak wind _oced _n Memphi_ miCro_,_/s.

25 " •

I_ EPTI 20

(K) I'] • •

I .I * ee •

0 S I0 15 20 25 30 ._5

PEAK WIND SPEED (mt_l

474

ORIGINAL PAGE ltSl

01_, I_OOR QUALITY
|

t

m w w

n_( (lK_m,mD

_J_La$ I_ 16.4_kt$_ E_Q_SS

__ FOOR QUALIT_

form later ,n _¢ "¢halo" _l_eSr to Imw I-aamr end tal_.r. I_rhal_

b_caul_ mot_ humid air is antrlmed rata their u_drlha aUowl_ 8 for

lc_a diluted cores. Them downdmrtL and OUd_O_l 114)11_1 ¢Orrei_ndm|ly Lu'onl_r , peovk_in I more fOT¢ln| for the next cell. ,lind 8o on, To

lhe cx_efl¢ that _ muhicen Itorml ire _-rler end Io_r U,_d _an

molat_d r,torl_l, Lh_y are easier for air trllifl¢ to at_id; ho_ver their

explosive growth mlkel b'_m wry unpredl¢t&bl¢ ind aitlpece U_I

was _ safe d_mnce aw_y (ram such a _torm complex one minute could

Ix 0nundated whh mLcrobunl| w_nd ihelr the next.

The microb_n_ that erase from ihatlow, hRh-bnfcd c_Jmulo-

_mbu_ clo_d$ can only occur m an env_ronmem with a deep, dry

adiabatic _,x_d blyer, w_t.h $_fft¢icm fltoil_tUYo aloft tO i_t,lin a

downdreIt all the w_y tO the surface _n the face of iI_r_ evel>Oratmn.

Su_tl_b_ cond_,tionJ_ M_ mealy been oblervIKI in th_ high piling e_st

of the Rocky Mms. d_rbl the lummer mo_, The luffece raflec-

_w_ty velUes Of thnlie mictob_rl_ af_ lOW _nd, becauIi! they occur in

an urban (high C|uttlt level) en_rOnment, a OOpl:_r radar w_th soph,Lt)cat©d ground clutter _upression capability is t_quired for the,r

effectwe dct©ctlOn.

F:& I I, VertiCal ¢e_OC,y (Solid line) a_d preCip,mtOn weZ_¢r

contem fda$_td lint.) at# plo, ed /or one po_ ;hrouEh the microburs1 #tocm On I0 4_&url J985 In Memphis, TN Aircraft _llltud¢

_,,a._ 0.66 tm a_l From Bu,ro*_ and O;borne (1986).

s_arm outflow T'hu_, the convection ._ often but not always in the

form Of multiC¢ll _tOtmS, both "Secondary" or disc_tely propegat_n&

a_ deathbed a_ove, ar Ioosly orgenltcd wlth clOser cell ipacunl m •

hne S_,orF_ w_th Ove_hootin$ _op_ have grelter energy _,,v_lS th_n

o_her stot_, and their cores contain more {ca which c&R Iced to

_rceter [enerauon of n¢|atlve buoyancy a_ _he downdre|t_ paas

thrOui_h the freezin I [evel. Vortices St the |eedln_ edge _nd withe the

mlcrobunt ouU_ow commonly occur anO ira a_oc_ated wuh v_ W

stron& s_rfice wade

A_rcTaft accKIcms attributed to nllcrob_Jr_ wfild shear and accompanied by very hcav_/ rain have Iced to the $reateSt number of

fs_litieS. The rain _n Some ca_es has bean _0 heavy that it has been

sul_estrd chat the eer0dynemL¢ parf0rm_litCe Of the aircraft deler/o-

_ates be¢,a_ of it. resul(h_ m an overall _ O( li[t (Luen_ and

Hem&S, 1981; Dunham cr el., 19g_; Hlrtsman and Crawl, 19_7).

McCarthy ¢_ at. (1979) inveltqLamd the ,ale"Cilia n_apofll¢ to d1¢ EJIslern 66 mLcrobu_t ,lit JFK, and found d_t the wind shear speCUlum

con(lined h_lh ¢flerly ,lit _ sin:ella's "phulok_" or r_onant frlquency They behave that _ r_Donance sarloutly de_r_reted a_rtmft I_f_r11_nce by IivU_ n$4 tO suCk_ln o_cllln(_om In a_ni_d and

hni|ht at)out the |hde_lope. 0b_u_ly. d_e high rate O( O¢¢urr_it¢_ of

a_rmass _torfl_, the{¢ highly diver|erda aud[ow% ,lind the emil. inli Ind_¢ant-IOo_ s"a Of the cel_ from wh_h the mkroi_tlc_ form eli

add tO the I,_ellon haeaed

J. _UMMARY

Throu|h the precede| review, it has been impIMd but not

proven that a number of dynamically duun<t phenometw |lye ru_ tO

strong surface OU_ows. A( th_ L_r$_ s¢nkns, (hc or_lnixed dovml_RI

s¢orm.s Occur [11 isao¢tatlon wlch melo_ale or Iimo{IR_ scale lineer

radar ech0 ¢orffiluraoom, in anv&0nmenll charac_ltlt_d by modnnlte

vertical wad sheer_ and slronl[ thundemorm po(en_l. The Ilren¢_h

o( the ablated Oud]_w ts the r¢iuJt o( bOth the su_th of the venkai

veloeJty and the downward flu._ Of hon¢ontal momentum, and rrBy

abo be influenced by the nearly (wo-dimcru_onaL lirmar stOrm EeomeU-y. 0_cau_ these storms are tar_ Lca_, Ion$-_ed, mfmqucnt,

and _evera. aircraft h_l I_rgaly been vectored away from them Sac,

tess fully.

In envtr0nmen_ w_lh h¢0e wind shear, and slmlbr co,Klit_onal lr_lalbd_ty, _lo_ated lit nl_l thundentorn_ form. lit w_rnn, hum,0 condit0orB the strength of the Ou_ow from these s4orTnl _, determined by evapOrative coollnll, both in cloud end below cloud bnMm,

and by pracip,UHi0n 10Idle 1, especially a( upper laveD,, AS the OUdlow

pool rapKlly expands, even I Itra_ht-lJrte m_robtJtll _ f0rm m

assoC_,ltion w_th the Leadir41 edl_ vO-"_x rOU. Thil ty_e O( nucrol_lltproducmg Itorm has proven to be the m0_t heMrd0ul for av_UOn (or

a numher of rea_om: the frequency w_h which they O¢¢u_, the rapid.

Lty w_h whKh they develop, thmr _wU lenin, the _et t stronl OudiowS

that they profile. |heu lick el Irln_lldanll motiOn. ,lind also the fact

that ltor_ ldenucel in appe'arsnte, at Mast v_lually ,lind oil conwln.

tlonal a#rcraft radlr, era su<cemfully flown ttu'0u|h On • regular I_s_.

in between, to verym| de|reel, other Iorml of loosly organ.

n_ed mu|ticell storms lOre It u_ pod*hie H_It d_sc $tOrnnui. with ¢lolely

,paced echoes thai merge to form I spearhead appearance on low

regulul.on radar scopes, are $;mdar 10 the microbu_t lines [ound near

Dense: however, they form w_thout any orographK orJ_mln0on.

Strong Iorcmg O| the updrah CaP occur iS the outflow (tOm a nearby

d_:ay#r_ cell tnMerl the enhanced Srowth of n_w celil. Cells thai

ACKNOWLEDGEMENTS

The aulhor wishes tO thank Dr. T T Pupal (or/_umetou.s enh;htenm_

d:scusi_ons about microbum_. Dr K.A. Ernanuel and Dr. JE Swam

for their con_cructive commen_, and J. Cullan tar h_ help compiling

the P,.(emph_s microbur_t surface character_ltics.

REFERENCES

Aerial|on. J.R . KS, Dmellemeit. and k I_. _llhehlllen, 11_|5: Simulllmfl of

_he _honde_tolm su_kP ''4 Ifl_tlO_n_h_ Pcf_lq_l. fnlk Co_._erlmce O_ _e"

¥*rf _¢el $1otm$, IMll_ee_olk, Amet, Me,or. $O¢.. 14_-I30.

Bedanl. A J.. Jr., nd T.J. L_FIbm. lY16: $U/[ic¢ meuu_ments of lal f;OeM

end ml¢eob*JtlLi 4urtrt_ Ihe JAWS propel*. Sl_lJllNIJ /elVl_l aM ImplJeallo_l

|or wind lltee_ d_tn_n, pteakt_, id Medel_lll. blOAb4 Teca Meme

F_AL-WPL-tJ$. Wsv_ Pt_p_l_¢lon (._kefy, I_'Mef. ell _p.

arihem. R R., Jr,, |95_: _ w•l_r end eMq_lf b_tll e( _ thgl_k_l_totm end

their telllk_fl to thuMIrllorltt de_loIhlleah J. M¢IOer., _, ;J6.

9tiMeS. E.A,. 197?: Flow _ _e_m tavndeRl@tll_ &teem4 by duil-Ooppkr

fader. MOil, Wee. Re_., I0_, 11)-!20.

Beown. J.M.. K.&. Kflupp, eM I_. CAta¢l,_a. |_$2: _ltnmtlw wth0t _rom s/_ltOw, h_$h-b_@44 cumMMc_ndDI, Pr_ptletr. /_la Cam,{¢etnot On tier• _,_ce/

_lO_ml, Sin AntohM. A_F. Met&el, _¢,, 273-_7|.

Bwrows, D.A., nnd L,F. O_beme, IIlM: rn_lldlllk_n loed_ m w_

mlcmb_nlLi. P_'ptints. _J_ CenlV*_nce en Reder MetteNdajB. ShOals.

Ama_, Metier. Ym¢.. Jg3-lt00.

P._fll. bl._., Im_ P_.R. I_tab_J. Jr., t_ag_ Tka Tkvndtrl_erm. U.$. DeF_rlm¢¢l

af Cerumen. Weshh,.K_. D_. _NlY I_.

Camid_U, S.O., till: Mkc_l_l_ll plumier n_ca61_Uelt _$ 4n eallen _rs_t_

sppreeih P_epri_tl. el,it Inte_etlenei Cry,ferret# a_ Plte_¢,l_t In/errorliOn e_# PrecerM_ I Sylre/i lot AdetlOf_to O, OceeaO_e_lt_. inQ H_ttel.

o_D'. Anaheim, AR_lr. MII_,r. ,_N;.

Cst_Ceq&, F.. |93|: A _omp_t_oe of two d@Wob_?ltJ OI _ff|elllht _ Dart-s.

P, el_lner, Center•non on W_e_k_r leOeSc_UM$ emd A_ely_$ end A,_erl¢_

M¢reotwlol_, Sibqt _pl_lll, Ame/, M•leOt. _le,, ||)-_0.

Cst•cel_, F.. aM M, Meier, lfTl: Aealysll eli mklgiluNt bl iM FACE Meleoldie,flail mmmt_(wtIL PrepFmas, ilia CsR/eree#$ Sn Se_e¢ IJeel $tormL

Ks_sts City. Areal. Mef_ol. S_,. 279-]86.

. Caf•gens, F., R.A. MeMGX, J.FIW. _M_m, l.F, Wee,_T, mini R.N. Gmn,

1$1131: MulJl-S¢nie •fleWlil e[ mekrol_l_akll coRe|tire affl¢tlea PIn Am

WorLd A]rwnyl Fll/h! 75_. N0.4.4 T*¢_. Memo. £RL-EJrG-I. Entvfron_nbll

C•,•c*l_d,. F.. J. McCarthy. tM J.A, FkX¢t. tglSb: Vefatl_t, tllq| film ||MIboe4 0|

micml_letl lion 11114 fmnl taNp o( Cobrede. J_'e_ti, l Jill C$_[ere_ce o4

Sdn_'¢ LoNI $tormj. Tulsa. Aflt_r. Meleof. ,_¢., $61-I16s.

C•r_4_eM, F, R. On_. •nd J, Aullul_e, 11116: The c.ul& el Oell_ Flllltt 191 Ill

Dal].ll|-FOrt _V0ttE IRtotmmtloIMl) AJrll_rl On _ Aue_t )tie.* MulUlesie •fitlyCool_ I, J,K.. 1!1S6: MKmbunl_ eL Hickory Corneal. MlChlgee. _l_dn_. _Jrd

Coe/eren¢_ on Radar Meree_olo/,[_. Sl_OWl_u. Amer. Meleer ._¢.,

Jll3-Jl|$.

Die,lena, J D., 1913: AMlynm el • P'unden_tm dowflt_JlSl, $.M, TbelM. De"

p_tln_nl of Me_o_lol9 Id Vl_!_.C&( Otes_pky, Mi_Sthat_H tn_s_-

lUle 0[ TecbnOloly, I|0 pp.

L)odle. J., J. AmoM. O. WiL_on, J EvaM. lad 1", /ru_lm. 1906. The c_o_.rxl,w

Huntivlll4 tl_eOl_iOS14al ¢•_ers/l*l_R¢ (COHMI_X), _utl. Amte M¢le@r.

$_c., ST, _1)-*11,

Du.Mm, R.E.G.M Keyes. C.L C_nlry, aM _,. MeMel_. It$$: T*o4im_nllen•l wt_d I_Mel totla M a uaM_e¢loty_l aif(nU i_ e _a_er Ipmy,

41AA-IJ-OIJa

Dyer. R.M., M.J. Km_. •nd J.F Motria_y, 191#: D_Pi_r •_¢valloe of

Aulmt_l•il _iB/llona 0( Aua_ll 12. 197J. P_p_ntr, I?ta Co_/err_¢e a_

_e#e# M,feo_elo O, ._llbe. /1,.me.. Meteor. St.. 140-1a3.

EUU, M.D., eM R,J. _ovM.k. 1¢$7: Okl_hom 4_vmt_f_U eM tN|r luWmm_tly.

.I Ctt_ete A#_I. M#¢ecr.. l&, If.71.

ISlam. K.L,. t91a: E_)tul;ofl e[ • t_cmll_lt IM I_"Sl_l_l ecM dvrms

JAWS. Ptept/_l. 2Jra Ce_/eNR_ sn Nan_l M#¢alm_let3, $M,,,m_lt.

Amet. Mel,_¢, Set.. JlOl-Jt04

£_,_m. J.E.. t,_l D. Johann. Itli4: The FAA _a_llefttldl 0eplSiee _•_lwv

f•eet. P,f_wint#. _2md Ce_er#,_ce _ Redse Mete*rel$101, ZurHk, Anwl

Fv•fl_. J.E.. ine D.II. Twnbuil. lel_. TM FAA-MIT Lllle_M I._bet•_ry C_,ep)et w•lll_t t•4•tpt@at•ra Peef_n_ll. _nlr fleflr#411eRJtl _@R/d#¢RCf _ I_e

A_•l*O'l Wentnvr _ltfm, Mo,nlmet, A_v. MS_;. $_,, Y'6-7_.

F•vd_h, I_.|., n_ It,. C. Millet, Jr|4. & 8_Sli |er (emeeitie& Imek wtM I_-_

ie _)n-fIon(•l Jhunderilo_. _vlf 4mr_ /_eteer. $¢¢.. _[|. la-1t.

475
For_l, _ | . M / _altUl. IidO O. L_aallni. 1910 _INill iyliOplk lld fill|l-

|tie _¢_)tt _l¢lltld imi del_mt.lv_ot_In I thut_llln_ml. P_lmlltm.

It& C#l_rrAuot it1 _tat&#e Ftw_ltlm_ a_d A_dlT_t. Dill_lt, Allll. Me"

Fod_. O S. ISd R M W•_hi. It15: A ¢oMenwlml omb_ak ef Iomid4_e.

6ot'_llmn_ =M mk_I. _mll Igil0_tdo_ mllti_ql vtr_ex ¢ILU11_lati--_.

Mo_ W,e. Re.. tlt. 120-235,

FOIler. D v_ . 1#_ll "l'_IP_llli_rwt pllll ¢of_panld w_lh ¢omll_ItO_ll doti_fl_l

ipm_k Men Wee, ge_.. el, 91-14.

_JJi T T . I_76 SJl_f_Sd _N;h_Oil_ dOl_fll_dPli /Igif Ibl iI_S_ e_ of •

_ohn P Kenlil_y tUlmr_ n_l_¢iy, P4¢. York CIly. _P R(# Pip. 177.

_nlv¢llH 7 ol _llealp, Ill.. _1| pp,

£,_,li T T . 197i Maa=l of d_wwb_Jrll k_nlltb:all_fl for pl_}@Sl NIMROD.

_MRP Re,r Pe_. _$L, UIII_DFIIIy OI Ch_¢lll_. Ill. 104 _.

_'_;Lll. T T . 1971: O_k_[h_l. OllmtlOll. and _llui= 01 Propel NIMROD.

_e_lll_t|. I_li CO_/[era_l_f #_ Serif L4_cal _rorm_. Kinl&s Cily, A_y. Meteor ._¢. Z_9-266

F=pIa. TT . i980: Dow_i |_J m_mbu_u - an =vlit0On hil•nl P_rper_,.

| Ilh CO_ll_I_¢l On Rsdar _ad#o¢olo_. M_a_l _lllch. Al_4f. Mallet. _o¢,.

94-101. "

Fu]iuI. 1" T , l_l)i; M_¢lOhltt_ LI &R I_11|_ lirl_ I_lll P_IZi_4 _O¢_#dix I]

o[ |_l /gt_l A#r##NI¢i 3crew|it Mce¢inl. 51 t,._fl. AI_A=81_0386, 9 I_l,

F_tl T T . 1911b. T0r_d¢_l afNI dowhburltl I_ th_ conioxl el lah|ri]lll_

plal_etllP_ 161_i. J ArmoR. SO . _1, |511-I.f34

F_f*li T T lgl]: _41¢/O_Pl| wilt4 I_lf tt NIl Oe_lt_ Ih_rns_o_ll A_rpor|.

Ke,_<f LouMMnl on /ulv f d I 91 _ . SMRP R#_ _ep 799. UniverltiyofChl-

¢110 IU . )9 pp

F_I_ti. T T . 1914; A_pIw_ AF_ _g_Uglt _'_ r_lao_| II|or th_ tOUgMowfl of

A. Forge 0_. $MRP Rtl Pap _0_. L._Nt_rs/ty 01 ChiclllO. 111. _B pp.

F_}tt& _ T . I_ The _OWnb_¢#l * M(cfoh"rl| I_d _aCrO_L_P#t. Sa_llI_! tl_d

Melom_leOrOL_ly P_oFcl. l_ri_lrlmenl 0f Ihe Goophys_:ll SconceS. The UhJ-

_e_l||y of Chl¢llo. Ill.. 122 pe.

Fuj_ll _ T . ]911' D_ M_c_PDk_'M 5=l¢liJlf and Mesonlll¢OrO_ly P_0te¢|.

Oepll_eRI O( tit4 _phyl_lJ S¢_et. Th_ Uniytf_tl_ Of C_sIO. 1_1 . _ _4

PP

Fuptl. T T . IM H R ]_}_t_l. 191_ _pif_a_ K_o IM _oi._P_Jrt| i_ I_ |fish

or /in Iltl_Mf ._dtQ" I_fll _l_a... tO_. ]39-146

FuHIi 'r.T . IR_ F Cltl_lrml. 1977: All aflllystl of three _II_p_I_IIII_ lit"

crl_ ic{_litl Rule Amer Meteor. $Oc ]|. 1164-q Ill.

F_IiLa. TT , end A M Waglmolo. ]981 Five lairs Of II_RoW IMO¢II_G w/Ib •

i¢tlll ol doinb_rl_l In I6 _ly 1910. Mo_ WIa Rio. 109. 1431-1411.

Doppler tldlt. *lrcrl_. I_l rAM till IPrep_lilt. /Jilt Co+l/tttPIc# On _tt_rt

Lnelll _lorml. TuII8. A_IWT. M¢IION)r SO_.. 97-|00

F_j_ta. T,T. an4 g M wal_/mote, IIllt: MK_ok_rl_l in _AWS _pM_d by

{_pplef tldaz_. PAM. 8_1 let+al Idlolol_pJu. P_rp'lit# 2JI/ Co_/_Fe_ 1_

Radar Mcteo_o(<llr _. P.d_rtul_. _r. Mal_o£ So_. ti)l-64J.

Golf, RE.. If10: L_w-L4wi Wild SIl_l! Aklrl S_llem {L_w_AS). FOAAD-10-L$. Ft'_a_l A',_.dO_ Adm_lUltTstl_n. Wash_l._a. DC. 11LO pp.

