SaUonaX Bureau of Shards

OCT 2 6 1962

^ecknlcai riot& 40-8

MEAN ELECTRON DENSITY VARIATIONS

OF THE QUIET IONOSPHERE

NO. 8 - OCTOBER 1959

J. W. WRIGHT, L R. WESCOTT

AND D. J. BROWN

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

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agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau's

unique competence is required. The scope of activities is suggested by the listing of divisions and sections on the inside of the back cover.

Publications

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NATIONAL BUREAU OF STANDARDS

40-8

SEPTEMBER 1962

MEAN ELECTRON DENSITY VARIATIONS

OF THE QUIET IONOSPHERE

NO. 8 - OCTOBER 1959

J. W. Wright, L. R. Wescott and D. J. Brown

Central Radio Propagation Laboratory

NBS Boulder Laboratories

Boulder, Colorado

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide .1 means for making available scientific data 1l1.1t are oi transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

I.. 1 ulr b) thr Superinlcndsnl "f Documenn 1 S GovCTnmrni Printing Washington .' • I > < P rati

CONTENTS

PAGE

I. Introduction o 1

II. Description of Basic Data 3

III. Description of Graphical Representation 6

IV. Discussion and Applications of the Data 7

Acknowledgments 9

References 10

Hourly Vertical Cross Sections Along

75°W Geographic Meridian 12

Isoionic Maps (150, 200, 250, 300, 350, 400 km;

Nmax, hmax, Scat, Shmax, Shinf) 36

Electron Density vs. Time Curves (N(t)),

(Newfoundland, Ft. Monmouth, WhiteSands, Grand Bahama, Puerto Rico) 47

in
ABSTRACT

The CRPL has initiated a program for large-scale

computation of electron density profiles from ionospheric

vertical soundings. Scaling is performed at field stations,

permitting computation of hourly profiles at the Central

Laboratory. These profiles are combined to form hourly

mean quiet profiles for each station and month. The results

of this program for the month of October are illustrated

graphically. This report is the eighth of a series illustrating the electron density variations in the mean quiet

ionosphere between latitudes 15 N and 50 N along the 75 W

meridian.

IV
MEAN ELECTRON DENSITY VARIATIONS

OF THE QUIET IONOSPHERE No. 8 - October 1959

J. W. Wright, L. R. Wescott and D. J. Brown

Central Radio Propagation Laboratory

I. Introduction

Part of the basic responsibility of the Central Radio Propagation

Laboratory is to gather ionospheric, solar, or other geophysical data

necessary in the pursuit of research leading to improvements in radio

communication and knowledge of the earth's upper atmosphere. The

existing network of ionospheric vertical sounding stations is an

important source of such data. Typically, the radio sounding data

directly provide observations of peak electron densities (corresponding to "critical" frequencies foE, foFl, foF2), data on Sporadic E,

and certain derived propagation data such as maximum usable frequencies or MUF factors (Smith, 1939).

In fact, the vertical sounding is potentially capable of providing

the complete electron density profile of the underside of the ionosphere

(i. e. , below hmax F2) and of providing a basis for extrapolation to

much greater altitudes. However, because a lengthy and difficult

calculation is required, little of this work had been done until quite

recently when techniques and computers have become available and

the exigencies of the IGY and satellite programs have made it imperative.

In the course of its development of facilities for electron den

profile calculations, the CRPL has succeeded in devising means by

which basic data for this purpose may be scaled by the individual field

stations, thereby decentralizing and simplifying the most onerous part

of the work. Through its own station network and those of the U. S.
2

Army Signal Radio Propagation Agency, and through cooperation with

closely associated stations in other countries, the CRPL has initiated

an extensive systematic data reduction program, from which hourly

electron density profiles are being computed for the following stations:

Puerto Rico (NBS, January 1959)

Grand Bahama Island (U. S. Army Signal Corps, February 1959)

Fort Monmouth, New Jersey (U.S. Army Signal Corps, Feb. 1959)

White Sands, New Mexico (U.S. Army SignalCorps, March 1959)

St. Johns, Newfoundland (Def. Res. Tel. Establ. Canada, June 1959)

Adak, Alaska (U.S. Army SignalCorps, June 1959)

Okinawa, Ryukus (U.S. Army Signal Corps, June 1959)

Thule, Greenland (U.S. Army Signal Corps, July 1959)

Huancayo, Peru (January I9 60)

Talara, Peru (January I960)

Baguio, Philippines (February I9 60)

Affiliation and approximate date of initial participation in this program

are given in parentheses.

The hourly electron density profiles are extensively used in the

research programs of CRPL and are supplied directly to certain other

agencies as part of various research and practical activities. However,

in this comparatively early stage, broad dissemination of the computed

data is a somewhat difficult problem.

In an attempt to make at least a summary of the results of the

program widely and rapidly available, the CRPL has initiated the

present series of reports. These provide graphical representations of

the monthly mean quiet hourly electron densities from certain of the

stations in the preceding list, from which a fairly clear picture of the

local ionosphere morphology may be obtained.

These reports contain N(h) data for the stations at Newfoundland,

Fort Monmouth, Grand Bahama Island, White Sands, and Puerto Ric<

Pertinent facts concerning these stations are given in the following

table:

:o
Table 1

Geomag. Coordinates Geog. Coordin,

fH Lat. Dip

St. Johns, Newf. 1.38Mc/s 58. 5°N 7Z°N 47°33'N 52°40'W

Ft. Monmouth, N.J. 1.46 51.7°N 71.5°N 40°15'N 74°01'W

White Sands, N.M. 1.30 41.2°N 60°N 32°24'N 106°52'W

Grand Bahama Island 1.30 37.9°N 59.5°N 26°40'N 78°22'W

Puerto Rico 1.15 30°N 51.5°N 18°30 , N 67°12'W

II. Description of Basic Data

True heights of reflection of radio waves are calculated from the

observed or "virtual" heights by the method of Budden (1954); this

method need not be described here, but it should br pointed out that

full correction for geomagnetic field effects is made and that the

usual restrictions to monotonic profiles apply.

Tabulations of the mean electron density data at 10 km intervals

and certain related quantities are the bases for the graphs and charts,

A sample for the Puerto Rico October data is given on Page 1 1 .

The table on the following page identifies the quantities appearing on

the tabulation.
4

Quantity Units Remarks

Average Electron Density (N)

3 3 xlO = electron/cm

_5

(10 on maps)

Body of table; given at each

10 km of height from the

lowest hmin to 950 km.

NMAX xlO-5 - electron/cm

(10~5 on maps) The mean value of Nmax.

COUNT Count of the number of

profiles entering the mean.

HMIN Kilometers The average height of zero

or very low electron density,

obtained by linear extrapolation of the electron density

of the individual profiles.

HMAX Kilometers The average height of maximum electron density, determined by fitting a parabola

to the upper portion of the

individual profiles.

SCAT Kilometers One half of the half -thick - ness of the parabola best

fitting the upper portion of

the F-region profile. Approximates the scale height

near the true HMAX.

SHMAX xlO = electrons/

cm column

-12

(10 on maps)

Obtained by averaging the

integration of the individual

profiles between the limits

HMIN and HMAX.

SHINF xlO = electrons/

cm column

13

( 10 on maps)

The average total number

of electrons in a column to

infinity obtained by extrapolation of observed profiles

into the region above HMAX.

(See text. )
5

The following particular features of the tabulated data should be

noted:

A. Averaging process . Each hour of each day is identified with

its magnetic character figure, Kp. For each hour, those days for

which Kp is less than 4+ are included in the "quiet" average. The

other days are similarly combined to form a "disturbed" average;

however, this rarely has physical significance because the number of

disturbed periods is usually small and the behavior of the ionosphere

during disturbed hours is not consistent. Thus, graphs for these

latter averages are not presented here.

B. Determination of hmax. The nature of the "true height"

process is such that no direct measure of hmax F2 is obtained, the

virtual height at Nmax being immeasurable. A useful procedure is

to fit the portion near hmaxF2 with a suitable curve and to determine

hmax from this curve. A parabola is quite satisfactory for this purpose; it is fitted to two of the highest true heights and the measured

value of Nmax(foF2).

C. Extrapolation of profiles above hmax. Before averaging, the

individual profiles are extrapolated above hmax by a Chapman distribution of 100 km scale height. This assumed model seems to agree

well with the few published measurements dealing with the profile of

the F region above hmax (Wright, I960). Extrapolation is necessary

in order to calculate homogeneous averages near hmax, and the average

profiles are, in fact, given to 950 km.