Gee|a•. It.A.. 1979: A/_re_ den_cthia if lo_-le_.il _ Ibesr../. A_¢_',,_. 16.

8=$-1_?

HIINUMli. I_, F . If?0: Usl O( tetilt'd Illloilly flair d4[l In m4104¢all iurfi¢¢

• mil_li of Ill July 4 1969 lWfm hi Oldie. Predict#. lit* Con/i_ce an

_dOar _tft_rolo0. Tucion. Am_l. Mitt'or S_¢ . })9-346.

Hsm_h. R.J.. If.. 81'xJ A. Chilli, 1917: Low Reyrlolds numl_r llitll of NACA

14-210. MACA 001] slid _/OlIlIIIM FRIg-KI?0 *|_o111 m rain. 0. _Jrc_@.

14. $$9-$64.

He.vmdlrNId. A.J.. D.N. ]ohMOa. _ J.E Dye. 19_8: Ol_lrvlklmndl O{ mai'l

4d_1_4|_4 Bltll hi _rlMll| P_Ol_rldo ¢ldmulm ¢onleit_l ¢_udi. J. _mol.

$o , 3|, 1619-1703.

HmrKl_l. G,. illl: TOPP_dOII Id deNibo+ 4mtr Merle, J.. $, 301-}17.

341 -)49

l(_{mklJt. M.A.. 1984: _4lr al IUJ_ICI Jill tl_l_l_l Of • r_J_PO_lll

Me_r. So(.. 64-09,

fl]elmlell. M.R _M R.D Ro_ru. 1985: Micm_rll )ine_. rrr_im_#. /,lt_

£e_,fere.¢_ ;,¢ 3"r.r_ L+¢an $_rm#, I_d;+'MpOt _'. Am¢,. Mll_0r SO+..

:9_-_00.

HjeJ_¢Jl. M._.. R._). _rll. and H.D. Draftee. 1916: ObNrvi¢_oil IRd num_rilil Study Of a m_l'e_l _M-p_4_/i I isl_tm. PelJwfn|... 2Jtd C_/_r*

tore oi _dd41t _¢t#O_ldir !, _ll_lq_JII. A_T. Malaer. _N.. ]7"1-J10.

3oNP.J.R.H. and W.D Haft. 191_' TIll dl/_llxL. A li_lll wla|kl_p_<_l_|_l

cah_l¢li_l lyltlm. Prl_/Rrl. l_gh _o_pr_l¢e o, _t_r* _CGl_tO#mJ.

Tuba. /_ner. Mllaar. 509. I71.111.

Ketsm/_t C J . Mi_ H_N_, IM IW WP_I_ |_13 L_t-i_l flIKTlb_ri_

wrt_d lln_Cl_N ullll I {)Spirit radar Jill /'AM d_l_l prowl|#. Z/l| Co4fer-

#_¢l Oil _ltlr Mefearol•l_. Irdly_Moa. AR_II Metal _4 , _-615,

ge,tnl_r. C J.. I.W, WIl_ll. M. Well--m, lied# Kllm F, 1984. T_I I_bl_l_

of _MOt¢ale ¢iNlule¢lOk m I 4ewnbull|*VIrodu¢_n / I_Of_ I_ ¢0fl_plrleo_ Io

_lmln¢ll tlllull¢. PrI_R#I. l_fld Co_[¢reqce a,i Ileda_ M¢teo_lod_l.

Zu_glL Amcr Mewof So< . 38-63.

/erll.ce ota Rddar MtteerO|o_. $1_wm=ll. Al_a_ Maul.at So< . JIO$-_I0l.

KcITN_. _, 1111: Wd Iklir iN •_a_l_ mif, ly, Narir#, 31S. ITW-IIO.

p4tCql II I_arll_Pl_. J. AHqil Set . 40, }Jl-]_?.

KIlupp. K.II... &l_ W.[. Clltt@li. 1_1_1: Olili_ _fltt_ilhill wtlbi¢i _l¢Lp_ I

¢OIt*./1_11_I_ ei0_dl _ip, Otl. lark EO_era, Cl *. _#l.e_e l._lll $10t_l. |INIIl.lkIp_l. _1111. Mill•iv. $O¢.. 111-|74.

Knupp. g R.. Ind _'.R. C_II_II. tlJ$1b: COll_Ntlw ¢M dliwndrlft l(irloglurl:

Knvpp. K,J . aM _)P Jd_Fmlarl. 198$: CIN Iludy Snltyl_ el I LstOS-J441e

_re _4ral $_k'mt, IfMblllipolll. Amar Met_ex _ 1 . _QI-)04

_r_lllf, _.g-, IINI _ M. Wilim_lo. 1915. NV_d<lI Ijrsul4l_on at dq

J. A_wr M¢_ler S_ . 163-166

[_u¢_lr. $ I(.. ILM _Vlk_il, tr_ SJ. L_J, 1916 11_(4t o( _¢¢-IN_ml_

_Klaph_'lKI i11 dR ml4_oll_lt_l luvlult|lorlal _re_e#_tl, 3]td {'o_t_#e OA

kf_mm. _v It 1_1_4 ON Iblt C&ull cll _lRdrll_ r_ dry lhuP_lrltotm.l o_r

1:2-t=_1

L_l,d. I.o. =_LI J.l_. 8_m, Ill|: PAA _,_qltll_ Iw_lil m L_lgngll_l i

zl_ cllnllx_ of NIIXPJ_D. I_'r Repeal ATC-I I,_. MiYliJIIIIOl _lll_l W

FA.A bporl Ne. F_bl-it_.ll-lll. III alp.

L_eci. M._.. 1t81: O_ tie _lil el IImPl_dy_llmll I_l_le el NmN d•wlllllfll,

Monml4L Amid. Morner. S_c.. _04-]0t

Ll_de_. PF.. iM J I. _LipsOll. InJ: Ml(fl)_u_lt: • bl¢l llr ii_llh el-

_.e¢. )tT, _1oIO1.

Luen. J.K.. _ P. HIII_I. 1911: XtlVy rail wllld IJINf I¢¢MIilii. _r#l_lltt.

A_. Miriam. 14<.. _-1_9

Mlho_¢y. _V. p • I||. 1913: "I_ lellhipr_e0! og dowlMm/_l fm_ll tM tYlpe/l|ll_

OI hy_f_r_e|eOPI. R#pOtt #d. A._'[4d. UnlYlPIJt_ Df W_0_dftl. I-t&_. 146

pp.

McCirfhy. J.. _F. Bl_k. IM R R. Bemch, 1t_9: .lilt trl_4_tl _r|•/_l Aa

IhMr_etllOt_ w_h_ I_lr cOMIIIIl_. #A_A EoRital_]dll. Jl_l_rl $_07 bar.

Ihlll _pl[¢l Flesh0 C.e_l_t. HunUvtUi. $_ p_.

M¢Cl_|hy. J.. }.W, WIlloW. I1_! T T. F_. 1|1_: TM #Dim AIt_O_l WlltMf

S_dies Pl_|e¢l. _ull, Am•r, M#teol' _rec.. 63. 1_22.

k(cCar|hy. J., R,D. I_lttl. a_4J W E. _l_tJ(_r, 1913:JAW3 data cellee|len.

i_,_lyILt htlhlll_, and mi41_hur¢l ¢lltbt_4. It_Iprhi_l. ]19 Co_Jr_#e*ce e_

Rdd_lr Mr_¢#roro_. Rdn_nm_. Ame_ Me_lr 14¢.. SN_01.

Me.#s|. M "_V, 19I_: A_on_Ivld dlli¢|io_ a( Mm_ll _lillmaf |OI TtlmkMI

E)_ppk:r _eil_r _a_lr. prapGiacJ. _tli Imoff P_4_t_ I aald Vllill

CGmml¢_ll¢_|lOIs# TllakllOtO_el IFI M_lltPol,i_. _illlil_ll , MJ_. S_1£

M_.+l_t. C.K. ind P.H. HIId#l_lnd. 1985: |vlhill_on o| _ltel_l_ll iJrroof Ocee_t< T#¢_ol., 2. ]11-592.

_a(,o_ll Re_=aT|h Count||, 1913 _w-dlrr(ud_ wind #_¢4_ #',it I/I kdtard I_

_r_on NiLhina| A¢adtmy PePsi. TI_ pp.

I_'ol|n_R H , 1959: A radst IpOllll:n auO|M|ad wilh IO|nsd_es _ull Amae Me-

, So<, 40. 277-_?q.

[*_nllM. D.B.. C.J ICesslltl_r. K L. Eb_o_. •lsd R D. I_blrm. ItlJ: An ia-

.est_f_|_n into Ih_ fo_¢_ltl Of mKm_utlU. Pr_lltf/l_l. 14|h CQ_l.fercn¢C d_ _I'¢-

• ¢,# bocat _Oree_. Ind_oipol_. A_t. Meier SIC.. 41-J[-

P_¢P-on E C , ]ga5 'lA_k_ mkl•i_rlil O_¢Ul_nll {l•_l omlRildh_¢ _N}I

IIr_ls pr¢_ers. 14rh Collier|ace o_ $¢_¢re I.ONNII _leeml. ll_OleRi_•_l.

P_o¢lor. P.H.. 1915: N_r_•l Ilnlld4ifOII •f pl_gl_i_llill iltldlld dll_l_Rll

P_l_f}_t_. _ld /_taPRIIIIRt/ Cll#P#n¢l Bill I_1 AlddlIN _#l#k|r _llla_l.

MontPlil. A_n_l. MeMOr. |OIL+ 2|?-2114.

Prly_/ll_llki. R.*'l_ . arid _._. Cil_/. t_13: Tlll tll_ll_lly M II_ _m eah_ &l lln

Jmpolllll| Ii_lr_ _ll_ll IJI_MIIMM. _¢_i_tl. /#1_ CORf#FI_¢/ ON _¢Wct L41*

PtgyUTtm_kl ' Itw.. •M D.M. l:_Calm. 1111: ILIdllr IdllMNms aNI41111d wlsll

Rly. p.l:. 1971: TflpiI-Dop_lt oburvllk_l I_ • Soll_Ntl_l III1_. J. Ap_

I_ll#Or.. 1J. I?g-190.

ItOb+ru. It.D . lln4 LW. Will_n. 11114: PstlNV_'_'II Illd leJImllllt_l I_l_pl II

o/aEr. Z_lrgh. A_lr. M•l_t. I0¢., 71-76.

I_¢ Doppler r6d_r dltlA. Pr¢_l#, 35_ C•_n_ e_ RId4¢ t_¢rl_relo_.

Rodl. A It.. K.L. IL_ot_. a"+ W.p. M-_._y. I!1): AJ_mh 114 g_dat e_

mollon I_mwIrtlOFil in • _IAY_I m_NIUImlt. Prd_li. |IM CoplJ_alt_t e_l

Radar M¢_#Or071_. _dmnUs_. An_r. M41_r. _,4_., |]4-1_lf.

P._l. A.R.P.M l_m_. ind K.M. _mUllel. 1tl4,: Akmmlltill_onl •1

d_wndr•ft formallOa b7 a_tll_mUOll tM alN M •( h_i_n, pr¢_41.,

_.Ird Co_/tr#nca o# R•d•_ Matt¢_OioO, $1_wma,u, A_l_. M¢leet. lea..

J73-_96.

_¢hmd|. }. M. and W.A. Coalo_. IllS: _•w ecM IIR_li_ _ld •vOIINkHI I_thJll

.S_o_m#. Ima_l_l_OLm..•411¢r. Mei_ot. SIc.. ??-I0.

_mi_h. DE.. t_d _.K. WamhliUIl[ss. I_]: Amll_ll_ OI _t IMIllb_ltl ItT dell

r)0p_kt iml IPOlmd ph4k_vmpb _, P_plm¢. IJIA COat, lift I_ $_e¢ I'(II

Sn_l|h, S E. aM J_. _1111Cl. |liRa IOw-_h_ IROhi44NI ilrlll4_ •1M_INIIJ_Itl

OIt _6 _p_I 1114 Prqr_wl_,|#. _41k COn#t*al_ _ $¢HN _gll lll_P_#. |MR"

Srivilll vl, It C. , ltlJ: A I_Y_I I1_1 O( i_lpONl_lly dl_l _l_; AIIpll*

(*tion _0 a nuc¢Ob_U_t dov,_lr*lL J Acmctr. Jr4_,. •$, 1004-102_.

$_¢,tmmn. L . 1914; _derltOrm _'_¢t on {)tll_l_ ab t/lll/le comlel Ol_mtIOl_l s_d _ role of N_VJKAD. _T-T_rC.IlJrPA-Ihr.I.U.I, I_lllilltmeltl •(

Tr&nlpoINllion. Walhliltofl. IX:. 91pp.

eraL_l_ll _lw_Ofiml. DOT-FAJ4 -PM*¢_I. U%S. _plllma'l I_ Tmmpm_la.

Wa_P_OlO. RM. 111_; Thl U(a lY<le of 4 I.hlmd•_ll_nu IWlt flel_ al VN_Ni

wl_h DOppler el¢•y 8nd _lvdm_oM+ _a_l MIn. Wee. I1_ . t|4. tO_1o1011.

_&k J_lo . _ . M . I 191_: P0=_'.li|hi| dr/ mkt_tll agllVlO_ IRe IPdt _ pIlINt

_. Wet Re• . II). I1_1-1|_.

_'lfinl_lkal. _i. It . 1_1_; TM tOUr _I_NIII.* A DIe Ilplllll_ll _ i_lll

IWllk d_l/_tlSI, Prf_tRII. Idrh _'_,,e_ecd_ $. SleIFl _ilf St4k_lil, liMit•ItWe4m_sn. M L. J.i_. Klemp. slid J.W. _n. Itl): DyMmll _e,Rlillln _

P.e_wr,|l. ZlLt COR_rlR|d Oa IldlV _I_##WOJI_P. IldlllOIINlll. If. MIP

_or+ 3o¢,, $t-43.

Wmo_..LW. R.D. bbe_. C. KelelNpr, *ld J. McCIRIIIh 118•" Mkmlil_0

_(nd ttr_ur_ a_ e_ll_¢G-I el I_llil_ rsdl¢ _Ir skl_n _ _bs_ 4ewe.

m_ J C_Jma_r _. M,-_p- , 13. I_l-I|_.

_._Mn. I W . aM W.I. S41v_ll_t. 1116: Im_mton el' ce_mllW Imml av r,-

d_n-a_l_rv_l Uili46ry llWr ¢lllhwl'_ln_lql ll_l. MINI. Wel _lel. 114

t$16-25}1.

%V_lf_ln. M M . 191_" _pqllt t•daf olPM_lll_lla I( li OII)ahtllldl ttwld_lll.

,,_ S_x . _90-$_/$ end |.M Thes_l, Del_¢SmeM It I,i_l_Pmhily I_,d

O_laa,.mlllpk?, M414N41¢hilllll IRIllltlll OI TI,II_I_. 91 lqlWo0f_em. M M. J.T Oisk0r'm. snd T T Pujlle. 19&$: L4w-a_vdl w_

$_it ahlfa¢l_lkll il IIII Mir_ph_. TN irll I_lNd lti I_ll_Mt Inl

[..L_VAS dlttl. _pr_mll. IJl• Cg_lJstsqc# OI ST_FI# _.dWIII Stllo_li. II_lUl&,

Z_rpel_. G. I¢11 Tkl m_lhi I m[IoNrll. I[[[ ,t_lle'lr_,-Ixe, 1). _-|6

476 D_..[OII'WAL PAGE ]'S'

OF POOR QUALITY
_,". _=. : -_-: "E.__::_:._ _ -0:" ; ..--=.---. --: ._ ; _

.................... " ........... Ili-III III III I JL

I I i I l I _ l l _ I _' I I I | I

J l I I l I I ,J I, I. I, I I I

-- Caeo: LI.JUN-i7

Tfoe; 22:$3:30

(lay: O.Z

- J'NF: NO

-- HI C_PO04JPI _ i|_lt

C *l, Zz) ( -7, _s] 2_

" ( *z,*_'z] C Z,-1,z] zl

C-l, zs] (t,_'z) 2s

[ o. all: l, S]z_

_ (-$,-tZ) (-_,-zz) zz

( -z, zz] [ _, zl) Z3

[ z, z] ( 4, 4)Z4

- ( -S, 21] ( -3, 2Z] Z?

Trvth _ll_l[tJ_tt

(-1_, zz] £ -Z, ZI) zo

( -e,-Z4] ( z,-_?_ Zi

(-z, _) [ $, s] z4

. C-Z, sl ( z, zs) [t

! I

0_.__GINAE PAGE Ig

OF pOOR QUALITY

477
QUESTIONS AND ANSWERS

ROLAND BOWLES (NASA LaRC) - You mentioned wind shear alarms

several times. Could you tell me what alarm criteria you use,

and does it factor in the effect that it be dependent on whether

the radar is located on-airport or off-airport, and does it

consider the fact that the divergence information may be in error

by as much as a factor of six?

MARK MERRIT (MIT Lincoln Labs) - The simple answer is no to

both of the questions. The processes as implemented to date

obtains a measure of the divergence shear across the event based

on the process I described, and a threshold to that. Of course

prime continuity of that intensity applies a threshold criteria

to that. It is independent of the location of the event with

respect to the airport and is based primarily on measurement of

the radial shear. With respect to the errors in the measurement

of the shear, I presume you are reffering to assymmetry. The

assymmetry problem has not yet been looked at carefully. The

factor of 6 number is in fact not well supported. And this is

the subject of considerable investigation at Lincoln as well.

Observers have found looking at severe outflows that a line

rotated through the center in different directions can find a

factor of 6 difference in the velocity change across the event iil

different directions. That [)rocess does not correspond to the

approach I described here measuring velocity of differences.

(Which does not in fact look only through the center of the

event.) In fact, the report recently issued by Mike Eilts at

NSSL (National Severe Storms Laboratory) contains, there is now a

program which is not well reported in the paper where in fact he

took both approaches to the assessment of the assymmetry problem

where he looked at different directions through a center point

and one of the things he found was that the results of that kind

of analysis (that is the ratio to maximum to minimum velocity

difference seen through event) was extremely dependent on where

that center point was chosen. What he also did was he examined

various radar points offset the nominal distance from the event,

synthesized what the radar view would be from those different

directions and compared the velocity differences seen by the

various radar positions. What he found in all cases was a

substantial reduction to difference on the order of 2 to i, 2 .5

to 1 ma×imum error. So the detection process does not in fact at

this time take in account the a_symmetry although the system we

will be fielding next summer may well take into account the fact

that one form of assymmetry causes the velocity couplet to be

somewhat skewed at the surface and to rely not only on finding

differences along radials from the radar but also being able to

compare velocity differences with alignment somewhat skewed to

the radial direction that we hope will help counter the

assymmet ry problem.

FRED PROCTOR (MESO, Inc.) - How do you distinguish between

macrobursts and microbursts? A lot of what you have presented

478
seem to look more like what I call macrobursts than microbursts.

MARK MERRIT (MIT Lincoln Labs) - The primary requirement

here is that within a 4 kilometer region that we see a velocity

change at i0 meters per second. That is the criteria developed

by the TDWR LLWAS users group in the last couple of years.

FRED PROCTOR (MESO, Inc.) - Your definition of a microburst

is a little different from that being used by other people.

Usually a microburst is defined as having a horizontal distance

between diverging outflow peaks of less than 4 km, and a velocity

change between the peaks of at least i0 meters per second.

MARK MERRIT (MIT Lincoln Labs) - This is an issue again.

There has been a group, Terminal Doppler Weather Radar Users'

Group which has met a couple times under the organization of

people from NCAR. There goal has been to try and work out issues

like: At what point do you issue alarms; and what is the format

of the resulting information presented to users? And this issue,

of course, was discussed at length and this criteria which was

developed which by no means is a consensus among the research

community at all--the answer developed by that group which was

based primarily on input from I believe Boeing and researchers at

NCAR: Was this criteria of a specific velocity change within a 4

kilometer region? And you're right that is very different from

what a lot of other people are using.

JOHN CHISHOLM (Sierra Nevada Corp.) - You mentioned that you

are trying to use data at altitude. What is the status of that

work?

MARK MERRIT (MIT Lincoln Labs) - There is an algorithm that

has been reported (the copy of the first page of the paper in the

handout), worked on at Lincoln to detect these features and

notice, for example, that there is a core of reflectivity that is

sinking towards the surface and is associated with rotation.

That algorithm has been developed, tested extensively off-line

(again these ground truth cases), and has been scored using the

same scoring procedure and comes up with somewhat improved

detection performance at this point. And that algorithm will be

implemented in our demonstration system next summer.

JOHN CHISHOLM (Sierra Nevada Corp.) - Is it a useful

algorithm. I mean how beneficial is it?

MARK MERRIT (MIT Lincoln Labs) - Well, if you are asking how

much benefit you get by merging this information aloft in

addition to looking at the surface velocity, we have two bases

for experience. One is in Huntsville where we have predominantly

heavy reflectivity -- heavy rain cases. In that situation we

find that this 3-dimensional algorithm provides significantly

better performance, particularly in its ability to reduce false

479
alarms. In the Denver context, where we see a broader spectrum

of intensity reflectivity in the reflectivity levels, we find

that the added performance of this algorithm (given that the

tuning of the algorithm to the Huntsville environment), is not as

great. We are in the process now of refining the thresholds used

in this algorithm on the Denver data and we will have a better

idea of how much benefit it gives a little later.

JOHN CHISHOLM (Sierra Nevada Corp.) - In terms of your

outflow algorithm, at what altitude is the data most useful?

Right on the ground, 500 ft, i000 ft?

MARK MERRIT (MIT Lincoln Labs) - The examination we've done

on the surface outflow shows that the strongest winds are below

i000 ft. and we attempt to use information from an elevation

angle scan which both clears clutter and maintains the maximum

observation of those peak outflow winds. We are looking at the 4

to 600 ft. altitude region.

GARY BROWN (VPI) - Your algorithm for detecting at altitude:

If you detect at altitude, do you have another way to determine

what the magnitude of the down draft is resulting from that?

Because that is a different aspect to the problem.

MARK MERRIT (MIT Lincoln Labs) - Yes. There is a feeling

that one might be able to use, for example, the strength of the

convergence aloft to the decent rate of the reflectivity core, to

somehow get a handle on what the strength of the outflow is.

There is research work going on in that direction. In

particular, Marilyn Wolfson at Lincoln Lab is looking at that

problem. It is not developed to the point where it is an actual

operational capability yet. That capability has not been

demonstrated to be feasible but there is a belief that there may

be useful information there.

GARY BROWN (VPI) - Can I ask just one more? And that is,

you've done a lot of work with the detection using the outflow,

have you addressed the quantification problem yet?

MARK MERRIT (MIT Lincoln Labs) - Not in detail no. The

detection process is evaluated using the information that has to

date been primarily focusing on detectability, not so much on

accuracy in terms of quantifying the strength.

480
THE ADVANCED LOW-LEVEL WINDSHEAR ALERT SYSTEM

OPERATIONAL DEMONSTRATION RESULTS

SUMMER, 1987

DENVER STAPLETON INTERNATIONAL AIRPORT

BY

JAMES MOORE

ATMOSPHERIC TECHNOLOGY DMSION

NATIONAL CENTER FOR ATMOSPHERIC RESEARCH

FOR THE

FIRST COMBINED MANUFACTURERS" AND TECHNOLOGY

AIRBORNE WIND SHEAR REVIEW MEETING

NASA LANGLEY RESEARCH CENTER

OCTOBER 22-23, 1987

N88-17633

481
UKAI- I

\

Virga or

Rain

\

Steady \_

Wind \

Fie!d \

- \

Clou_

owndraft

\ Horizontal

Vortex /'_'_

1000 n

Approx

Scale

O_ 1000 tt

: Detection First

I

IMax Velocity Dit/erential j. 24 kn

Max

.... Intensity :_.::_

47 kn ......

• , . ; . . .

Distance 0.9 nmi • 1.5nm| ' 'i_..::.

Time to Max Intensity_ 6.4 rain

482
4

Number of

Measured

Microbursts

(500 I1 JAWS

Doppler 2

Radar Data)

Figure 17.

10 20 30

A

JFK

13! !

IIII

ILL1

Jill

llll

40 50

A A A

MSY OEN CRO

• Maximum windshear c:zpability of

jet transports at heavy weight.

for a shear encounter at a critical

Ioc:2tion, is 40 to 50 knots

windspeed change

60 70 80 90 100

A A A " Acc:aent

OEN OFW DEN Inc:=ent

Winctsoeed

Maximum C_anges Horizontal Windspeed Change (kt)

Mic:obu_t frequency versus intens;ty. _c:'dents hr.',.e _ccurred _n;,vinGshe._rs

within pe.dorm_nc_ c_.caCfiir/ oi a_r.ci_ne. Some wir, csr, e=rs c_.nnet be esc=..ced

r'O¢ ; ' [

suc,...s,utly.

483
E_.-N-HA_,_-CED LOW-LEVEL WITCDS_EAR ALERT SYSTEI_ (LLW-__S)

C ,._!GI>[AL [E_-STATION:

Spacing too c:ude to detect microbursts.

Original sLx-station algor:.th.m favored gust frontal wind shifts euud

generally did not detect mic-obursts.

Format of old LLWAS message was confusing; confusion assoc'ated

with ".his message lis_ed as contributing cause of Pan A.m Flight 759 in

New Orleans.

484
DRAFT

_mitaUon_ ,=.i-, @ LLWAS Stations e Sensor Jocnllons may -'tllow

microburst to go undetected _ _ _ Runways

Mlcroburs, may not be _ , _

detec:ed until reaching grounc J /' ,_ ,_ }

--/ Coverage only exists near J /1= - _ / .... "_.

,_Jnwavs. (inside middle marker),, / j,_ (._. =_ Mi_oburst'_

// __L_-l_ ._ \3 nmi

,J

!,,/

- , /ml I

k 2 ://

485
G

®

180! I 15l[ 25i

_so[ 5l

2_oj [ 271

3301 101

040] 61

1_40i 221

LLWAS WIND DISPLAY Q

486
ORIGINAL PAGE IS

OF POOR QUALITY

ENHANCED LOW'-LE'V'EL W-LNDSHEA_ ALERT SYSTEM (LL'WAS)

Z_"_"_£___ N C E D T VvZ L\'-E-'_"T_tT !© N:

de'-ecdnz microbm-._.

A_zor'hh_.-ISspec:.ficailyidentify. .,_,_.._l._ _ rr,--o,--.,_--c .,_... _-,,,-,r WZ.VD 51£EA_ A:aRT - -

m a 5rsz prio_;y, then identifies all other wind shear events dezec-ed

WfND _¢,.,._.._-v_..,_ALERT.

Format of enhanced svszem provides piiots with runway-or:,ented wind

sneaz m___=..

UNITED FLIGHT 226, RUNW._If 26 LEFT, M!CROBURST

ALERT. 50 "_Oz ..... T n:._ ON TPI.: PUNW'V

DELTA FLIGHT _'= ° '!, RuNT" t TS ,_Ax .... 17 PdGET, WiND S_EAR ALERT,

15 KNOT GAIN. 1 }fiLE =,_,"_T THRESHOLD W.,_'D 2S0 _' "_'_

CESSNA 9477 MIKE. RUbWAY 08 VTC._T WE_'D SHEAR ALERT. • -L_-_-_TJ_- -- _ .

15 K:NO " - 'T"= S_E...... _ R ! M,__n . -T '-" FINAL, THRESHOLD WIND 090 -._T i5;

WIND SHEAR OUTSIDE TZV NETWORK

_,i_,'e ....._r _ _S_i_ _. -_'_"----"":'_) 8---_.-_'-"_":"--" Si_i/_,_iOr'. " " ma.D-_',De .... disvlav in the tower.

-.oaooraise_.,.m.,,olh_- --- ,_'- interest it.such _.-disolav.

487
UKAI- J

-N

NW°

°

o NE

• CF

oSW

-SE

A2

1.= A3

A10 A0

_9

A6

A8

A 7

A4

A5

488
0

0

!

I

I

I

I

I

i

l

!

I

I

1

i

I

I

Y!

I

!

I"x/._

_. "/.Vz

t

er_

NlY/

b,'/f J,

i

I

I

I

° I

- i

I

i

I ,

u'J

tD

N

c_

T

ffl

_4

P

m

489

i I

___ c:. c:

i'- _ c:

c

N

P

P_..

<C

cl .II

EEE

ol

_D

C_ eir--1

..,.: ..,,2"

EE

I l___J 1__1

_ r-2--_

ff.j

o

_-- _J _-
n N|

OJ

la

w,--

-...

/:J

"% 490

r_O

0 _ CU
I_IBA 26 A

CF

330

190 15 G 25

15 G 25 P..WY 35-

MBA 8A 045 15 P.WY 20-

MBA 26 D 045 15 P..WY 35-

MBA 8D 330 15 G 25 ItWY 20-

491
CF 190 16 G 25

MBA 35 LD 160 22 G 30 B.WY 50-

MBA 35 RD 180 5 RWW 25-

MBA 35 LA 030 23 G 30 1 MF 55-

35 RA 180 10 3 MF 60-

MBA 17 LA 180 5 RWY 25-

MBA 17 RA 160 22 G 30 RWY 55-

17 LD 180 10 RWY 60-

MBA 17 RD 030 23 G 30 RWY 55-

492
CF 280 6

35 LD

35 RD

270

290

5

4

35 LA CALM

35 RA 280 6

17 LA 290 4

17RA 270 5

17 LD 280 6

17 RD CALM

493
No

Na

(. E_CH (=-SEE. PoLL

S

HO

NO

ye--3

• J

494
The Enhanced LLW:&S issues three kinds of alarms:

M-BA: ,.Microbur3t Alarm (Los_- _> 25)

W_A-: W'nd _,.aelr Alarm with LOSS.

WSA+: Wind 5hear Alarm with G_a ,,-N

,_wL

We have comDiled alarm stati-zticz for the month_ of AuG 1987 and have

distinguished between the active a.fte:-noon and evening period and the more

passive night and morning period. On average, we have found the following:

MBA

WSA+

WSATotal Alar.m_.

MQH'7-_/-Y

| ii i

ACTYv'E

Min/iO l=2rs Min/!4 Krs

/.G oT_ .g .&

q._ I.q 1.5 .1

i;_,3 5.9 I . 5 .2

COZvfBIN ...,_,

MW-_y

Au_

(,.S p.,o

14..3 g./

i

/ _,.a 7.'q,

c gA I/.2 1.3 1,1..s

44f34

AuG ao ta_4O ?,,_

A _- q l-rlle_ , S

<_OME AC'I-IUE- Z)AVS

to _ -F Co E,_- ToT4 t

a'ct I1,_ 1_'o5

3.e 5.5 ') ._

/o,¢/ 13._"

( ,,, _,,/ , o ,,_)

CF:,4

/3. l

:_,1

lg.E

495
WHAT WE -LEARNED FROM THE ADVANCED LLWAS OPERATIONAL D_MONSTRATION

MCCARTHY (OCTOBER 1987)

l o Alpha-numeric message quite successful frem controller

usage; several minor changes recommended that are being

implemented.

2 o Advanced LLWAS geographical situation display developed and

fielded for NCAR tower meteoro!cqist wer_ successful:

provided:

Advanced LLWAS wind field over runway map in a manner

that provided supervisory controller with means of

"seeing" two-dimensional wind field at airport, on an

approximately 5 n mi radius map overlay. In a nonalert status, this map provided limited ability for

supervisor to reconfigure runways, based on prevailing

wind situation (of course, wind shift prediction of

TDWR would substantially improve this capability, after

CLAWS results).

Map-type display of wind shear alert information, that

allowed supervisory controller to reconfigure

approachdepartures, depending on where alerts were

occurring (i.e., if alerts were occurring only on N-S

runways, controller would frequently use GSD to

determine that E-W runways remained viable.

496
o

°

--Page 2--

Pr_!iminary Advanced LLWAS algorithm results (general

impressions):

Microburst detection alerted on approximately 25 knot

differential (although alert threshold was divergencedependent). Worked apparently well, except that very

rare thermal that appeared divergent alerted system.

Microburst detecnion always reported loss, based on a

fit to a symmetric microburst mode!; likely

misrepresented wind field on some occasions, presumably

due to microburst asymmetries, or to semi-divergent

winds imbedded in gust frontal structures.

Wind shear alerts (station anomaly algorithm) worked

very well, except that thermals occasionally fired the

alarm; two types of WSAs occurred: wind speed loss,

wind speed gain.

No alarms were sounded if computed runway loss or gain

did not exceed ten knots; this was a demonstration

glitch - threshold should have been 15 knots. This

would have eliminated some inappropriate alarms (alarms

that presumably did not represent hazards).

Some sheltering clearly caused some false alarms; this

includes microburst and wind shear alarms.

Controller and Pilot feedback; still under review. Initial

reactions suggest controllers wildly enthusiastic. All

written pilot reaction favorable, but I have observed

caution regarding accuracy of advanced LLWAS.

497
lo

2 °

3 •

4 °

--Page 3--

MCC_R_."q_Y'S G_NERAL IMPRESSION OF ADVANCED LLWAS

OperaTional User Group display product concept very

successful; estimate of runway effects, tailored to each

_anway direction, made quantum advance in terminal

information content.

Ncn-aler_ szatus of advanced LLWAS provided exce!ien_

routine and very useful information to ATC; area supe_,iscr

will get advanced LLWAS alpha-numeric display in T_ACON; is

requesting GSD for supe_sisors in tower and TRACON.

Visual inspection of comparison between wind field seen cn

advanced LLWAS and alert message indicated at least

qualitative and some quantitative agreement; somewhat but

not always substantiated by pilots.

Advanced LL;_AS ccncept should be cornerstone of TDWR

operational display. In non-alert status, advanced LLWAS

winds need to be displayed on TDW_ 5 and 12? n mi GSD

display, and on TDWR alpha-numeric display.

498
TER_II!NAL DOPPLER V¢_ATEE.R RADAR (TDWR)

.... , - '_Z.-

• 2_unr.inz au_cma=ic mlc_-churz= ie--ac=icn algcri_hmz, off-:.ine, _o ;',erL+-

accuracy.

• Maintaining indeoendent a_sessmenz of microburs +. presence; verification

of all microbu_rst._ oresent.

• Over 200 microbursts identified within 30 km of Lincoln Lab radar since

18 May 1987!

• Goal is a Q.0.0u_ probability of microburst detection, and a I0n ta'se : ' _iar_. "

Scor;.ng is not yet ¢omple:e, bu_ results to da_e are very encouraging.

• A_suming 1987 scoring "_•- sat':sfactory, plan to have full TDWR 0oera_ior_al . *" '

demonstrat'_on in !988.

ORIGINAE PAGE IS

OF POOR QUALITY

499
1.

2.

3.

4o

SUMMARY OF TERMINAL DOPPLER WEATH]KR RADAR ACTMTIES

SUMMER, 1987

Mc__ (10-19-87)

Over 300 microbursts identified within 30 km of MIT/Lincoin

Lab radar'

Microburst surface divergence detection ground truthing

provided POD greater than 90% and FAR less than 5 % (target

was 90/10).

Microburst lines not well identified.

Gust front/wind shift detection/prediction not adequate.

50O
AiC-ORI ="_£M VER IFIC__.TXON

AND -_F_ PROC__-SS

CJ_<I',_;.LNALPAGE IS

.0_ P-OOR QUA/_T._

REA.L-'Im_

VF--R.IFIC_kTION

G'AOUND

TRUTH

I

l

S--rNGLE-DOPPL_-_ DATA: ASSESS THE FIDELITY OF THE _RITHi_

DU_-L-DOPPT_.--_ DATA: ASSESS _ FIDEL/._"_/ OF THE SYS_

501
1.

2 .

PLANS FOR SUMMER, 1988 OPERATIONAL DEMONSTRATION

Major RAP concentration on making microburst algorithm

output user friendly and displayable to ATC, using model of

Operational User Group as demonstrated with Advanced LLWAS;

Cleon Biter and Wayne Sand have action here.

MIT/LLwill concentrate on making 3-D microburst algorithm

run faster in real time.

3 .

4 .

5.

NSSL will concentrate on getting gust front/wind shift

algorithm to work effectively.

RAP will concentrate on developing sophisticated NOWCASTING

display system, utilizing Alliant/Symbolics/Pixar

combination with Lutz/Barron/J. Wilson talents.

Summer, 1989 advanced operational demonstration is

anticipated.

502
LOW-ALTITUDE WIND SHEAR RESEARCH AND DEVELOPMENT

THE MAJOR PLAYERS

THE LLWAS SYSTEM:

FEDERAL AVIATION ADMINISTRATION

NATIONAL CENTER FOR ATMOSPHERIC RESEARCH

FAA TECHNICAL CENTER

FAIRCHILD-WESTON, INC.

CLIMATRONICS, INC.

MARTIN-MARIETTA CORP.

THE TDWR PROGRAM:

FEDERAL AVIATION ADMINISTRATION

MIT LINCOLN LABORATORY

NATIONAL CENTER FOR ATMOSPHERIC RESEARCH

NATIONAL SEVERE STORMS LABORATORY

UNIVERSITY OF NORTH DAKOTA

MARTIN-MARIETTA CORP.

TRANSPORTATION SYSTEMS CENTER, DOT

503
QUESTIONS AND ANSWERS

RICK PAGE (FAA Tech Center) - Jim, just a point of

clarification. The graphic display that was in the tower during

the period of test in Denver -- I might want to point out to the

audience -- was not part of the LLWAS system itself. That

display Js not part of the LLWAS.

JIM MOORE (NCAR) - If I didn't make that clear, the LLWAS

display itself was a this and/or this [pointing to slide]. If

there was an alert status, this type of a display would be there

and if there was not an alert status there would be this type of

a display. The situation display was a separate color

graphic--it being used by people like myself and others to help

evaluate the system. The issue, the thing though is that the

supervisors especially were very interested in that display and

did come over and look at that quite often during these events to

see what was going on. Not only during the alert situations but

during more normal scenarios where they were interested in just

what the wind pattern was across the airport.

RICK PAGE (FAA Tech Center) - And another point of

clarification, although that graphic display will be looked at in

the future, it is not intended to be installed as part of the

LLWAS system in the immediate future. I want to make that point

clear.

JOHN CHISHOLM (Sierra Nevada Corp.) - Mark Merritt when he

was discussing his doppler radar said he had sort of a scorecard

or 95% probability 10% false alarms. If you did that for the old

LLWAS what wot_id the number be? And what would it be for the new

LLWAS? My gue£s maybe is a ... (paused)

RICK PAGE (FAA Tech Center) - As a result of the summer test

we are in the process right now of evaluating in a quick-look

report those exact figures. What we did is take an event and we

broke the event down into time slices and we evaluated, or are in

the process of evaluating, the relationship between the old LLWAS

and the new LLWAS. And we will have those figures within the next

week or two. The report is in draft status now and that will be

available to the community. So you might look for that.

JIM MOORE (NCAR) - In addition, I indicated that we had a

doppler radar on the airport that was looking up the runway

components as well. At NCAR we are trying to do some analysis

with the new LLWAS and comparing that to doppler radar data to

see how well we did.

JOHN CHISHOLM (Sierra Nevada Corp.) - One last question.

Has anybody said in order to make LLWAS as good as a doppler

radar I would have to put out so many anemometers and they would

cost so much versus the cost of a TDWR. Is it I00 or i000 or

would it be 2,000,000 dollars versus 5,000,000. Does anybody have

504
a crude number to that? I'm just sort of curious.

JIM MOORE (NCAR) - I don't know that a specific number has

been addressed, I do know that there have been studies done with

respect to what the spacing needs to be in order to cover a

phenomenon like microburst. The number 12 seems to be some

reasonable compromise. With respect to the resolution you would

get with a doppler radar (which might be 150-200 meters versus

what you are able to do here which is on the order of a

kilometer), you have a ways to go. I'm not familiar with the

exact number that would be required to make the match a true

one.

TODD CERNI (OPHIR Corp.) - Just a comment on his question,

you have to keep in mind that the surface base sensors don't

measure quite the same thing as the remote sensors. That is, the

LLWAS does not give you velocity along the glidescope. Okay? So

the LLWAS may sound an alarm after the events pass through the

glidescope and it's too late. This is part of the problem in the

Dallas crash. Another problem with the Dallas crash is that the

event was outside the airport property and the LLWAS sounded the

alert after the event took place.

EMEDIO BRACALENTE (NASA LaRC) - Are these measurements made

at i0 meters altitude? How high are they above the ground.

JIM MOORE (NCAR) - That's the standard height but there is

some variation. In the Denver area, especially to the west of

the airport there is the problem with a tree canopy very close to

the end of the runway. So they actually had to run the tower up

through the trees.

EMEDIO BRACALENTE'(NASA LaRC) - Has there been any thought

given to doing profiling to try to get winds at higher altitude

by acoustic techniques or whatever that looks up, would that be

useful information if that could be gathered?