D. Integrated electron densities . The total number of electrons

in a unit column of the ionosphere between the effective bottom (hmin)

and hmax is called Shmax; it is obtained by numerical integration of

the observed profiles between these limits. An estimate of the total

electron content to infinity, based upon the Chapman model, is called

Shinf. It is obtained by adding to Shmax the quantity N^ = 2. :s^ HNmax

where H is an (assumed constant) scale height for the region above

hmax. Current evidence (Wright, I960) indicates H - 100 1 an acceptable choice.
III. Description of Graphical Representation

The relative smoothness of mean quiet ionosphere data lends

itself to various kinds of graphical presentation which offer convenient aids to the visualization of the height, geographic, and temporal variability of the ionosphere. Included here are three such

graphical forms prepared from the tabulations described in Section II.

A. Vertical cross sections of the ionosphere along the 75 W

meridian. Pages 12 through 35 give, for each hour, a vertical cross

section of the mean quiet ionosphere along a meridian section,

nominally the 75 W geographic meridian, for the month of October

1959« Contours are parametric in "plasma" frequency (f]\f) related to

electron density N by

2 / 3 12,400 fN

(Mc/s) = N(electrons/cm ). The height of maximum electron density is represented by a dashed

line. Note that the vertical scale is expanded about 5.5 times.

With the exception of White Sands, each of these stations is

reasonably close to the 75 W meridian (see Table 1). There is the

possibility that some of the anomalies imposed by White Sands on

these contours are the result of the well-known longitudinal asymmetry

of the ionosphere.

B. Local time vs. Latitude Maps . Another form of presentation,

useful for indicating the two-dimensional geographic variations of the

ionosphere, is that illustrated by the maps of pages 36 through 45.

Here, for fixed levels in the ionosphere (150, 200, 250, 300, 350,

400 km), contours of electron density are drawn in the latitude vs.

local time plane. To the extent to which longitude anomalies are

negligible, these maps give also the longitude vs. latitude distribution

of electron densities at the indicated heights when it is noon over the

75 W meridian. Similar maps for the peak density, Nmax; its height,

hmax; its characteristic thickness, Scat; the total electron content to

Nmax, Shmax; and the estimated total electron content, Shinf, are also

shown.
C. Electron density vs. time curves (N(t) curves) . The mean

quiet diurnal variation of electron density between 150 and 400 km

heights above the sounding stations is illustrated by these curves.

Dashed lines are used wherever the electron density at any height

falls below the peak density (i.e. when the height hmaxF2 falls below

the height for the curve in question.) Such electron densities are the

result of the extrapolations by the Chapman model discussed in

Section II C.

IV. Discussion and Applications of the Data

Mean quiet electron density data over wide geographic areas are

essential for application to numerous problems of both practical and

scientific interest. For example, the assessment of the radio refraction errors and Faraday rotation effects in satellite tracking requires

a knowledge of the electron density profile in the direction of the satellite or an estimate of the electron density at the satellite itself.

Alternatively these properties of the ionosphere, or estimates of the

total electron content in a column, may be measured by observations

from rockets and satellites, or from radar moon-echoes, and compared with ground-based observations of the kind shown here.

Frequently it will be necessary to use instantaneous density data

because of the considerable variability of the ionosphere about the

quiet mean. In such cases, the mean data are of value as a "refVrence

level" in the design of the experiment; for example, in the choice of

radio frequencies, satellite heights, antennas, etc.

Since electron density data represent virtually our only source of

continuous, widespread data on the earth's upper atmosphere, such

data also are essential to geophysical problems involving the electrical,

neutral, and magnetic properties of the atmosphere.
8

For example , data on the vertical cross sections may be compared

with theoretical expectations for the meridional height dependence of

the quiet ionosphere. Several workers (Hirono, 1955; Martyn 1956)

have investigated the equilibrium height (of hmax) for an ionosphere

controlled by diffusion, height-varying electron loss rate, and uniform

(or zero) vertical electron drift. The results are qualitatively in agreement with these observations in predicting a rise of hmax towards the

equator in daytime and a reversal of this tendency at night.