JIM MOORE (NCAR) - Well there is a profiler in Denver for

which data is provided to go back to several of the groups in

Boulder. At that point it still is a point observation and if you

have a microburst that is not right on the beam, you are never

going to ... (paused)

EMEDIO BRACALENTE (NASA LaRC) - Well I was thinking at every

LLWAS location to have a profile in addition to it.

JIM MOORE (NCAR) - That could get pretty pricey.

HERB SCHLICKENMAIER (FAA) - Well, if I can add--and Rick you

can probably update this even more--there was some work looking

into using acoustics, lasers, not as a profiler but as a

replacement for i000 ft. tall towers. As Jim was saying, with

505
the practical day-to-day things that the LLWAS program has been

dealing with for years, one of those practical problems is very

very tall towers to get out of obstruction-type shear. Some

consideration has been given to it at this point--some very

preliminary tests have been going on. It is, in essence, to

reproduce what an anemometer does, and also be able to program

the height without all the mechanical constraints of a tower.

noticed there was about one more question to go.

BUD LAYNOR (NTSB) - Just in addressing the gentlemen's

question on the TDWR comparison with the LLWAS, I thought maybe

Mark might want to address some aspect of that. But it was our

impression that the TDWR can also be used to look at the upper

level convergence or the twisting of the core which would provide

some lead-time predictive capability that the LLWAS is never

going to provide. Even if you did go out beyond the field with

the anemometers on the surface.

JIM MOORE (NCAR)- Well I think John's [Chisholm] question

was only with reference to making a surface-similar type, the

lowest level scan and what the comparison might be.

BUD LAYNOR (NTSB) - Well I agree, but I think that if the

algorithm can be developed to give lead time it certainly is very

important.

JIM MOORE (NCAR) - Yes, the predictive capabilities of the

radar clearly outweigh whatever LLWAS ... (paused)

BUD LAYNOR (NTSB) - And the other question I'll ask Rick

Page is: I don't understand why the FAA would be reluctant to put

the CRT display in the towers as part of the LLWAS, or certainly

as part of the TDWR when it comes along. If it is indeed as

effective for the supervisor as it seemed to me as it was when I

was out in the Denver tower.

RICK PAGE (FAA Tech Center) - I did not say we were

reluctant to put it in. I just said that there were no immediate

plans to put it in the tower. We will be looking at that

particular display and other types of graphic representation of

the data. It is just that that particular display (although it

was in the Denver tower--and it was being looked at by the

supervisors) for reconfiguration of runways was not part of the

test, and the data that we acquired and the decisions we were

making in relationship to the display itself did not include this

particular display. That is why I made the distinction. The

reports that we will be issuing will be based upon the CRT

display.

506
N88-17634

INFORMATION TRANSFER IN THE NATIONAL AIRSPACE SYSTEM

Human Factors Research At NASA-ARC

Alfred T. Lee, Ph.D.

Aerospace Human Factors Research Division

NASA Ames Research Center

Moffett Field, CA

507
Alfred T. Lee

NASA Ames P.esearch Center

Infoli_,ation Transf::r in the NAS: An Overview of Human

Pactots r'.esearch at NASA-ARC

Although I had not planned on giving a formal talk on the

issue, I will atteml;t to give an informal overview on the

in-progress and planned _ork in the information transfer area

specifically addressing the human factors issues in the current

and future _AS. Information transfer is a general term which

encompasses issues as to what kind of information is needed, when

it is nec_ed and in what form it should be presented to aircrews

operating in today's and tomorrow's NAS. There are essentially

two fundament6, l reasons for this effo_t. First, there is the

mounting _vidence that tl_e existing system of transferring

informatio_ concerning wuather, traffic, etc. to the aircrew in

an accurate and timely fashion is simply not adequate. The other

reason ia tha_ f,lans for making changes to the existing system

ought to be driven by the needs of aircrews (and controllers) and

not simply by technology. This user-centered view of the

implementation of elei_ents of NASP will have to be supported by

substanti'J_ d_Lc_ on how peo_)l, will of,erate in this system if

those of us in the human factors arena are to make a viable

contribution to its design. The relevance, to the issue of

wine, shear and other severe _eather avoidance, of information

transfer" _hould be self-evident. Our focus from the human

factors standpoint, in general, is long range, measured more in

'/ears ti_a_i in f_,onths, so this work has a less direct relevance to

L_e_,e ?1oce_czngs with respect to near-term regulatory

i_,plic_tions. _ut llerb 6tsked me to talk about this to give you

an idea of what we are doing _,i A_es pertinent to windshear

avoidance.

The first element of the program _lan is look at the issue

of information transfer in the current NAS operating environment,

including problems associa, ted with the transfer of weather

informaLion. Our chief source of information on these problems

is the Aviatien Safety Reporhing Systems (ASRS) data base. A

_-ecent study of these i_rob]ems for incidents reported during the

calendar year_ 1985 and !9P,6 is due out this fall. A second

stu_Ty focusing strictly o_] weather related incidents is currently

in £_rogress.

'r',,_ second are in tl,e pro,gram deals with information

ttu_'_fe_ _ it might occur in the next generation }aAS, elements

of _hich c,re described in the NAS plan (brown book). In this

area the goal is to provide human factors guidelines for the

design of the information transfer system in the NASP and to do

so with as much specificity as possible. Task elements within

this area i,;c]ude addressing the problem of managing information

5O8
ORIGINAL PAGE IS

OE POOR QUALITY,

so the process of delivering the needed information to the flight

deck at the appropriate time can be achieved. While previously

the pilot served as the msanager of information on the flight

deck, it is becoming increasingly apparent that the amount of

informal ion co_icerning traffic, weather, etc. can overload the

crew. The evolution of new technology allows a substantial

increase in the amount of information available but, no increase

in the ability of aircrews to select, prioritize, and integrate

that information. Our task is to provide some guidance in the

design of such systems with respect to meeting the needs and

limitations of the humans who will operate within it.

A third task, related to future information transfer system

design, address the means by which that information will be

displayed on the flight deck. Included in this task are design

issues with regard to the type of information displayed, its

formating, whether the information should be displayed visually

or aurally, and other issues. Associated with the presentation

of information is the access to that information, i.e., data

entry and retrieval. Those familiar with the Flight 007 know

that this is a potentially nontrivial issue particularly in

highly automated operating environments.

The fourth task element is to develop appropriate

decision-aiding technology. In future NAS we can expect the crew

to have access to far more information in real-time than is

currently available. Providing a means, by which, to aid aircrew

decision-making, particularly in high workload terminal area

opera_tions, will utilmately enhance safety and efficiency. With

specific regard to severe weather avoidance, the provision of

displayed vectoring or waypoint information which may optimize

not only safety but fuel efficiency, is within current

technological capabilities. The integration of such

decision-aiJing components into the flight deck and defining the

optimal human interface remain a challenge.

Although communications engineering is not the focus of the

effort a brief discussion of this area seems in order. Much of

t_.is work rests on the assumption that conventional voice/VHF

transmission will not be the principal means of information

transfer. Ratl:er digital datalink transmission will likely be

the chief means by which information reaches the cockpit and is

sent to ground or airborne/orbiting stations. This would

presumably entail both Mode S, satellite, and conventional VHF or

FM station subcarriers, some of which are already in use.

Basically, the problem with some of these systmes is that they

are slow with regard to communications baud rate. I have numbers

on the Mode S system of 200-300 bits/sec. So one of the possible

research areas is to look at the tradeoffs in terms of

communications rate, particu1_rly with the regard to the

transmission of weather data at least as far as its impact on

crew decision-making.

509
In general, our ap[Jroach is looking at the area of

information _r:_l_fer is first, to use our existing data base

(e.,_., A gRS) in identifying current information transfer problems

and reco;,_,_ending solutJorzs. Secondly, to address human factors

issues i_ proL_osed information transfer systems for the next NAS.

rhe fac_litJe:_ at Ames Research Center will be employed in

_,rovidir_,j the data neces_;ary to define guidelines for these

systems. Both Dart syste=,s and full mission simulators located

at the Man Vehicle Systef.:_, Research Facility are being exploited

in this effort.

510
A I,.. 11 l.l P,7

INFORMATION TRANSFER

o OB.IEt'TIVE<

I II)I;NTII_ Ill M..XN I.A("I'OII_ I_,_t'E._ IN EXISTING INFORMATION

I"RANSIEll SYSTEM AND REt'()MMENI) SOLVTIONS

2. IPR()_ !i)1; HtMAN FACTORS (;IIDELINES FOR THE DESIGN OF FUTURE

INFOR MATION TRANSFER TECHNOLOGY

- INFOIIMATIOX MANAGEMENT

- INFOI'M._TI()N DISPLAY

- DATA ENTiIY ANI) RETRIEVAl,

DE('iSION-AII)INt;

511
INFORMATION TRANSFER (CONT'D)

o APPROA(:H

]N('IIH-;NT, A('('II)ENT DAIABA.qE ANALYSES OF INFORMATION

Ti-I ._,XsFER PIq()BI.EM_

REVIEV¢ OF ANALOGOUS INFORMATION TRANSFER SYSTEMS

PART .'.;_STEM.g SIMII, ATIOX STUI)IES 0"-g.. C[)V_I}

FVI,I, MISSION SIMULATION STUDIES

512
hLu

513
DISPLAY-BASED COMMUNICATIONS PROTOTYPE

o GROUND-AIR-GROUND DATALINK SIMULATION (¢a.1995)

o ADVANCED AIR TRANSPORT AIRCRAFT

o DIRECT COMPARISON OF CONVENTIONAL VOICE

AND DISPLAY-BASED SYSTEM

o MENU-DRIVEN, TOUCH PANEL CHARACTER DISPLAY

514
|

@I fl l_

_L

tVtlfLrg_

515
Or)

Z

0

w

ne

_3

"0

0

0

s_

13.

m

"0

0

s.._

0

-"ilmmm ,,C

13. _0

N88- 17635 :

_w

m_m

• 0

O'7,--

_-_i?,_ _,_ ,. , _i_ _ _

517
oJ

O)

_-uJ

rrz_-

¢/)

ILl

0

LI=

ILl

Ira

rr0

rr

,¢

I-- fJ)

LU

"r"

I--

rJ) m

(1)

,¢0

0

Q.. 0

..Q

L_

I--

¢1: ¢_" 0 ,...

mm

"0 O'J

r" f"| m 0 0

518
cO

GO

_- LJJ_

m<_•

0

n'z,-

n-

<1:

UJ mm

(/)

U.!

n- a

ILl 00

n.- nmn

m

cU0

Q. 0

13.

C)

t_

,<|0| m

O3

(-

03

r"

Bm

c"

!._

t_| mm

t_

c/)

II

O3

t_

le--

C)

ii ilmll

13.

It)

C3

--J

|

0

IQ. 0

s_

Q. 0

J2

:3

519
I--

CO

nm

Z

0

r'_

ull

_.J

rl

<

X

U.I

Z

co

r-_

Z

._J

<

0

13_

......... • ......... O"'O --O ........ , ........ • .........

:/ I I

0 • •

I I I

0 # •

d_o •

o_i,Q Q, o0 o0

I : I I "t-- CO

......... ;,..... O--;--O .... • ........ i--- II " II ....

/ I I "1- -I- 0 • •

I I I

o .o • N

I :I I _.

,,o_ ?: t',,Z \:: • o....,......;......... ......:........

_ ",< :"'_'._'--o\

: :0_ • • 0 ' •

" " _ : ; I ' I;

: : _' '0::_ : 0 : •

: : \ ._P_X : I : I:

: : _ _-O0 : O : •

• . \ /-",_: , : ,: :......... :.... ,.-s:........ .-o ..... ,........ •.........

: : _/:: ._ ' I"

: : : : "l-o. i

: : X: : _",_ n,

: : >: : OO .0_ •

: : : : I \: _1:

• : : : O i (O

! : : :_ _../" .'x.o

:......... "........ "......... !8--_O_'-:-O- ......... O--.

i _/ _, io/

(.3: • • o. ' I I: / :

uai • e: o:

I

0

(.0

CO 'F_.

I-- F-- LL

LLLL

0

O0 0

kO LD I.D

r_ II

-,- o II

,NI--

rr>i

I

0

LO

O4

0

0

0

LL

o m"

0

7

<

121

C_I

!

0 C.,'

! !

I I: / :

• O: O

I I : I :

.............. • ..... • .... O .... ; .........

•: •'

•' o' i

I I I

• • :O :

I I :1

: • • O

I I

: • • o

I x n

0 0 0

I

-0

inn

Z CO

C/)

m_ _

rr'z_

520
DOWNBURST ENCOUNTER AT TAKEOFF; LARGE JET

TRANSPORT AND LIGHT TURBOPROP TWIN

PITCH

ANGLE

OF

ATTACK

20

, -o-e-q_-I_

16

12

8

20

16

12

8

i.

U.l-li.n.i

4

0

m m.mm'm'm

o-.o zo-o-0

LAG E JET _o___ J,_'/

I-m-m-m-m-m-lI -tm-m-m-m )-.-I.--m-m-I m_--_-m-m-m -I--I

_ LIGHT TURBOPROP

140

AIRSPEED

120

SW

1O0 'mnm'mom'm'm'm'm

80

400

• • • • m-m I-m • •

SW

3OO

ALTITUDE

_....._o -

"$'0-- -- I/ I_1

L_.I ..,.l ,,,, l -I _"

_i°m" m'i'm-mm=i=m.'n_m_m_m_mm_.m_l,,,-m_' l

o...-C_C

_O_m,_Im morn !

200

100

olo,"

:).-'-_ O--

._o_e'_'o"_ _-..o.--e_o....e :_"0"-0...0. - O_..O._.O,... O

__mmrm/.:.m.'e: m.m-m-m-m-m-m-m-m-m-m-m-m_m_;t'_e.m- -m'm o/

m r I --e--.--" ..,,..o,""

0.00 1.00 2.00 3.00 4.00 5.00 6.00

DISTANCE, FT/1000

521

7.o0

R.S.BRAY

NASA-AMES

1 0/23/87

5
DOWNBURST ENCOUNTER ON APPROACH; LARGE

JET TRANSPORT AND LIGHT TURBOPROP TWIN

2O

PITCH

16

12

8

4

0

20

I I

,o.,o-,o-,o,_,,.o._4-o-o-___o=o- _ O-,O-,O--

nUL._O..,I ,a'O-- I /

d_ LARGE JET

A,,=m.=,,.i.i.v.in-,,-,,.=-m.,,.-=---I-m-i-_l-_m

 -o-o-7 "--,.,,

• LIGHT TURBOPROP /

i-I'l-I

ANGLE

OF

ATTACK

AIRSPEED

16

12

8

4

0

SW o....o- o-o_

,,._," .jc-o-._ '_o

o_O_o_o .,o_o_o . .,0" 0,,,,. o_

?_ "_-(>__o_o-o-O'-U ---- SW c ..o...o... O_o.,.,.o_°

i-.-,_._ i.u.n.u.m.U .i -i'n i "..m

I

P,-,-" I I

180

160

<- o,...o,,.

1 4 0 °_°' o...o_.< ...0--o---o-"

°'.o=_i_o :,9_O_o..o.. _- __>-_'_'-__o_.-o-'-'_,.-

120 ",,....,.. "_o.,,, __,._0"-- ..._-"

i ""O "_"O r 0=:: r,,.,_--_ O _,,._

.I.l_ "O _ O_O__O.,_ O _

1 I"'"I',,,- i

I'u'i,in • i i..,,- n'l

' "_i.i.l.i.i_l l._i.i_.l="

8O

500 .._

400•'Ii._. " n ' ,i,o.,., .... o-.o-o-o-o-c-o -°'_:_c _ °_°

n ,an-= • 9, mJ,m_,m.,;._m; m:_i. _'_",'_-_ ' - o,[-o...

300 " " -'"u ....I-I_ I . -"-O_. =..J _,.._ -$_''O'_I

ALTITU D E "I'I-I-m -'l:'ic'_--l--l"'_""--

200

100

0

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00

DISTANCE, FT/1000

522

R.S.BRAY

FIASA-AMES

1 0/23187

6
A COMPARISON OF PITCH ALGORITHMS IN AN

APPROACH ENCOUNTER WITH DOWNBURST SHEAR

PITCH

2O

16

12

4

0

oj.O_ O. ,O--O--O--O-O -O--O--O% O..,,O......,O_O_O_O..........O_O _O,.""

. % _o.=,O__o, .-

_:¢_ °/D/:_..o "°'-c_ -__ °"c_-°"_, c_"'c)"'_ "_--_-c_._

-o-o-d" _ P(_CH=5000/(H+150)

I

160

140

AIRSPEED 130

120

110

100

ALTITUDE

500

400¢

300

200

100

0

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00

DISTANCE, FT/1000 R. S. BRAY 6A

NASA AMES

loi2_/87

523
or) 0m

I->

nILl

U3 m0

.,..., .,.;

¢" (b

I._

--" ¢33 0 ,- m

00

(b..C m =#w 0 r.-

t._._

¢)" ::30

¢_.. c) 0 _ 0 (n

.0 ,.-

.,-,_

..c:0

m_

I_..o

e- _..

I-"0

524

I'--

(%.)

tQ)

mm0

t-O

smm

mm

r' -.-

Or)

>-L.U

<_<_ cc co • o

ccZ,-
N88-17636

Airworthiness Considerations

Ray Stoer _

FAA i _ . 6

525
6. AIRWORTHINESS CONSIDERATIONS.

a. Certification Program. This advisory circular provides guidance for the

airworthiness approval of both "annunciation only and "annunciation with

guidance" airborne windshear warning systems as many of the system design

aspects, functions, and characteristics are common. In either case, the scope

of the applicant's program should be directed toward airworthiness approval

through the Type Certificate (TC) or Supplemental Type Certificate (STC) process.

In the case of systems with flight guidance which will ultimately be used on

aircraft in air carrier service, the applicant is encouraged to undertake a

certification program which will satisfy both the criteria contained herein, as

well as that contained in AC 120-41, Criteria for Operational Approval of

Airborne Windshear Alerting and Flight Guidance Systems. Many of the criteria

outlined below in paragraph 6(d)(2) can also be satisfied in finding compliance

with § 25.1301 of the FAR, if the certification program satisfies both

operational and airworthiness criteria. A statement will be placed in the

approved Airplane Flight Manual indicating compliance with AC 12U-41, thereby

providing for a more streamlined operational approval process for an air carrier

under Parts 121 or 135 of the FAR.

b. Certification Plan. A comprehensive certification plan should be

developed by the applicant. It should include how the applicant plans to comply

with the applicable regulations and should provide a listing of the

substantiating data and necessary tests. Also, a comprehensive system

description and an estimated time schedule should be included. A well developed

plan will be of significant value both to the applicant and the FAA.

c. System Criticality. Certain types of failure cases must be addressed in

consideration of the potential hazard they may induce during the course of

normal system operation. Advisory Circular 25.1309-1, System Design Analysis,

provides criteria to correlate the depth of analysis required with the type of

function the system performs (nonessential, essential, or critical). Also,

failure conditions which result From improper accomplishment or loss of function

are addressed. The criticality of certain system failure cases for windshear

warning and systems with escape guidance are outlined in paragraphs (I) and (2)

below. In the case of systems which provide escape guidance, there may be a

number of complex system integrations with existing airplane systems and

sensors; and the treatment of all the combinations possible is beyond the scope

of this AC. In this case, AC 25.1309-1 states that the flight test pilot

should: (I) determine the detectability of a failure condition, (2) determine

the required subsequent pilot actions, and (3) make a judgment if satisfactory

intervention can be expected of a properly trained crew. In addition, failure

of the windshear warning system should not degrade the integrity of other

essential or critical systems installed in the airplane. This includes common

shared sensors.

(I) Windshear Warning. The system should be designed so that false

warnings have a probability of occurrence on the order of 10-_ or less. This

includes the failure of the system to annunciate a windshear warning as a result

of a ]atent failure.

(2) Systems with Escape Guidance. In addition to the criteria of

paragraph (I) above, the following system failure cases should be improbable in

526
accordance with AC 25.1309-I. (Consideration for out-of-production airplanes

with early versions of unmonitored flight director computers and mechanical

flight instruments is warranted, and those systems may have a probability of

failure on the order-of 10-3 or less.)

(i) Unannunciated failure of the system to provide the escape

guidance function when commanded. Removal of flight director command bars

constitutes adequate annunciation.

(ii) The display of escape guidance other tllan that evaluated and

approved in accordance with § 25.1301 of the FAR (see paragraph d, Intended

Function, below).

NOTE: The loss of windshear warning annunciation should not preclude or inhibit

the presentation of the escape guidance information, as long as the guidance

mode change annunciation remains valid and the annunciation is provided in a

clear and unambiguous manner.

(3) Software Based Systems. The software should be developed to a

minimum of level 2. An acceptable means for obtaining approval for the

development of the software based system is to follow the design methodology

contained in RTCA Document DO-I'/dA, Software Considerations in Airborne Systems

and Equipment Certification.

(4) Probability Analysis. The applicant should provide a quantitative

probability analysis to support an engineering evaluation of the system failure

cases listed above. For this purpose, an exposure time of 0.i hour has been

found acceptable by the FAA in the past. This criteria assumes that internal

system tests verify proper system status immediately prior to the system being

enabled. The probabiliy of the airplane encountering a severe windshear should

be I (one) and the c_aputed probabilities of occurrence should be expressed in

failures per flight hour.

d. Intended Function. The major emphasis for showing compliance with

§ 25.13UI is centered around the aspects of establishing a windshear warning

threshold that considers remaining airplane performance. For systems that

include escape guidance provisions, a subjective evaluation of airplane

performance is made to determine that the algorithms manage the available energy

in such a manner as to enhance flight path control beyond that which would be

normally expected without the use of the system. In addition, applicable system

integration aspects are'evaluated in order to determine that there are no

adverse functional effects with the existing airplane systems and sensors that

are integrated to the windshear warning system.

(I) Airborne Warnin_ System. The applicant must demonstrate by analysis

and simulation that the system warning threshold is appropriate for a given

airplane/engine combination. Once this aspect has been demonstrated and

approved by the FAA for a given windshear warning system, it need not be

repeated for other airplane models if the applicant can show that the technology

employed for this purpose is suitable. If applicable, system integration and

the use of external airplane sensors on the same or new model types must be

taken into account.

527
number of severe windshear encounters and conducted studies to determine the

criticality of flight variables like airspeed, altitude, thrust-to-weight ratio,

etc. This effort has resulted in the identification of a number of items that

should be considered when establishing alert threshold, flight procedures, and

training requirements.

(2) Warnin 9 Only System. The procedure added to the AFMS should contain

the following basic elements:

(i) Aggressively apply maximum rated thrust, disengaging

autothrottle if necessary.

(ii) Rotate smoothly at a normal rate to the go-around/takeoff pitch

attitude and allow the airspeed to decrease, if necessary.

(iii) If the airplane is descending, increase pitch attitude

smoothly and in small increments, bleeding airspeed as necessary to stop the

descent.

(iv) Use stall warning onset as the upper limit of pitch attitude.

(v) Engine overboost should be avoided unless the airplane

continues to descend and airplane safety is in doubt. When airplane safety has

been assured, adjust thrust to maintain engine parameters within approved

limits.

NOTE: Overboosting engines while at angles of attack near airplane stall

warning may cause engine stall, surge, or flameout.

(vi) Do not retract flaps or landing gear until safe climb-out is

assured.

(3) Warnin 9 with Escape Guidance System. In addition to providing the

information and procedures peculiar to the new system, a statement should be

made in the AFMS that in all cases of windshear warning, the escape guidance

should be followed until the maneuver has been safely completed.

528
QUESTIONS AND ANSWERS

BOB IRELAND (United Airlines) - Ray, I've got one quick

question for you. Could you bring up page 13 again that you had

on the board before? There seems to have been an effort made on

this page, and I applaud it, to recommend a manual recovery

technique which is similar to that which comes out in the FAA

training aid. The question I'm left with here is "(2) (ii)":

"Rotates smoothly at normal rate to the normal go around take off

pitch attitude." As you are well aware, the training aid does

specify other target pitch attitudes, they are just fixed target

pitch attitudes regardless of your gross weight or whatever else

might affect takeoff pitch attitude. And I'm wondering why you

chose to put something else there, when there is a warning on

this airplane, as opposed to when there is not a warning? The

FAA recommends just a fixed pitch attitude.

RAY STOER (FAA) - Because Bob, we are not trying to write

the flight manual or get down to the details of a particular

airplane type. What we are trying to do is say, "you should

consider these basic elements." As we went through this with

Herb and some of his people in our judgement, we felt that this

was not inconsistent with the training aid. If you are trying to

identify, perhaps, a specific airplane type then you might

say--well that doesn't fit as well. Our intention here was to

make some generic considerations which hopefully will bring to

the attention of somebody writing the flight manual, the kinds of

things that we would like to have considered. That was our

intent.

BOB IRELAND (United Airlines) - I understand the intent.

Would it, perhaps, be better to have said: "rotate to an

appropriately determined pitch attitude," rather than a specific

situation like that?

RAY STOER (FAA) - It may have been a better thing to do Bob.

BOB IRELAND (United Airlines) - Okay, I just wanted to

understand your intent. I appreciate that.

RAY STOER (FAA) - Even with the change we made here

[pointing to viewgraph] and I should point this out, that when we

got into the overboost concern here and we made this new number 5

here [pointing to viewgraph], we coordinated this immediately

with Herb, in fact we had a national telecom within the FAA on

this power plant subject. We had Herb on because we wanted to be

sure that whatever we did come up with was not going to be

inconsistent with the wind shear training document. Or at least,

if we were going to be inconsistent we wanted to understand that,

right up front. That doesn't mean that if we don't find

something is wrong we can't say it because we're inconsistent,

but we wanted to identify that immediately. In our judgement, we

are, from a generic standpoint, consistent with the wind shear

529
training aid.

BOB IRELAND (United Airlines) - That's great. Just a

comment on the engine section right there. I think that Ralph

and I could tell you that many, many days and hours were expended

in talking about engines in the training document as well. It

was a very very difficult subject and I really like what you put

there. I think it is a very good way to go.

RAY STOER (FAA) - Thank you. Our very first certification

with the wind shear system was about 7 or 8 years ago and I had

the pleasure of being on that with the United Airlines at the San

Francisco Engineering Base on a 747. It was a "one-only"

installation. It modified an existing Safe Flight SCAT (Speed

Control and Autothrottle) system in the pitch axis computer to

accommodate the wind shear escape guidance algorithms. United

took the leadership in this field at that time when we hardly

knew how to spell wind shear. And Safe Flight had so much

patience with us in sitting down and almost training us to what

they had. Again it relates back to the aspect that we have no

resources but people. We don't have any facilities to go out and

research things. We have to develop criteria concurrent with an

existing program and depend upon the manufacturer of that

equipment to teach and train us what he has. Our wind shear AC

(advisory circular) over the past 4 years--formally when we had a

team--and going back 7 and 8 years, has been a dynamic document.

It started as a one-page of what we think we ought to be doing

and has become a living document. And the reason that we are

going ahead and printing it now--at last--is because we have a

requirement within the government that if we have a rule-making

project in process we have to have a means of complying.

DAN LABRIOLA (Tech AirServices) - For those of us on the

training side - this Js _eally a good point about the engine

overboost and it seems it has really been a tough one because, we

started out saying that you should never overboost the engine and

you know max EPR's is what it was and we've been coming about on

that. But if we are going to start differentiating airplanes;

are you, or is someone, going to solicit and publish those

aircraft for which we can't recommend pushing the throttle to the

firewall.

RAY STOER (FAA) - Dan, I don't know the answer to that. Our

power plant group have an idea, but they don't specifically know

how many of the manufacturers and on what model types. The

individual manufacturers have independently looked at this region

cutside the envelope. And we never see that on the certification

program. Manufacturers don't like to show us anything they don't

need to. And that's okay, that is a defense mechanism on their

part and that's acceptable. They show us the operation of the

airplane Jn the envelope they seek to have approved. We have no

data, and many times we have no knowledge of how far the airplane

530
is taken out of the envelope and explored by the manufacturer.

We know that goes on and it's okay, but we don't have data or

knowledge of just what that is. I think what we hope is that

this kind of a "hey caution fellows, let's take a look at this,"

is going to stimulate the equipment manufacturers' interest in

contacting the manufacturer and perhaps on getting some data from

the manufacturer on this. This may also stimulate new model

types that are being certified into, perhaps, taking a look at

this region now that it is identified, that we will be operating

in this region more often because of the wind shear guidance

algorithms.

DAN LABRIOLA (Tech AirServices) - I would suggest to you

that if the FAA doesn't solicit this kind of information it might

be a little tough for any of the rest of us to find that out.

RAY STOER (FAA) - I can agree with that Dan, and that is a

good thought. We didn't want to hold this [advisory circular]

up, and we tried to work a way out that we could put something in

here that perhaps was defendable (and we think it is defendable

outside this document). But we really didn't have the time to do

that. And what I would like to take an action item to you, if I

may, is discussing this with the manager of our power plant

section to see, in more detail, if there could be some interest

generated within the FAA to look into this region outside the

envelope and how we can control that. If we say we have an

approved envelope, do we have the right to ask the manufacturer

to show us data? I don't know that, but I think we need to

explore that a little bit. It is a good point.

531
ORIGINAL PAGE IS

_0]_ IK)OR QUALITY

0/-_sl -T- 7--_

Myron Clark - FAA/HQ/Air Transport Div

Good morning. I didn't know Z was going to deserve a blue

ribbon getting down here. A funny thing happened to me on the

way to Dallas, I was going out the door Monday, or about to go

out the door, and my boss grabbed me and said "hey you remember

you're going to cover Langley for me" and I said "yeah, but I

don't get back from Dallas til Thursday", he said "that's all

right go on down there Friday and see what's going on" and before

I got out the door, he said "oh yeah, by the way you might check

and see what the status of the rule-making is, I think they want

to know." And so, here I am, I didn't even bring a view graph or

anything for you all to look at, but I did find the man that has

really been the driver on this rule-making and I can give you a

little bit of status on that. My facetious remarks aside, I did,

]ate Monday afternoon, take some time to find the docket and try

to do a hurried scan of the docket material. One thing I would

say, I guess we've been beating on this wind shear problem for

quite some time. (For those of you who don't recognize me as

being with f]i@ht standa_:ds, you might remember that I was in the

wind shear program office back about 1976.) But the comments that

came in on tills rule making were generally very favorable. I was

surprised to find that docket was not as thick as I thought it

would be. _]lere were good comments and a wide range of opinion.

It is always a good forum for people to speak their mind.

The rule was officia_lly published the first of June and the

dock_ is now closed. The comments revealed a wide ranging

public _wareness, on the phenomenon. In general, I think

everybody for the most port, zeroed in on the problem. There was

a limited amounh of wandering around discussing other issues in

the comments that were received. I would say, for the most part,

the people who wrote in or commented supported what we are trying

to do. Some did take strong umbrauge and disagreed strongly with

_he ide_ of retrofit (Ray Stoer sort of touched on that) and we

recognize hhe pt_oblem. Several of the companies substantiated

the problem--sttongly--tbat would be involved if we enforced a

total retrofit, so that issue is going to be closely looked at.

They also took strong issue, at times, with our economic analysis

of what the costs were going to be. There were some commenters

hhak urged thai.: we provide for the installation of look ahead

detection equipwent in the final rule. And one group said:

"let's don't pub helicopLc.rs Jn Lhis same box with us, will you

not." (And I think that came from the helicopter people,

truthfully.) They didn't want the helicopters to be included in

the ground training portion of the final rule that applies to the

escape procedures, since hheir airplane performance is not quite

like a fixed wing and the standard procedures may not apply.

I might point out, as you all know, there are already

several wind shear warning and flight guidance systems on the

PRECEDING PAGF- BLANI( NOT. Fii,J_,-_-D 533
market _nd installed a,qd flyii_g and this is not (as Ray has

fought tl,e battle for quJle a few years) something that is brand

new to _s all. _3e still see incidents occasionally, and we

haven't counte_] out wind :Jhear--it hasn't gone away. We still

need to ke<.t) ,,orkin9 on it, we're still faced with the fact that

we ,:_r, i_;i_g acci_ents t_at are attributed to wind shear. What

about t1_< rule maki,_g 0Jails? I think this is what you really

want to hear. For the final rule, and I'm going to read this

from a summary that was written by the man who has the prime

action o_, this. The "Rule Making Plan" is the title of the

summary. The FAA proposed revisions to the NPRM for the final

rule. I,_stallation of low altitude wind shear warning with

flight guiJa_ce equipment for certain turbojet airplanes operated

under pc_rt 12] should be expanded to include detection, and

/,rovide for a compliance date with a minimum of four years after

the effective date of the f_roL_osed rule. "Initially it was two

years. We got some very very strong strong input that two years

would jusk not be enough time to respond. They needed additional

time; so that it looks like the final rule is going to propose a

four ye_t comf,]_ance f,erJod"--and provide that flight guidance be

_equired on a_rp]anes built after a specified date that has not

been deteLmined y_t. In other words, we still have to decide

what tl,_it certain date is. If you manufacture an airplane after

a certain dote, you've got to build into it the flight guidance

requirement. And the other point under rule making was revise

the proposed requirement to provide that only Part 135

certificate holders op_ating airpla_es should be required to

develo L procedures for escaping from inadvertent low altitude

wii_d shear encounters. You know, I read this on the airplane

coming back fro,_ Dallas, and I'm not really sure what the writer

:_eant. "Revise the proFo_,ed reqt._rement to provide that only

P_t 135 certificate hold'era oL_erating airplanes..." ahh, that

is differe_tiating between helicopters. That suddenly dawns on

me that js what that's about. It was the complaint from the

helicopter f_eo_le. The botto:r line on this whole thing is we

have to re'_riLe the schedule on the rulemaking and that hasn't

been pub]ishcd yet - so stand by for the next issue. And I

rt,al]y don't k_ow what the rule makers will do as far as that

revised schedule. But, I am certain it will be another 60 days

before tl_e sc}_edu!e is even published on what the final rule

_,,aking will be. So it is going to be at least a couple months

before you see that in L_ri_t.

I also ,,oticed that Herb gave _,,c._- little opportunity to

talk about flight 'standards issues and views of new technology.

I will deli_)etately avoJC tl,e second _alf of that. How can I

9racefu]]y .-.-ay our view of new technology is that some times it

can |)e ovcr_,helmi_g and we don't want to commit to anything right

no_' in wriLing. Okay? Good government bureaucrat that I am, I am

not about to be pinned down on that issue too tightly. However,

I thought A1 Lee had bee_ reading my though when he got up to

talk. I don't know where he's been, I think he's been in some of

534 "" J_',_tt, PAGE IS

, 0._ POOR _.{:)Ua'IT'" " "_
ORIGINAL PA..3EIS

.OF.POORQUALITy

the same Jl,eet_Dgs with my boss, and some of the rest of the guys

from our shop on this new issues business. Data link, among

other things i.% an issue that from a flight standards point of

view is going to be pressing. We have a new boss that is quite

interested in that area, and so I think we are going to be very

izltercsted because if we aren't interested in it, he's going to

ensure that we get interested in it. I'm on a working group that

is addressing the issue of how to accelerate our current programs

when it comes to data link. And not just what A1 was showing you

with Mode S data link, but I think it is going to look at other

alternatives for data link that are available, that includes:

satellite, UHF, VHF, HF, the current ACARS System that many of

the carriers are using. How can we expand ACARS operation and

ilow can we support them? So, that is an issue with us, and there

is going to be _ore and more work put into that area in the very

near future.

Anotl,er thing that 18 always of concern--training issues.

_le've got to make some decisions--some hard decisions on

training. For you all in the manufacturing group, I don't know

that this is near as critical an issue as it is with the

operators of the major carriers. Does wind shear training entail

a requirement to add to the total training hours or are we going

to knock soraething out and let them maintain the number of hours

that are now required for training for recurrency and for initial

trai1_ing? Those decision_ haven't been made yet and I think it

is going to be a little while before you can really come to the

conclusion,s--draw the right decisions in that area. There is a

lot [:_vo]ve,] in wind shear training. I personally happen to be

very involved in weather programs for the branch and for flight

standards. I guess my official title really is weather programs

manager for flight standards. Beyond wind shear, there is a

concern that maybe our pilots are not really getting a good

tmderstan_Ting of weather. Maybe there is a field to be plowed

out theLe .... a fertile field to take a look at what we are doing

and what we are offering our pilots and what we are requiring of

them as far ,_c. just underlying basic knowledge in weather. So

that ties into the traini_g issues and these things are very

pri:,e issue8 for flight standards right now.

Cockpit resource management, that is, I don't want to call

it a buzz _ord, I don't want to tread on anybody's feelings about

that, but it has become kind of a key set of words that you see

crop up all over thc _ place. Cockpit resource management. What

the devil does that _f_ean? Well you get the airplane in the air

and you try to do i[ safely and try to get back on the ground

without burring it or anybody. And you use everybody in the

cockpit to do the jcb. Wllat else is new, right? Well, there is

a lot of work going on ir_ that area, and I think that you are

going to see more a_d more consideration given to how we handle

our procedures in the cockpit. We have kind of, ah, I better

not, I'm not sure wl;at the schedule is. I maybe ought to ask A1

535
to comment on that again. A] might have a better feel for some

of the thirlgs that are co_,ing down the road, but I can assure you

that there is going to be a hard look taken at the way we manage

our coc'<_JJts and there are plans for some seminars and for

additional meetings, training and workshops in that area, and I

think you are going to hear more and more about that in the very

near future froi,_ the fliubt standards. I think I already touched

on the Isst item, I really had a note here on the weather for air

crews. ;_}'eare concerned, not only just from wind shear

stand[_oirt--that too, certainly that--because that seems to be

the most dangerous of the weather situations we get into. But

the issue that we are gettir_g ready to address and we will look

at _ery c]os<_ly, is what are we providing to air crews? Are they

getting _hat they really i_eed and if not, what can we do to

pror_ote theft? And I _J]] entertain questions from the floor, if

I can't answer them I'll certainly take an IOU on them, and try

to get you a response.

Anyone? Weather is great in Dallas. Cowboy fans are crying.

Fort :Jorth Ti._,eS headlines says: White and Dorsett Take Charge,

Cowboys Lose. Got .]ny Texans here in the crowd that are going to

throw rocks at _,e?

Anybody? Okay, tlkank you very much.

536

ORIGINAL PAGE IS

OF POOR QUALIT_
D3JG1NAL PAGE I$

D_ POOR ©I_ALITy

STATUS REPORT

_IRBOkNE LOW-ALTITUDE WINDSHEAR EQUIPMENT

AND TRAINING R£QU£R_MENT_

BACKGROUND:

o FAA published Notice of Proposed Rule Making (NPRM) No. 79-IIA

on June I, 1987 (52 FR 20500), whlch solicited comments and

recommendations to solve the wzndshear problem.

o Comments received reveal public awareness of the phenomena and

a commitment to help solve the problem through new technology•

Commenters generally agreed that airborne equipment is needed;

however, they disagreed that filgnt guidance retrofit is needed

and they took issue with tne FAA's economic analysis. Other

commenters urged that the FAA provkde for the installation of

look-ahead detection equipment in the flnal rule and that

helicopters not be lncLuded in the ground training portlon of

the final rule as Ic applies co escape procedures slnce not

enough zs Known about how alrcraft other than alrplanes are

affected by low-altitude windshear.

o Several airborn_ windsnear warning and flight guidance systems

are certified and installed in certain turbojet airplanes•

o Incioents of encounters wlth hazardous low-altltude wlndshear

by air carrier airplanes continue to be reported.

o home accident investigations nave listed Low-altitude wzndsnear

as a posslbLe contributing _actor to a number of general

aviation accidents.

KULEM_KING fLANS:

o The FaA proposed revislons to NPRM for the Final rule -

• installation o_ low-aitltude windshear warning with flight

guidance equlpmeut lot certain turbojet airplanes operated

under Part 121 should be expanded to include detectlon,

provide for a compllance date of a minimum ot 4 years after

the effective date of the proposed rule, and provide that

_llgnt guidance be required on airplanes built after a

specztled date £o be determined later; and

• revise the proposed requirement to provide that only

Part 135 certificate holders operating airplanes should be

requlred to develop procedures for escaping from

Inadvertant low-altltude wlndshear encounters,

KULEMAKING SCHEDULE:

o The FAA is developing a milestone schedule for the final rule.

537
COMPUTER RESOURCE MANAGEMENT, INCORPORATED

Rosemarie L. McDowall

,-_._._,L_li_G F_,C_. E_K NOT FILMF-.D

CRMi J

539
\

I ,

If,

CRMI HAS BEEN ASKED BY THE FAA TO CREATE A DATABASE OF

INFORMATION ABOUT LIGHTNING.