The N(t) curves are perhaps the most physically significant representation of electron density data. The strong solar control at all levels

and the important perturbations of this solar control in the upper F

region may be easily seen.
Acknowledgments

We are indebted to Mr. A. H. Shapley for guidance in the

initiation of this work, and to Dr. H. H. Howe for the development of the computer programs upon which the whole system

heavily depends. This series of reports results from the com

bined efforts of the NBS Electron Density Profile Group,

including at various times L. R. Wescott, L. Hayden, D. J. Brown, F. J. Burmont, I. Ford, N. Moore, M. Durham,

G. Lira, under the direct supervision of G. H. Stonehocker.

The cooperation of the U. S. Army Signal Radio Propagation

Agency is gratefully acknowledged.
10

References

Budden, K. G. , "A method for determining the variation of

electron density with height (N(z) curves)

from curves of equivalent height against frequency (h'(f) curves). Proc. Cambridge Conf.

on the Physics of the Ionosphere, pp 332-339,

September 1954, Pub. by the Physical Society

(1955).

Martyn, D. F. , "Processes controlling ionization distribution

in the ionosphere," Aust. J. Phys. 9_, pp 161-

165, March 1956.

Hirono, M. ,

Smith, N. ,

Wright, J. W.

"Effect of gravity and pressure gradient on

vertical drift in the F2 region," Rpt. on Iono.

Res. in Japan, 9, No. 2, pp 95-104, (1955).

"The relation of Radio Skywave Transmission

to Ionosphere Measurements," Proc. IRE, 27,

No. 5, pp 332-347, (1939).

"A model of the F region above hmaxF2,"

Journal of Geophysical Research, 65, pp

185-191, January I960.
11

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m • • • • ^~ ? X p-> -4 X 45 r- X ON O rg * / 43 r- ao a O O C gr ' (

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•
12

OCTOBER 1959

OOOO 75° W TIME

800

700

600

en 500

DCUl

h-LU

* 400

z

K-X

CD

UJX 300

200

100

CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 5.5 X HORIZONTAL SCALE

NEWFOUNDLAND

I FORT MONMOUTH

I

WHITE SANDS GRAND BAHAMA

_L I PUERTO RICO

_i I 50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20e
13

OCTOBER 1959

OIOO 75° W TIME

800

700

600

c/> 500

<r

UJF

UJ3

z

t-I

UJI 300

4O0

200

100 CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I I

VERTICAL SCALE 55 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

_L _L 1- 50° 45" 40° 35° 30° 2 5" NORTH GEOGRAPHIC LATITUDE

20° 15'
14

OCTOBER 1959

0200 75° W TIME

800

700 —

600 —

en 500

tr

LU

\-

LUS

Q_l^ 400

Z

H

XO

UlX 300

200

100

/

CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 5.5 X HORIZONTAL SCALE

NEWFOUNDLAND FORT MONMOUTH

L_j I

WHITE SANDS GRAND BAHAMA

i_

PUERTO RICO

_L 50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20c 15
15

800

OCTOBER 1959

0300 75° W TIME

700

600

U) 500

IEb

2

I

* 400

X

UJI 300

3

200

100 —

CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I I

VERTICAL SCALE 55 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA

I I I .

PUERTO RICO

50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20° I5«
16

800

OCTOBER 1959

0400 75° W TIME

700

600

co 500

tr

ill h-UJ3

* 400

CD

LUX 300

200

100

CONTOURS OF fN

h~ MAXIMUM

VERTICAL SCALE 5.5 X HORIZONTAL SCALE

NEWFOUNDLAND

I L_

FORT MONMOUTH WHITE SANDS GRAND BAHAMA

J I I I I

PUERTO RICO

_i I 50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20° 15
17

OCTOBER 1959

0500 75° W TIME

800

700

600

(/> 500

400

I 300

200

100 —

CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I

I

VERTICAL SCALE 55 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

J_ J_ 50° 45° 40° 35° 30° 2 5" NORTH GEOGRAPHIC LATITUDE

20° I5«
800

18

OCTOBER 1959

0600 75° W TIME

700

600

co 500

ceuj

\-LU3

* 400

X

CD 300

200

100 CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I .

I

VERTICAL SCALE 5.5 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA

J I I .