A. HAVE BEEN WORKING ON THIS TASK FOR A YEAR NOW.

B. TASKS

1. PLAN THE PROJECT.

2. IDENTIFY SOURCES OF INFORMATION ABOUT LIGHTNING.

3. SET UP THE DATABASE.

4. CONVERT IDENTIFIED SOURCES.

5. STATISTICAL ANALYSIS OF THE DATA TO PRODUCE A

WAVEFORM CHARACTERISTIC OF LIGHTNING.

PROBLEMS WE HAVE ENCOUNTERED.

A. IDENTIFICATION OF SOURCES - NOT A MAJOR PROBLEM.

B. GETTING INFORMATION ABOUT THE DATA FROM SOURCE OWNERS.

1. DATA IS OLD.

A. POORLY DOCUMENTED & NO ONE REMEMBERS WHAT'S

THERE.

B. POORLY STORED; MAY NOT BE READABLE.

(i) ATMOSPHERIC CONDITIONS.

(2) DATA STORED VIA OBSOLETE EQUIPMENT.

C. ORIGINAL RESEARCHER IS NO LONGER AVAILABLE.

D. ORIGINAL RESEARCHER IS NO LONGER INTERESTED.

C. DATA IS NOT CONSISTENT FROM ONE SOURCE TO ANOTHER.

1. IN ROUGHLY 20 SOURCES, THE ONLY FIELD CONTAINED BY

ALL 20 WAS THE TIME.

2. DIFFERENT RESEARCHERS FOCUS ON DIFFERENT PARTS OF

THE LIGHTNING EVENT.

A. MEASURE DIFFERENT PARAMETERS.

B. TRIGGER MEASUREMENTS DIFFERENTLY.

CRMi

540

.)
D, - CREDIBILITY.

1. RESEARCHERS DON'T BELIEVE IT CAN BE DONE.

A. DON'T WANT TO BE BOTHERED.

2. BELIEVE THAT IF IT DOES GET DONE, THE RESULTS

WON'T BE BELIEVABLE.

Ill. SUMMARY,

CRMi J

541
QUESTIONS AND ANSWERS

EZEDIO BRACALENTE (IqASA Langley Research Center) - Do you

definitely h,,ve D]]ns to _ri, to t_ut a wind shear data base system

together like you did with lightning? Is that in the works?

ERNIE ADMIRAL (Douglas \irc[aft) - I was wondering if you

::ould give us just a little brief historical perspective as to

how long this activity has been going on and basically what type

of data fou are looking for.

ROSE MARIE MCOOWELL - W,-_'ve been working for about a year on

this. We are somewhat behind schedule because what we found was,

talking with the researchers, it is hard to get data from them

_bout w!,_t data th,_y have. !t ]s like catching smoke for a

bonfire in a bed sheet. It is a lot harder than we thought it

_¢ould be. we are behind schedule because we haven't identified a

machine to _{ t t],_: data on. That is in part because although

some of the airborne stuff have, they have very few strikes but

they have loads and loads of data. Wave form data takes up an

awful lot of space. If we go for periphia] information such as

tempe_rature , altitude, air speed, turbulence condition,

precipJtatio< intensity, precipitation type--on the C580 [Convair

580) three years of data have 41 strikes. So there are very

small numbers of records and very small pieces of information and

you can put that on a PC. But if you look at the wave form that

you want to sam_?le every 5 n_=,noseconds for an event that

lasts--not a second, a second would be too long, but you are

still talking a great number of sampling points on a wave form

and to do thak, we've come L_, with a rough estimate for existing

data of something on the order of 25 gigabites. Now we can't

quite do tl,at o;: a PC. The question is where do we _ant to go in

between? In th_ lijl_tning community the waveform is very

important. We want to be able to say to a manufacturer not just

this ]s the ,,eak current but this is the rate of rise, this is

the r_te of fall, this is ti_ continuing current because those

are all so important. Does that answer the question?

ERNIE ADMIRAL (Douglas Aircraft Co.) - Pretty much, yes.

Th_nk you.

JOE YO[]SSEFI (Honeywell) - C_n you tell us who we would

contact to get information on the lightning data base? What

source we should contact?

ROSE MARIE MCDOWELL - People who want to talk to me about

the work that I have done, c_n co_ta_:t me at Computer Resource

_lanagement. My phone number is 609-484-6911. The official FAA

contact for lightning would be Mike Glynn and his number is

609-484-4138. Thank you.

542

ORIGINAL PAGE IS

D]_ POOR QUALITY
SAM SAINT - COMMENTS

The very considerable attention being given to onboard

"predictive" systems for wind shear warning, grows out of the

fact that we would all like to give the pilot an earlier warning

as to when he should abandoned an approach or takeoff and go all

out to escape the microburst that has suddenly appeared in front

of him. We would like to give him earlier warning. I want to

point out that there is an option for earlier warning in the

"reactive" systems that has not been given enough consideration.

I refer to the option of asking the on board reactive system to

warn on energy gain as well as on energy loss. The reactive

systems are coming. I heard someone say yesterday, I think, that

4% of aircraft are already equipped. FAA I think, will be making

a rule to mandate the use of the currently available on board

wind shear warning systems. So, the question is should we ask

the on board computer to tell us when the outside environment is

seeing an energy _ that is outside the limits of normal

turbulence? This information is in the computer. As a pilot, I

want the computer to warn me that something is going on that is

outside the limits of normal turbulence--whether this is a

measure of energy gain or a measure of energy loss. And when I

get that word I want to be on the way out of there. So the

question is, should we warn on energy gain? And I'm not talking

about a caution alert. Some manufactuerers of windshear systems

are given a "caution" alert on energy gain. I'm confused about a

caution alert. I'm talking about a "warning" on energy gain. I

agree with Ray Stoer that we should not give a caution alert,

whether on energy gain or energy loss, that is triggered at a

lower threat level than the warning level. I'm talking about a

warning that calls for pilot action. To find out how valuable,

how important it is to warn on energy gain, I have gone back to

look at the accident record from Eastern 66 in 1975 to Delta 191

in 1985. So let me read just a simple statement of what I found

in each of these 8 accidents in the NTSB records. And I might

add, in looking at these accidents I assumed that we would warn

on energy gain, I assumed also that we would warn during the

takeoff roll.

In the case of Eastern-66, June 24th, 1975 at JFK, the

warning would have come 22 seconds before impact with the

airplane at 420 feet, ballooning above the glideslope, with a

head wind of 17 knots and an updraft of 300 feet per minute. Two

seconds later he was looking at the loss of that head wind plus a

1200 foot per minute down draft. What actually happened was

disasterously different. Those pilots didn't take action to get

out of there until 2 seconds before impact in the approach

lights. If they had pushed the throttles and gone to a go round

mode at 420 feet while balooning above the glideslope, instead of

pulling the power off as they did, there is not much question.

That accident would not have happened. The go-around would have

543
been a relaxed operation.

Continental 426 at Denver. This takeoff at Denver, got up to

50 feet and crash landed back on the airport. The warning in

this case, LKi__ne___ain, would have come during the take-off

roll, on the basis of the 7 knot per second increase in the

headwind outflow with a ground speed of 70 knots with i0,000 feet

of runway still in front of him left to stop.

Look at Allegheny 121 at Philadelphia. This pilot decided to

go around at 60 feet on approach. In 17 seconds this aircraft

went from 60 feet to 260 feet and back down to a 10-G crash

landing in the middle of the airport. That is what actually

happened. But what do you think would have happened if the

warning had gone off __enp_l__g_ while these pilots were 270

feet above the ground, looking at 160 knots in rapidly increasing

headwinds. The problem this pilot was struggling with was how to

get rid of that extra speed--extra speed that he had all the way

down almost to the point where he started his go round at 60

feet. If he _ad started out of there at 270 feet I just don't

think that pilot would have been on the deck a few seconds later

with a broken back.

Continental 63 at Tuscon is the fourth windshear accident in

the MTSB record. In this case a takeoff roll was started with a

40 knot headwind. We are looking here at a warning on the basis

of energy loss. That warning would ]_ave come 26 seconds into the

takeoff roll, at 90 knots with 4500 feet of runway left in which

to get stopped. The NTSB figured all he needed was 2200 feet to

get stopped.

Then came Pan American at New Orleans. This warning would

have come right at liftoff. And the thing that would have kept

him 130 feet above the tree line, that he eventually hit would

have been the warning at liftoff, telling him to put the power

all the way up, and keep it there, plus recovery guidance on the

pitch command basis to optimize the escape trajectory. And

again, what actually happened was disasterously different. The

actual knowledge of the problem they were in did not come for

these f_ilots until after they had peaked out at 150 feet and were

actually on the way down. The Captain said to the Co-pilot,

"you're sinking." They should of had the warning right at lift

off, put the power on, and followed the command bars in the

recovery guidance mode. Safe Flight figured they would have

passe_ safely, 130 feet above the tree line.

No_ w_ get to United 633, a takeoff at Denver. For those

pilots the warning would _ave come on energy gain 33 seconds

after brake release, with 8300 feet of runway in which to get

stopped. The warning would have come on energy loss a short

space after that, with still plenty of time to stop. That

_;arning, on energy loss, would have come at just about the time

544
the Captain testified later, that he was considering aborting the

takeoff. But he did not abort. When the airspeed started to

pick up again, he decided to keep on going. He ended up burning

a track in the grass for 1074 feet off the end of the runway with

the tail engine of the airplane and knocking out the antenna of

the ILS system. If he had been 5 or 6 ft. lower I think he'd of

scattered that airplane over a 1/2 mile of territory. That is

how close he was to total disaster. But the point is, he would

have had a warning on energy g_in early enough that he could have

coasted to a stop.

Let's look at number seven. This was USAIR 183 at Detroit,

a landing approach. This one is a confused mish mash of stuff.

Any one of several things, including better training would have

kept that pilot from second guessing the situation. He started a

go round and then he came out of the storm, the runway was in

front of him and he changed his mind and decided to land. The

gear wasn't down when he finally impacted. Almost certainly the

words "Windshear_ Windshear_ Windshear_" from the cockpit

loudspeaker (and recorded in the cockpit voice recorder) would

have kept that pilot from second guessing his original decision

to go around. The airspeed record indicates this aircraft was in

no real danger.

Finally, there was Delta 191 at DFW. The warning on energy

_I_, for Delta 191 would have come at 770 feet with 173 knots on

the air speed indicator. Which of you in this room is going to

tell me that if the warning from the cockpit loud speaker had

sai_, "Wind shear, Wind shear, Wind shearS"--at that altitude, in

that strong wind outflow, with a starting airspeed of 173

knots--which of you will argue that the go-around would have

constituted any problem at all? Those pilots, knowing that

warning was going into the voice recorder, would have been on

their way out of there. If they had pushed the throttles at that

point, with all that energy going for them and all that

altitude--if they had pulled the gear up and gone to go around

flaps, they would have been somewhere like 900 or i000 feet over

those water tanks instead of appearing on millions of t.v.

tubes.

The warning on ene_%y__ for Delta 191 would have come 27

seconds before initial impact. Still plenty of time for a safe

escape, but the warning on energy gain would have come 35 seconds

before initial impact.

What actually happened was sadly different. The record

shows those pilots didn't know the trouble they were in until 17

seconds before initial impact. At that point--where they pushed

the throttles all the way for the first time (those engines were

never up to full power until ii or 12 seconds before initial

impact)--at that late point in time those pilots were into a

dangerously different ball game.

545
[]Jti_ thi'_ I rest my case. A "reactive" windshear warning

system, especially one that is programmed to warn on energy gain,

as _;e]l as on energy loss, would have changed the accident record

dral:;atically for the better.

RAY STOER - FAA Aircraft Certification

Sam, I have one com_ent to make on that. We concur in

principle to your remark Sam, and let r_e read from the top of

page 8 in the advisor circular. The paragraph is entitled:

"Caution Threshold." Altl_ough not specifically required, the

applicant should provide the system with the capability of

detecting a rapidly increasing head wind or updraft and to

display this condition with a caution annunciation. These

conditions are routinely precursors of severe adverse wind shear

conditions. So that is an endorsement by the advisory circular

of your position. We do everything but require it. And we are

really in a weak position to make a requirement in the absence of

a regulation1 or rule, Sam.

SAM SAINT

I understand your position very well Ray, and I appreciate

it. Ray, the only question I have about that is that I think we

should be thinking in tet._._ of this being a warning which

requires acticn rather than talking about a caution. One of the

biggest problems I see in examining the records of various

accidents is the f_rob]el_ that we give the pilot a whole cross

section of information as to what other pilots said, what the

LLWAS ]_, :{ayil_g and a wlJo]e lot of other things, and then we toss

the Frob]em back to the pilot. We are suddenly asking the pilot

in three secor_ds, to sort this all out and come up with the right

answer. ]Je have got to do something better than that. I want

something simple that tells the pilot, with reasonable accuracy,

what is happening outside--when the outside environment has gone

outside the limits of normal turbulence.

With this simple warning we would then be telling the pilot:

it is the best judgement of a lot of qualified people, including

your own mangement, that the smartest and safest thing to do is

get out of there.

I think we all recognize that the pilot is still in charge

of the aircraft, but I think we should also agree that, if the

escape manueuver the computer is calling for is a safe maneuver,

the pilot should act on it, because the pilot has no way of

knowing what may still be ahead. It is my feeling that the pilot

should not countermand the computer's warning unless he knows

with certainty that there is a terrain feature that is known to

trigger an unnecessary alarm.

546
QUESTIONS AND ANSWERS SESSION

23 October 1987

D

BOB HALL (Airline Pilots Assoc.) - We are here today as an

industry to develop wind shear warning and guidance devices. In

order for a user to evaluate the device we think it is mandatory

to establish a baseline from which all guidance systems can be

compared. One such baseline could be the trajectory work done by

Dr. Angelo Miele of Rice University. There may be others, but in

any case a baseline should be established.

ROLAND BOWLES (NASA LaRC) - I think I ought to discuss why

NASA got involved in that. What the intentions were etc. Three

and a half years ago, several people came to us and said:

"Wouldn't it make a good study to investigate, for a given wind

shear, what the best we could do with a given airplane

capability, keeping it in the air as long as you can and cover as

much distance over the ground as you can." Since not a lot of

work at that time had been done of a very substantial level, we

thought that was a good idea to pursue. And NASA has funded that

for three years. We were dealing with Dr. Angelo Miele whose

reputation and credentials to do that work are extremely good: he

is a we]l-accepted individual in optimization theory. We even

go_ into some very elegant classes of optimization such as

"Mini-Max's." Least Squares, minimum error, quadratic error, went

by the wayside. Bill Melvin was introduced to this problem and

helped Angelo formulate the basic questions. We let Bill Melvin

stay involved in that work soley to advise on the practical

aspects of Angelo's work, because Bill is an experienced airline

ca[)tain and had a lot of background in wind shear.

The work is to be considered basic and fundamental. The

il. _stry should learn lessons from it. But nobody has been

successful in implementing those techniques in practical flight

director guidance concepts per se. That is, no flight director

concept that I know of yet--and Kioumars you may want to speak on

this--has been developed which will implement optimal guidance as

formulated by the work out of Rice University with Miele. What

you heard from Dave Hinton was a close approximation to that.

Dick Bray has done this kind of work over a time. Kioumars is

doing it present]y and we all will continue to do it. We are

learning lessons from Jr. It was discussed by the troining

team. Charlie Higgins who was leading the industry/training

consortium at the time, posed this to the team as a possible way

to compare recovery techniques: Do the best the airplane can do.

Through analysis, manufacturer's could compare their concept to

the best you can do. Overall I think that the team came to the

co_clusion that this is one way, but not the only way. And what

was already being done is just as good in the long run. So it

got put on the back burner. That is about all I can say about

it. It could be done, but it is not the only way to go about

working the problem.

DICK BRAY (NASA) - I would soy that in effect this has been

547
done and still is bein.] done. Roland, the otller da/, in a

discussioa on this matter sl_:_ted what I fit'l_il.].ybelieve

too--llistory tells us that bi, tile Lime yc)_.lhave _ecogt_i:.:ed you

_:,t-eir_ a shear you are a]readiz very slow. So that the difference

between most of the optima] trajectories in which you will get b]

some simpler methods, from that particular flight condition are

hal: as greatly different as might be seen in a purely analytical

study (in which everything happens right with the start of Lhe

shear from your nominal flight conditio!_). So, to my mind, the

memo the_e on the view gra[_l-1 implies that this hasn't been

considered. I would say that this has been considered. Would

you agree?

ROLA_D BOWLES (NASA LaP.C) - i_l di!.;c'ussio_l, Sperry indicated

they have used some of ',:[li::;l_.:_]c, wo_k to ar_J,/e at a practical

i,l_pleme_tation of the F factor r<,covel/y guidance technique. Ma_y

people have looked at it. I thii_k the AerosL0atiale people have

followed the woJ/k to some extent v11d l_iave c _pita]ized on it. I

think the point is: the (]:iff.,r<,nc< iiJ doin] batch analytical

simtl]ations with cerLain state infer-real_ion and perfect knowled:3e

of a threat windfield environment Js one thiBlg and it is

valuable. But, ar; Da\z<. lij,ll:)ll:;flowed, when i,ou close the loop

with the pilot, things 'oo.]i;_ to wash otlt and advanta<]es of one

technit]ue, some of the "op',:ii,a] ,7_L)/Jro;-J,i_ol:iol_s"soft of wash out

relative to what is cor_ei_t]y beialg recommended in i-he traininj

prscedure. So, it comes down to vet-y small differences cai_ make

bi] changes. And ,jiven ihe u_certainty of human performance

closure around the machine _J_(] other things iL would be useful

but: I don't think it is a compel] ::o_,]thing to do, frankly.

BOB HALL (Air]ii_r._ Pilot.: Ass()c.) -- I wasn't nece:;sari]y

trying,] Io L)usI_ anybody's the,.)c], over d,1other but Jt just se<_med

[:l_,_t if y(_tJ are _ J_,n._t_.c,-_,:',_,.r trx/in,j I o h_j]d sor, w. thing ]z:->u

o<_,jht Io have some. baso]ir_.. I,_ ;_<. g(_il_ 3 by. And .if you ac©

U_it:ed Airline's, a,- who_,vc:c, tryi,_,,'3 t_, 1ol2], :;c_methirlg then you

would ]ike to have something to judge :it by. That: was; the onl I,

thought, and I think we have _enerated enough discussion. I'm

satisfied with what you are saying.

PAUL CA._IUS (Airbus Ir_d.) - I_q L)rii_,=ip_i it might be very

intocesting to compare diff.-:i,,tst so]utJ,_ns, but from present and

past experience we have s,;<,_; that thee<: a_'e very large vaciations

even betwee_ identical runs witl_ ',:h, s<,me situation, s and coming

out f_.'om differen',: pi]oLs. 73u[, what I would suggest is at least

to show that with an auto,.g:_tJc systc..m we: can do better than with

a i,anua] procedure. Otl_erwisv,, we wi]i_ _invest very much to gain

to have a low gain, compared to established and the well-trained

procedu cos.

DiCK 3RAY (NASA) - In t-,,_ard t:o ]ookin: 3 at: airy algorithm F_or

re-veery, whether it b,:' t.,_;.e:_,f[oi: landlady, tl_at using the bat_:h

process at the comL)ul:et to compare one with the other is very

548 ORIGINAL PAGE IS

OF POOR QUALITy
valid, but I think it should also be assumed one with a whole

matrix of delay conditions--assumptions of pilot delay and

response. Certainly, even the present warning systems are very

likely to have you start your recovery 15 knots below your

initial speed or well below even normal approach speed. I think

as these conditions exists, you'll find that the difference

between the optimum path and any of the simpler paths gets

smaller and smaller. So I just recommend that anybody doing a

study certainly consider a large range of delay times.

KIOUMARS NAJMABADI (Boeing) - I would just like to make a

remark about delay. The study was done by Angelo Miele in fact.

He found that with a delay of more than 4 seconds, there was

absolutely no difference between the optimal trajectory and the

other suggested strategies for the takeoff case.

PAUL CAMUS (Airbus Industries) - Does that hold true for the

approach case?

KIOUMARS NAJMABADI (Boeing) - He hasn't done any study on

that and we are in the middle of doing that study ourselves.

549
HERB SCHLICKENMAIER (FAA) - [Reading from John Chisholm's

question:] A question was raised as to the ability to detect weak

microburst echoes in the presence of ground clutter as viewed by

a weather radar in a landing airplane.

The obvious next question is - what is the lowest altitude

that can be viewed with such a constraint?

"The answer appears to be that by a combination of

appropriately programming tilt angle and range gating the data it

is possible to insure no main beam ground illumination and yet

view 400 feet. altitude outflow, to ranges of a mile, i.e. 30

seconds advance warning over the reactive type systems.

Following this line of reasoning, 2 mile range is achievable,

with altitude coverage down to 750 feet, and three miles, with

altitude coverage down to 1200 feet. In other words ground

clutter appears to be manageable.

"The question of the magnitude of ground clutter at low

grazing angles, i.e. 3 to 0, is still controversial. For this

reason the data NASA is arranging to be obtained is highly

important."

If one assumes a clutter reflectivity of -20db, (Evans used

-10db for low grazing angles, TDWR uses a mean value of -40db)

and a dbz of +10db the signal/clutter ratio becomes -50db, a

difficult signal to clutter ratio to handle, especially from a

moving platform. However, if only side lobes illuminate the

ground the signal to clutter become 0db which is much more

manageable.

John, anything you need to add to that?

JOHN CHISHOLM (Sierra Nevada Corp.) - If anybody is curious,

I have one view graph that will illustrate this concept of

program tilt. This was a question that Jim Evans raised

yesterday as regards to the difficulty of picking out weak echoes

in heavy ground clutter. And his argument, which is valid, is

that if you illuminate the ground with the main beam you are down

in the -50 -60 db signal to clutter ratio which is at the limits

of what you could get with a good doppler processor or good radar

because of the stability of components. The argument, or the

discussions that we have had with NASA on this subject in effect

state, why illuminate the ground just as you come in for a

landing, which is the worst case, you just tilt your antenna beam

up and you program the range at which you are looking. And for a

mile ahead you get your coverage down to the magic out flow

region of 400 feet and as you tilt it up you get coverage out to

3 miles the altitude goes to 1200 feet and you can argue whether

that is a good valid outflow region, but you can also argue that

you will get very useful data.

55O
EMEDIO BRACALENTE (NASA Langley) - I would like to comment a

little bit on this subject. This is a great idea and it is one

we plan to evaluate extensively. This is one approach for

reducing the large clutter signals, obviously, since the signals

are distributed "spectrum-wise", other techniques of signal

processing can also be applied, even for the case when the beam

is pointed straight down the glide slope, to reduce the clutter

signals. So, there are many approaches, to possibly solving the

problem, that need to be addressed. That is part of what we are

trying to do. I think that it's a significant problem, and we

need to understand it and hopefully reach that point where we

will be able to indicate ways of managing the problem with

clutter.

551
DAVE HINTON (NASA Langley) - We don't have a view foil on

this one, the question was from Bob Ireland. He says, "given that

most wind shear accidents have been preceded by excessive

lowering of the nose or allowing the nose to drop, and given that

your flight path guidance was not clearly successful in the wind

shear modeled afeeter real world conditions; Do you recommend any

aggressive nose lowering Jdl__b__Jlb99/]99 of guidance, i.e.

today?"

Some things I couldn't get into in the discussion, in

looking at the scattering of data, part of the reason for that

scatter is that the research pilots wanted to vary their gain

somewhat from run to run. Fly more aggressively or less

aggressively. The success of that guidance was dependent on

close adherence to the pitch schedule that was programed. In

some cases the pilot decided that if lowering the nose to i0

degrees is good then maybe I'll lower it to 8 degrees and that

will be even better. And that put the airplane in the ground.

Here's the view foil. In other cases, and there were numerous

cases where the pilots, and perhaps even myself sitting in the

right seat, thought we had successfully penetrated the shear,

thought everything was looking good, the trends were good, but a

few seconds later we are on the ground wondering what happened.

The point is that the middle of the shear is a very confusing

place for a pilot to be, and to go back to the answer I've

written down here. The flight path angle guidance looks like the

way to go. It's the direction to pursue. I would not take the

guidance I have now and advise anybody actually installing that,

as is, in an airplane in an operational environment. So it was

the best, and showed the most promise of all the options tested,

but it is not a technique, and this is my belief, that a pilot

could reliably fly in the absence of guidance. The pitch that

you would need at any particular instant is going to depend on

the necessary flight path angle at that point, the airplane's air

speed, what the wind is doing to you. The success of that

technique depends on closely following that pitch, and on todays

flight decks you do not have flight path angle information

available. If you try to get that information from looking at a

vertical speed indicator, you are going to have lags, especially

if you have someone else reading the vertical speed to you. Same

with the radar altimeter. You'll have lags just from someone

reading that to you, uneveness in the ground, that sort of

thing. Any excessively low nose attitude, pitch attitude, will

put the airplane on the ground. Rotating the nose back up, to

flare, too late can put the airplane on the ground. So, I can

not advocate aggressively, and I'm talking about a take off case

now, aggressively putting the nose back down. If you try to do

that now, we would have to give the pilot a procedure that would

depend on where he is. We would say, okay if you are above 500

feet on approach, for example, do this. If you are below a

certain altitude on approach do something slightly different. If

552 ORIGINAL PAGE tS

OF POOR QUALITY
you've just lifeeted off, there is a third action to take. If

you have lifeeted off and you are climbing through 300 feet there

is yet another target pitch to go to. And I don't believe you

could train to that. You cannot give the pilot half an hour of

training each year and then expect a line crew to go out an

reliably follow that. So, does that answer the question? He's

not here. Well, I guess it does.

DAN LABRIOLA (Technical AirServices) - Just as an aside, I

know this debate is going to continue for some time, guidance

versus no guidance. But, I would like to reiterate that at least

in all of my experiences and everyone else I know, you can still

do better with a good guidance system then you can without.

Sometimes that emphasis seems to be getting lost in the debate.

So I will mention it again since it makes me feel better to say

it. Thank you. o

553
FRED PROCTOR (MESO) - This question is from Joe Youssefi

(Sperry Honeywell). "Why are the peak outflow winds derived from

model less than the actual data for altitudes above 300 meters?"

The slide that Joe is referring to is the vertical profile for

the peak differential outflow velocity for the Denver 30 June

simulation (see presentation). The simulated profile is given by

the heavy solid line, but also shown are the observed profiles

for the JAWS averaged and the JAWS 5th of August cases. There

are several possible reasons why the simulated profile indicates

weaker outflow speeds above 300 m than indicated in the JAWS

profiles. First, profiles from different dates are being

compared. Another possible reason is that the model simulation

assumes an axisymmetric microburst, while many of the JAWS

microbursts were, in fact, asymmetric. Lastly, the JAWS profiles

are not actual data, but are derived data from Doppler radar

measurements -- and therefore may suffer some inaccuracies such

as due to ground clutter, beam-width averaging, and data

filtering.

The second question Joe Youssefi asks is "What physical

elements cause multiple vortex shears such as in the DFW flight

recorder data?" Well, I can only speculate there but, if you are

familiar with the Delta 191 incident, there were some very strong

oscillations in the vertical velocity just before the plane

crashed. Some people have attributed these oscillations to

multiple vortex rings, although I an_ not convinced by this

explanation since the oscillations were pronounced only in one

side of the microburst. However, I have seen strong vertical

oscillations in some of my model simulations when a shallow,

ground-based stable layer is present. Thus, another possible

explanation for the vertical oscillations experienced by the

Delta 191 could be due to gravity wave oscillations. As a

downdrafeet penetrates through a stable layer, it will set up

gravity oscillations, somewhat analogus to dropping a rock into a

pond and seeing the waves propagate outward.

Next, I will attempt to answer several questions addressed

to the general audience by Bob Otto. "What is the extent of

spatial asymmetry in microbursts? And do we have sufficient data

to assess the asymmetry?" In the JAWS program a large portion of

the microburst were detected as having asymmetric outflows; I

can't remember the exact percentage, but on the order of 60-70%

0id show at ]east some asymmetry. However, in the FLOWS program,

a much smaller percentage of the microburst outflows were notably

asymmetric; 85% were reported to have a least near symmetry. So

in some areas or cases the axisymmetric assumption may not be a

bad assumption. I suppose a good question to ask is under what

conditions favor symmetrical or nearly symmetrical microbursts

versus those conditions which favor microbursts being skewed from

symmetry. The condition which probably has a strong influence on

the symmetry of asymmetry of a microburst is the environmental

554

,uz,::.... .";AL PAGE IS

OE POOR QUA/4IT_
ORIGINAL PAGE I_

OF. POOR QUALITY

4b

winds ill which the microburst occurs. If microburst occur in

environments which have weak winds and weak vertical wind shears

then they may show a high degree of symmetry. The DFW microburst

was probably a good example of this situation. Now, in cases

where there is moderate to strong ambient winds and ambient wind

shea_, the downdrafeets are going to transport momentum downward

toward the ground which will skew the outflows from symmetry. In

the future we plan to investigate the symmetry question using our

three-dimensional model.

In the second question that Bob Otto asks is "If there is

significant asymmetry in microburst phenomena, then what effect

does this have on aircraft aerodynamics? Qualitiative,

conceptual trends are desired." I'll let someone who is an

expert on aerodynamics answer that question.

HERB SCHLICKENMAIER - Before we ask Bob Otto, let the record

show that all eyes went to Roland Bowles. Bob.

BOB OTTO (Lockheed) - The intent of the question is, really

is there any special types of algorithms that need to be

developed because of a microburst being asymmetric as opposed to

it being symmetric. I am addressing the question from the _oint

of view of a sensor technologist who wants to build a system.

And I am looki_g for things in the phenomeno]ogy of microbu_sts

which will help me determine the requirements for a sensor.

ROLAND BOWLES (NASA Langley) - Let me ask the question

back. Do you feel this is a more significant problem than the

ability to scan to get vertical wind information and what does

th ,_ <emote sensor technology people feel about the scanning

opportunities with pulse doppler systems whether they be light or

microwave?

BOB OTTO (Lockheed) - I think the question that you gave

back to me is a subset of the question that I am asking. I have

concern that whatever algorithms or whatever procedures or

whatever requirements eventually get developed for a particular

sensor, that I wonder if they are going to be genera] enough to

handle all cases or are there going to be some specific things

which will be anomi]ies. You see, what: I am really looking at: is

a,]y sensor guy is goi_g to develop something based upon what the

average, requiremet]ts are. Or perhaps a nominal cases, _n some

cases he may even go to a pathological case. What I am trying to

get at is, are there pathological cases here that we ought to be

aware of up front? What percentage of the time do we meet those

types of things? Or are things relatively benign?

ROLAND BOWLES - Okay, I']] answer it in a general way. What

we want is, the winds in the vertical [,lane? I don't know of ai_y

cases where we have seen cross wind shear that has caused an

accident. So you know you are largely looking at what is along

555
my flJgbL-path-extended and above an(] parlicu]ar]y below that

flight path in a vertical plane. I do thit_k that the remote

sensor people have to give serious coi_sJderatJon to looking at

what you can do with vertical scanning. But, the asymmetrical

aspects--I don't see a problem. We discussed this among some or

us recently, I do,l't see a problem of where asymmetries upset the

situation if you've got the sensor on the airplane. If the

microburst is elongated, orthogonal to your flight path, that is

what you are going to see. You are ,going to see a small wind

shear. If it is elongated along the flight path, that is what

you are going to see, a pretty significant shear over a

characteristic dimension that may be hazardous. So I don't see

the assymmetry question as critical when the sensor is on the

airplane to the same extent J f the sensing device is ground

based.

RUSS TARG (Lockheed) - Roland asked an interesting question

with regard to assymmetry in the microburst more significant for

a system designer than the ge_leval question of scanning. I

thought Sam Saint's questions this afeeternoon were very apropos

to that. It may be that as you examine the interplay of the

phenomezlology of the microbut-st and the flight dynamics that you

will decide that you can establish a significant threat from the

"performa_]ce-increasing" portion of th,<_ microburst so that

con<,eivably it will not Im,_ n,:::cessary to do scanning. That is a_:_

you come into a microburst such as the one at Dallas Fort Worth

and you look out in fro,l[: of i:he aircrafeet a,Id see that you are

going to pick up 20-40 knots unasked for performance increasing

head wiled, thd[ may be such a pathological (case) outside the

envelope head wind that you really doi]'t want to 9£:t any more

in[ormation and that you will take a missed approach at that

point without determiniJlg what is inside the funnel or whether or

nok iJl addition] to the bizzar head wir_ds you are runiling into

Lhbre Js also a vertical com[_onent.

So I think izhere is a s:,gnificant f]]glLt dyn_m.ics question

i:bat may allow us to use these precursor wii_,]s as a sig_atore of

a threat without a_y further ado. That is a proposal obviously,

that is not a considered answer to your _ question, but based on

Sam's comments I think that that is a significant worthwhile ,aro_

for us to look at.

JiM MOORE (NCAR) -. Lot me, oFFer a few obs,_rv,TtJons that

we've had, l:hat I have specifically had in th(. tc)w,_r and I think

thaL a few others might halve s,;<'n as well. dust to give some

input to the technologists who are trying to deal with something

other- than just the always symmetric case. Assymmetry at ]east

in the bursts in Colorado se_m to be pretty common, in fact, I

think the figures werc_ quoted quite accurately. A l_t: of that _s.

(It]vail by l:ho facl; tlla[ tlie w.i_c]r, c:oilljng off the Rockies are a

lot Ld_,tet r_<. than whatever Js at th,__ ",u_-face so you ]et this

natural like a titled roia shafeet type of effect and you expect

8

556

_)_ P.OO_R QUALIT_
ORIGINAL PAGE IS

_OF_POOR QUf_LITY

winds on one side of that to be quite a bit stronger than they

are on the other. So assymmetry at least in the high planes of

the United States is probably more common than symmetry. The

next thing is the phenomenon that I noticed most recently

visually at Stapleton during the event: that I showed a slide of

this morning where microburst moved across the airport. The

microburst went through a pulsing phenomenon where it seemed to

dump or it seemed to occur with a down drafeet you would get the

curl of dust by the way, it was only one side as well, that

doesn't mean it wasn't symmetrical but there was no evidence of

dust on one side where there was a lot of dust on the other. So

there is a pulsing phenomenon and it died away and then a few

minutes later it was back and as the cloud moved essentially down

wind, you got a very distinctive feeling of a pulsing

phenomenon. Yet another, is something that we have dealt with

now 3 or 4 times Jn fact, in 1984 during the CLAWS (Classify,

Locate, and Avoid Wind Shear) program it proved to be one of the

most damaging to airport facilities that we had. It was not an

isolated symmetric or asymmetric microburst, it is something that

we call a Microburst Line, which is a real interesting bird. It

is almost like it is a line of verga that produces a down drafeet

along a very long axis, a quite long axis so you have divergence

on either side of art essentially fairly straight: line. That did

some remarkable damage, physical damage to the airport itself and

we shouldn't ignore some phenomenon like that. I'm not

indicating that the instrumentation necessarily has to be

changed, but I'm trying to give you a feel for what we see with

our eyes, what we see visually when we are sitti;Ig in a tower and

can observe this. There is one last thing I would like. to say

with respect to Russell's comment and a comment offered earlierc<...._erning reactive instrumentation as soon as you see inc,'easing

headwinds. And that is that if you have a scenario of a simple

cold front or in the high plains another very common thing is a

gust frost one would have to be real careful about a real high

false alarm rate by responding only to an increase in energy

because, unless there is something behind that, the_:e is

something else, the occurrence, the preponderonce of a gust front

phenomer_on in Colorado ]s quite regular during the summer. And

in and of itself it is not particularly hazardous to aviation

because of the nature of the impact and no particular following

wind behind it to adversely effect aircrafeet performance. I

think that is all.

HERB SCHLICKENMAIER - We just rapL_ed up qu,_st.[on th_:ee as

well.

557
KIOUMARS NAJMABADI (Boeing) - I would just like to make a

remark that we at Boeing are also involved in evaluation of the

sensors before looking as well as hazard index evaluation to find

out what is the proper index for hazards, under the same

contract.

558
HERB SCHLICKENMAIER (FAA)- This is a question posed to me

from Dan Labriola from Tech AirService Inc. "What is being done

to assist the operators with smaller training departments to

implement the training aid?"

I'll be happy for anyone else to chime in at some point but

let me give you some preliminaries. You'll remember in the

Integrated Wind Shear Program Plan, that we do talk to

transfering the information from the 121/135 community into the

91 (the general aviation) community. At this point we are

looking at some different approaches for evaluating that.

Looking at the general aviation fleet compared to the air carrier

is looking at very large number of manufactured airplanes and

pilots as compared to a relatively few number of airplanes in the

121 side. So at this point we are looking at some evaluations to

transfer the information. Does that get to some of the point

Dan? Or does anybody else have something to contribute to this.

DAN LABRIOLA - Well, you know the reason I asked that Herb

is because we are trying to help some of the really small

carriers and you know the people out in the boon docks in third

world. People who are interested in this thing but don't really,

some don't, most don't know if its existence even though they

have been sent copies of the aid and it is rare that you can find

a small carrier who recognizes the significance of what is going

on. You know the general feeling out in the community outside of

our environment you know, we are used to talking to United,

American, and Delta and people who are really on top of this.

The overwhelming number of folks out there have no idea what is

going on. Have no idea that there are things they can do in the

interum to improve their likelihood of surviving one of these

encounters. I mean, I am one person I am certainly not going to

change that and it seems like once again it takes an effort maybe

on the part of this whole group I don't know, to get to that.

But, there seems like there is something missing in this.

HERB - Questions, points? As I mentioned earlier, we are

not there yet Dan. I think through some conserted effort and

through some response back into the program maybe the

recommendations could come in for us to look at that.

559
ROLAND BOWLES (NASA Langley) - Jim Mitchell of Boeing asked

a question of me. "In noting that stickshaker speed is increased

in heavy rain do you mean that stickshaker should activate or

will it activate at higher speed, stall warning system doesn't

know that it is raining. It is my understanding, stickshaker is

activated on angle of attack. So for fixed configuration,

weight, and lift drag polar, that will occL_r at some speed. If

you change the lift drag polar it will occur at a different

speed."

BUD LAYNER (NTSB) - Along the same line, has Earl's research

shown where the stall margin is reduced at stickshaker activation

with the different "CL-ALPHA" curve?

ROLAND BOWLES - No.

BUD LAYNER (NTSB) - Is that no, or don't know?

ROLAND BOWLES - No he's not prepared to reveal that to

anybody. There is a second question from Jim Mitchell of Boeing.

"What is your source for the statement that 6% of airplanes now

have wind shear systems? 6% of which airplanes?"

My source Jim, is Boeing. But, more recently upon further

research the answer has changed and it now looks like that 4% of

major and national aircraft by the end of 1987, will be wind

shear equipped. And that is pretty solid data from your people

in Seattle.

JIM MITCHELL (Boeing) - That doesn't necessarily mean that

all of the airplanes we've got equipped have activated the

system, that is important for people to understand that a lot of

airlines are waiting till they have retrofitted their entire

fleet before they activate. Especially those that incorporate a

guidance system also. It is a crew training problem. That is

something to be aware of.

ROLAND BOWLES - That posses an interesting question in terms

of what we heard this morning. That means that some may not be

equipped for four years. If that is a strategy that is going to

be followed then safety may be compromized.

SPEAKER - I'd like to ask the French what is the number for

the French airplanes.

PAUL CAMUS (Airbus Industrie) - All our aircraft are

equipped with airborne windshear systems. By the way, they are

equipped from 1974.

HERB SCHLICKENMAIER (FAA)- Sam, you've become a speaker.

This is from Jim Mitchell (Boeing) for Sam Saint: "How will your

560
warning energy gain or energy loss on the runway deal with the

dangers of an aborted takeoff? With active winds on the runway,

"V-One", may be reached further down the runway than predicted.

Therefore, even if airspeed is below Vl, there may not be room

lefeet to stop."

SAM SAINT (SFIC) - The concern about triggering an abort at

the dangerous point of the "go no-go" point where the runway

length is critical, has got to be a real concern. And I can

understand the worry of a manufacturer at the possibility of

being held responsible in a liable suit if the airplane received

a warning at the critical point and then wound up in a smoking

heap at the end of the runway. That is a very real concern. And

I thought a long time about this before giving my inputs to

SafeFlight on this, and my position became and has strengthened

with everything I've learned since. The greater responsibility

is to have a computer on board the airplane that knew that United

633 should abort the takeoff while he had a lot of runway still

in front of him, but withheld that information from the pilot.

And this was one of the things that caused me to go back through

the accident record to find out if indeed any of the experiences

we've had to date happened at the critical "go no-go" point with

a marginal situation for the pilot. And as I indicated in those

eight accidents, the warning would not have come even close to

that critical time in any one of the accidents we looked at.

Now, I point that out to SafeFlight and advising them and I acted

very much as an individual on this. When I even walk in the door

at Safe-Flight, I take my Safe-Flight badge off and put it aside

and talk from the point of view an airplane pilot who flew

_ir_lanes all the way from the DC2 up to the 747; did a fair

ai_....nt of engineering test flying; and I think I know how pilots

act and how they think, and how what we can expect from the

pilots at the low end of the spectrum. Because an airline pilot

is not a standard item having a perfectly standardized

performance response, and I conclude that the pilot in this case

is going to have to make a decision anyway. United 633 rolling

down the runway, the captain testified that he thought of

aborting when the airspeed indication hung up and then changed

his mind and kept on going when the airspeed indicator picked

up. No matter what happens during that takeoff roll even at the

critical "go no-go" point, the pilot is faced with a necessity to

make a decision. I think it borders on the immoral (that is

probably not the right word) to withhold from that pilot who has

to make the decision anyway, to withhold from him information

that the computer knows very well as to what the ]evel of the

threat actually is.

JIM MITCHELL (Boeing) - I think the issue is so complicated

on the runway (if given the current generation of wind shear

alerting systems) you are really talking about taking the "go

no-go" situation decision away from the pilot almost. If you're

going to, there ought to be a window where you either take into

561
account in the alert of, if you reach a certain speed on the

runway then you are going to inhibit that alert because if he has

made the decision to go right then, it J.s probably not going to

help him until he is up off the ground, then you can alert? Or,

are you going to include in your alert algorithm a computation

based on a known length of the runway and friction coefficients

and all that to make a judgement as to whether you should

recommend an abort? I mean, what is the crew action going to

be? I think that is a really complicated issue.

SAM SAINT (SFIC) - Anyone who has ever operated in command

of an airline airplane knows that there is no way you can give

the pilot out of any computer that now, or in the future an

arbitrary judgement that takes that judgement out of the hands of

the pilot. You just can't do that. What we are talking about

here is giving the pilot the benefit of a computers measurement

of what is actually happening. The warning is telling the pilot,

look the outside environment is at this moment exceeding

acceptable limits, _n the speed with which the head wind is going

to a tail wind or visa versa. But there is no way that that

computer can tell the pilot who is in command of that airplane

that he now must stop thinking and abort. Okay? The pilot of

that airplane gets paid pretty well for using his judgement. And

he is not going to pass that judgement off to a computer. But he

would like to have the help of that computer in knowing what is

actually going on.

DICK BRAY (NASA Ames) - I jusk wanted to quickly bring up

another technical point, that while you are rolling on the runway

up to 60-70 or 80 knots your system is measuring a W dot. and wind

rate of change. While the airplane is going at those lower

speeds it is going to see that rate of change as a fairly low

value, a lot lower value tharl if you are steaming by at 140. So,

it might be that your normal threshold is going to be way too

high to recognize. I wanted to bring up that point. You _Jro

going to have to do a little adjustment on the thresholds in that

condition.

SAM SAINT (SFIC) - The_ has to come a point Dick, at which

you say the air speed ha_ now reached c. level of reliability that

we can feed it in the computer. Now, SafeFlight said that speed

should be 80 knots and I've heard others say that that should be

down to 60. And I've talked this problem with Joe Yoeseffi and

some other people, and I fully understand that you have to have

stable air speed information to compare to _he inertial

acceleration in order to get a valid ipdica[ioI] of what is

ha[_pening.

SPEAKER - I had a similar question in that some of the

reading I've been doing indicates that (pause) my question sais,

it is a comment really. One of t]le speakers yesterday pointed

out that the takeoff microburst can be more hazardous than the

562
landing one due to high gross weights, low potential energy,

etc. I have seen some proposals that call for activation of the

sensor or warning system late in the takeoff roll or afeeter air

borne and in my opinion that is too late and systems must be

required to operate for brake release. Now, I know there are

some technical problems, but we should be shooting at developing

a system that gives us this information as soon as possible on

the takeoff roll.

KIOUMARS NAJMABADI (Boeing) - Has there been any

modification to Airbus detection systems since 1976. If yes, how

many?

PAUL CAMUS (Airbus Industrie) - All our airplanes which have

been in service from 1974 have been equipped with two basic

systems. The first one, the "Alpha-Floor Protection System",

takes care of wind shear. The other system is a "Speed Reference

System", which can be used on takeoff and go around phase. It is

a guidance system which feeds the flight director bars. Ill fact,

for the time being, we have no detection on takeoff. But what we

do really, is to provide an adaptive control which is able to

take care, automatically, of any aircraft performance

degredation. The only thing which is missing for the time being

is a detection system on takeoff. But just to cope wihh

situation where we takeoff with derated thrusts. This is because

the pilot has to apply immediately the full maximum takeoff

thrust. And as a matter of fact, it appears from our experience

on our simulators with many different pilots, that the

application of thrust on takeoff is not obvious and there are

some pilots who miss applying full thrust to cope with wind sheer

enco_iter. From that time, we have not yet implemented

additional modification. However, we have improved design in

various areas. First, guidance on takeoff, an improved detection

of the vertical wind component. As you may know, the last

generation Airbus airplane which is the A-320 has a flight

control system concept. And on that airplane we also have a

specific feature which is to protect the aircraft flight

enveloped against excessive angle-of-attack. And therefore, th:_i_

means in a wind shear encounter the pilot is able to apply, as

required, full stick-back and the computers will regulate the

maximum angle of attack to obtain the maximum possible lift.

This feature is very important because the pilot is sure that he

will not endanger the aircraft at high angle of attack. I hope

that answers your question.

563
LIST OF ATTENDEES

FIRST COMBINED MANUFACTURERS' AND TECHNOLOGY

AIRBORNE WIND SHEAR REVIEW MEETING

H. Patrick Adamson

Turbulence Prediction Systems

4876 Sterling Drive

Boulder, CO 80301

303/443-8157

Jean Louis Bonafe

Aerospatiale A/DET/SY

316, Route de Bayonne 31

31060 Toulouse,

FRANCE

33 61 93.58.06

Bernard Ades

DGAC/SFACT/TU

36 rue du Loune

75 ODA Paris,

FRANCE

33142334465

Ernest Admiral

Douglas Aircraft Company

3855 Lakewood Boulevard

Building 202-29

Long Beach, CA 90846

213/593-9599

Orville J. Alitz

Rockwell-Collins

400 Collins Road

NE 124-111

Cedar Rapids, IA 52498

319/39_-3885

Prof. Ernest Baxa

Clemson University

Electrical and Computer Engineering

Clemson, SC 29634

803/656-5901

Ken Beach

Kollsman

i MO.7-1

220 DW Highway

Merrimack, NH 03054

Edmond Boullay

Embassy of France

DGAC/SFACT Representative

4101 Reservoir Road, NW

Washington, DC 20007

202/944-6054

Dr. Roland Bowles

NASA Langley Research Center

Vehicle Operations Research Branch

Building 1168, MS 156A

Hampton, VA 23665

804/865-3621

Emedio M. Bracalente

NASA Langley Research Center

Antenna and Microwave Research Branch

Building 1299, MS 490

Hampton, VA 23665

804/865-3631

James R. Branstetter

NASA Langley Research Center

FAA - M/S 25O

Hampton, VA 23665

804/865-4595

Richard S. Bray

NASA Ames Research Center

MS 211-2

Moffett Field, CA 94035

603/886-2562 415/694-6002

Dr. Hans-Juergen C. Blume

NASA Langley Research Center

MS 490

Hampton, VA 23665

Charles L. Britt

Research Triangle Institute

NASA Langley Research Center

Hampton, VA 23665

804/865-3631 804/865-3631

565
Prof. Gary S. Brown

VPI & SU

Departmentof Electrical Engineering

Blacksburg, VA 24061

703/961-4467

GabeBruno

Federal Aviation Administration

8613Kerry Lane

Springfield, VA 22152

202/267-3830

ThomasG. Campbell

NASALangley ResearchCenter

Head,AMRB

MS490

Hampton,VA 23665

804/865-3800

Paul Camus

Airbus Industrie AL-EE-A

i RondPoint Maurice Bellonte

31707Blagnac,

FRANCE

33 61 93.31.34

DaveCarbaugh

Boeing CommercialAirplane Company

P.O. Box 3707

MS66-25

Seattle, WA 98124

206/237-7286

Dr. ToddA. Cerni

OPHIRCorporation

7333W. Jefferson

Suite 210

Lakewood,CO 80235

303/986-1512

Dr. Martin Cervenan

University of Alberta

Alberta Laser Insitute

9924 45th Avenue

Edmonton,Alberta, TGE5Jl

CANADA

403/436-9750

William D. Chandler III

CrenshawInternational, Inc.

1199N. Fairfax Street

Suite 700

Alexandria, VA 22314

703/548-2544

No-Pen Chang

FWG Associates, Inc.

UTSI Research Park

Building #i

Tullahoma, TN 37388

615/455-1982

John Chisholm

Sierra Nevada Corp.

4900 Energy Way

Reno, NV 89502

Myron E. Clark

Federal Aviation Administration

AFS-210

800 Independence Avenue, S.W.

Washington, DC 20591

202/267-3730

Ralph Cokeley

Lockheed Aeronautical Systems Company

Dept. 98-12, Bldg 608, Plant i0

I011 Lockheed Way

Palmdale, CA 93550

805/272-2452

Walter S. Coleman

Air Transport Association

1709 New York Avenue NW

Washington, DC 20006

202/626-4015

Ron Crabill

Federal Aviation Administration

FAA/ATO-324

800 Independence Avenue, SW

Washington, DC 20591

202/267-9337

566
Dr. J. F. Creeden

NASA Langley Research Center

Director for Flight Systems

Hampton, VA 23665

Vic Delnore

PRC Kentron, Inc.

NASA Langley Research Center

MS 490

Hampton, VA 23665

804/865-3631

George Ellis

British Aerospace Plc

Civil Aircraft Division

Hatfield

Herts, AL i0 9TL

ENGLAND

(0) 7072 62345

Carl W. Erickson

Boeing Commercial Airplane Company

P.O. Box 3707

MS 47-31

Seattle, WA 98124

206/655-8224

James Evans

MIT Lincoln Laboratory

P.O. Box 73

Lexington, M=% 02173

617/863-1804

C. Mikel Gale

American Airlines, Inc.

M&E Center MD #208

P.O. Box 582809

Tulsa, OK 74158

918/832-2188

Dr. Brian J. Gallagher

Delco Systems Operations

MS IAI0

P.O. Box 471

Milwaukee, WI 53201

414/768-2132

John F. Garren

NASA Langley Research Center

MS 153

Hampton, VA 23665

804/865-3953

AI Gleske

Flight Safety International

655 15th Street, N.W.

Suite 300

Washington, DC 20005

202/639-4066

J. Howard Glover

Sundstrand Data Control, Inc.

15001 N.E. 36th Street

P.O. Box 97001

Redmond, WA 98073

206/885-8407

George A. Greer

PRC Kentron, Inc.

303 Butler Farm Road

Hampton, VA 23666

804/865-3585

Robert W. Hall, Jr.

Air Line Pilots Association

Engineering and Air Safety DepartmEnt

P.O. Box 1169

Herdon, VA 22070

703/684-4205

R. John Hansman

MIT

Dept of Aeronautics & Astronautics

33-115

Cambridge, MA 02139

617/253-2271

Steven D. Harrah

NASA Langley Research Center

AMRB

Hampton, VA 23665

567
George C. Hay

Federal Aviation Administration

FAA/ADL-2A.2, Room 836B

800 Independence Avenue, SW

Washington, DC 20591

202/267-3021

R. C. Hayes

Honeywell Inc.

Sperry Commercial Flight Systems Group

5353 West Bell Road, M/S 51 EAV

Glendale, AZ 85308

Tom Heinzer

SIMU FLITE Training International

P.O. Box 619119

DFW Airport, TX 75261

800/527-2463

David A. Hinton

NASA Langley Research Center

Vehicle Operations Research Branch

Building 1168, MS 156A

Hampton, VA 23665

804/865-3621

R. Milton Huffaker

Coherent Technologies, Inc.

3300 Mitchell Lane, Suite 330

Boulder, CO 80301

303/449-8736

Bob Ireland

United Airlines Flight Center

Stapleton International Airport

Denver, CO 80207

303/398-4553

William R. Jones

NASA Langley Research Center

AMRB

Hampton, VA 23665

Dr. Daniel Labriola

Technical AirServlces, Inc.

1020 East John Street

Seattle, WA 98102

206/325-3000

William G. Laynor

National Transportation Safety Board

800 Independence Avenue, S.W.

Washington, DC 20594

202/382-6610

Dr. Alfred T. Lee

NASA Ames Research Center

Aerospace Human Factors Research Division

Moffett Field, CA 94560

415/694-6908

Gary Lohr

NASA Langley Research Center

MS 156A

Hampton, VA 23665

804/865- 3621

Carroll D. Lytle

NASA Langley Research Center

AMRB

Hampton, VA 23665

Anne Mackenzie

NASA Langley Research Center

AMRB

Mail Stop 490

Hampton, VA 23665

804/865-3631

Connie L. Manor

NASA Langley Research Center

PRC at AMRB

Hampton, VA 23665

a

568
4

Rosemarle L. McDowall

Computer Resource Management, Inc.

FAA Technical Center

Building 270

Atlantic City Airport, NJ 08405

609/484-6911

Dr. Burnell T. McKissick

NASA Langley Research Center

MS 156A

Hampton, VA 23665

804/865-3621

Peter Melklem

British Embassy

Civil Aviation Attache-Safety

3100 Massachusetts Avenue, NW

Washington, DC 20008

202/463-7530

W. Edward Melson, Jr.

NASA Goddard Space Flight Center

Wallops Flight Facility

Wallops Island, VA 23337

804/824-1306

Mark W. Merritt

MIT Lincoln Laboratory

P.O. Box 73

244 Wood Street

Lexington, MA 02173

617/863-5500

Roger Millins

British Aerospace Plc

Civil Aircraft Division

Hatfield

Herts, AL I0 9TL

ENGLAND

(0) 7072 62345

James E. Mitchell

Boeing Commercial Airplane Company

P.O. Box 3707

MS 01-82

Seattle, WA 98124

206/342-2412

569

James Moore

NCAR

Deputy Manager, Field Observing Facility

P.O. Box 3000

Boulder, CO 80307

303/497-8816

Samuel A. Morello

NASA Langley Research Center

MS 153

Hampton, VA 23665

804/865-3953

Stephen V. Morrison

Federal Aviation Administration

800 Independence Avenue, S.W.

Washington, DC 20591

202/267-3736

Tom P. Murphy

RJO Enterprises, Inc.

4500 Forbes Boulevard

Lanham, MD 20706

301/731-9746

Kioumars Najmabadi

Boeing Commercial Airplane Company

P.O. Box 3707

MS 9W-38

Seattle, WA 98124

206/277-4280

Robert G. Onstott

Environmental Research

Institute of Michigan

P.O. Box 8618

Ann Arbor, MI 48105

313/994-1200

Rosa M. Oseguera

NASA Langley Research Center

MS 156A

Hampton, VA 23665

804/865-3621

R. G. Otto

Lockheed

3251 Hanover Street

Palo Alto, CA 94304
Richard D. Page

FAATechnical Center

FAA/ACT-IO

Atlantic City Airport, NJ 08405

William F. Petruzel

Federal Aviation Administration

FAA/APF-430,Room727

800 IndependenceAvenue, SW

Washington, DC 20591

Greg Piesinger

Honeywell Inc.

Sperry CommercialFlight SystemsGroup

5353WestBell Road, M/S 51 EAV

Glendale, AZ 85308

Fred Proctor

MESO,Inc.

28 ResearchDrive

Hampton,VA 23666

804/865-7800

Dr. Harold R. Raemer

Northeastern University

Dept. of Elec & ComputerEng'r

Room406 Dana, 360 Huntington Avenue

Boston, MA 02115

617/437-3035

SamSaint

Safe Flight Instrument Corporation

Shelter Harbor

Westerly, R1 02891

401/322-7505

Greg Salottolo

NTSB

800 IndenpenceAvenue, S.W.

Washington, DC 20594

202/382-6677

Pete Saraceni

FAATechnical Center

ACT-340,Building 201

Atlantic City Airport, NJ 08405

609/484-5577

570

Donald Schacht

Delco Systems Operations

MS IA21

P.O. Box 471

Milwaukee, WI 53201

414/768-2921

Matthew J. Schack

512th Military Airlift Wing

Attn: SE

Dover AFB, DE 19902

302/678-6807

Herbert W. Schlickenmaier

Federal Aviation Administration

FAA/APS-430, Room 727

800 Independence Avenue, SW

Washington, DC 20591

202/267-8530

Lyle C. Schroeder

NASA Langley Research Center

AMRB

Hampton, VA 23665

Amos Spady

NASA Langley Research Center

Mail Stop 156A

Hampton, VA 23665

804/865-3917

Leo D. Staton

NASA Langley Research Center

MS 490

Hampton, VA 23665

804/865-3631

George G. Steinmetz

NASA Langley Research Center

MS 156A

Hampton, VA 23665

804/865-3621

Raymond A. Stoer

Federal Aviation Administration

Northwest Mountain Region

17900 Pacific Highway South C-68966

Seattle, WA 98168

206/431-2117
J. L. Sweet

NASALangley Research Center

PRCat AMRB

Hampton, VA 23665

George N. Talley

512th Military Airlift Wing

Attn: SE

Dover AFB, DE 19902

302/678-6213

Russell Targ

Lockheed

Department 9701

3251 Hanover Street

Palo Alto, CA 94304

415/424-2436

Dan Vicroy

NASA Langley Research Center

Vehicle Operations Research Branch

5uilding 1168, MS 156A

Hampton, VA 23665

Nick Vretkis

NASA LaRC

MS 221

Hampton, VA 23665

Richard J. Walker

United Technologies Optical Systems

P.O. Box 109660

West Palm Beach, FL 33410

305/863-4275

Prof. David Watt

U. of New Hampshire

Dept of Mechanical Engineering

Kingsbury Hall

Durham, NH 03824

603/862-2555

Dr. Leonard W. Winchester, Jr.

Science and Technology Corporation

I01 Research Drive

Hampton, VA 23666

804/865-0467

Joe Youssefl

Honeywell, Sperry

Box 21111

Phoenix, AZ 85027

602/869-1557

Dr. J. Allen Zak

STX

28 Research Drive

Hampton, VA 23666

804/865-0214

571
Report Documentation Page

1. Report No.

NASA CP-]0006

DOT/FAA/PS-88/7

4. Title and Subtitle

Airborne Wind Shear Detection and

First Combined Manufacturers' and

Conference

7. Author(s)

I 2. Government Accession No.

Warning Systems -

Technologists'

3. Recipient's Catalog No.

5. Report Date

January 1988

6. Performing Organization Code

8. Performing Organization Report No.

Amos A. Spady, Jr., Roland L. Bowles,

and Herbert Schlickenmaier, compilers

9. Performing Organization Name and Address

NASA Langley Research Center

Hampton, VA 23665-5225

12. Sponsoring Agency Name and Address

National Aeronautics and

Washington, DC 20546

T5. Supplementary Notes

Amos A. Spady, Jr., and

Virginia.

Herbert Schlickenmaier:

Space Administration

10. Work Unit No.

505-67-41-03

11. Contract or Grant No.

13, Type of Report and Period Covered

____C__ference Publication

14. Sponsoring Agency Code

Roland L. Bowles: Langley Research Center, Hampton,

Federal Aviation Administration, Washington, D.C.

16. Abstract

The "First Combined Manufacturers' and Technology Airborne Wind Shear Meeting"

was hosted jointly by NASA Langley (LaRC) and the Federal Aviation Administration

(FAA) in Hampton, Virginia, on October 22-23, 1987. The meeting was co-chaired

by Dr. Roland Bowles of LaRC and Herbert Schlickenmaier of the FAA. The purpose

of the meeting was to transfer significant, ongoing results gained during the

first year of the joint NASA/FAA Airborne Wind Shear Program to the technical

industry and to pose problems of current concern to the combined group. It also

provided a forum for manufacturers to review forward-look technology concepts

and for technologists to gain an understanding of the problems encountered by

the manufacturers during the development of airborne equipment and the FAA

certification requirements. The present document has been compiled to record

the essence of the technology updates and discussions which followed each.

............. i

17. Key Words (Suggested by Author(sH . Distribution Statement

Microbursts Doppler Radar Unclassified - Unlimited

Wind Shear Infra-Red

Aircraft Hazards LIDAR Subject Category 03

19. Security Classif. (of this repoit) ...... 20. SecuiityClassif. (of this page) T21. No. of pages

Unclassified Unclassified _ 575 22. Price A24

NASA FORM 1626 OCT 86

F or sale by the National Technical I nformation Service, Springfield, Virginia 22161