PUERTO RICO

_. I 50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20e 15'
800

19

OCTOBER 1959

0700 75° W TIME

700

600

CO 500

UJ

3

* 400

I

UJI 300

200

100

CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND

I I

FORT MONMOUTH

I

VERTICAL SCALE 55 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

1 J_ j_

50° 45° 40° 35° 30° 2 5° NORTH GEOGRAPHIC LATITUDE20°
800

20

OCTOBER 1959

0800 75° W TIME

40° 35° 30° 25c NORTH GEOGRAPHIC LATITUDE
21

OCTOBER 1959

0900 75° W TIME

2 —

CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 55 X HORIZONTAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I I I

WHITE SANDS GRAND BAHAMA

I 1 PUERTO RICO

J I 50° 45° 40° 35° 30° 2 5° NORTH GEOGRAPHIC LATITUDE

20° I5«
22

OCTOBER 1959

OOO 75° W TIME

800

700

600

en 500

LU3

*: 400

X

LUX 300

200

100

CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 5.5 X HORIZONTAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I I

I WHITE SANDS GRAND BAHAMA

j L 1 I i

PUERTO RICO

_l I 50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20° «
23

OCTOBER 1959

00 75° W TIME

800

700

600

en 500

trUJ

^-IUS

3

¥ 400

X

o

UJI 300

200

100 CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 55 X HORIZONTAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I I I WHITE SANDS GRAND BAHAMA

I I PUERTO RICO

50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20°
24

OCTOBER 1959

1200 75° W TIME

800

700

600

cn 500

orUJ

h-3

* 400

I-X

UJX 300

200

100

---—''

CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 5.5 X HORIZONTAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I I I

WHITE SANDS GRAND BAHAMA

J I I I I

PUERTO RICO

_i I 50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20c

\t
25

OCTOBER 1959

1300 75° W TIME

800

700

600

(/) 500

9

* 400

X

o

UJX 300

200 —

100 —

CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 55 X HORIZONTAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I i L_

WHITE SANDS GRAND BAHAMA

I I

I I

PUERTO RICO

50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20c I5«
26

800

OCTOBER 1959

1400 75° W TIME

700 —

600

en 500

ce

I-UJ3

^ 400

X

UJX 300

200

100 — - 2

CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I I

VERTICAL SCALE 5.5 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

_j_l

50c 45c 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20c 15'
800

27

OCTOBER 1959

1500 75° W TIME

700

600

o> 500

(TUJ

h-Ui9

* 400

I

—

UlX 300

200 —

100 —

CONTOURS OF fN h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I I

VERTICAL SCALE 55 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

_L _1_ L

50° 45c 40° 35° 30° 2 5° NORTH GEOGRAPHIC LATITUDE

20' 15"
OCTOBER 1959

1600 75° W TIME

800

700

600

en 500

hi3

* 400

2

X

LUX 300

200

100

CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 5.5 X HORIZONTAL SCALE

NEWFOUNDLAND FORT MONMOUTH

I I I WHITE SANDS GRAND BAHAMA

J I

I PUERTO RICO

_l I 50° 45° 40° 35c 30< 25° 20c I5 C NORTH GEOGRAPHIC LATITUDE
29

800

700

600

c/> 500

* 400

z

h-X

o

UJX 300

200 —

100

OCTOBER 1959

1700 75° W TIME

CONTOURS OF fN

h-MAXIMUM VERTICAL SCALE 55 X HORIZONTAL SCALE

NEWFOUNDLAND

I I

FORT MONMOUTH

I

WHITE SANDS GRAND BAHAMA

I | I

PUERTO RICO _ I 50° 45° 40° 35° 30° 2 5° NORTH GEOGRAPHIC LATITUDE

20« 15'
30

OCTOBER 1959

800 75° W TIME

800

CONTOURS OF f

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I . I

VERTICAL SCALE 5.5 X HORIZONTAL SCALE

PUERTO RICO

50c

WHITE SANDS GRAND BAHAMA

-« 1 I 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20° 15
31

800

OCTOBER 1959

1900 75° W TIME

700

600

c/> 500

UJ

3

* 400

X

o

UJX 300

200 —

100 —

-N CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I I

VERTICAL SCALE 5.5 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA

J I . I

PUERTO RICO

_j_l

50e 45c 40° 35c 30" 25° 20c

NORTH GEOGRAPHIC LATITUDE
32

OCTOBER 1959

2000 75° W TIME

800

700

600

V) 500

CCUl

I-LU3

^ 400

\-

X

CD

UJX 300

200

100 CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I I

VERTICAL SCALE 5.5 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

I

I

I I I 50° 45° 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20c
33

OCTOBER 1959

2IOO 75° W TIME

800

700 -

600

co 500

UJ

Ixl z

o

2

X

400

X 300

200 —

100 —

CONTOURS OF fN h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I

I

VERTICAL SCALE 55 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

I I I I 50° 45" 40° 35° 30° 2 5° NORTH GEOGRAPHIC LATITUDE

20c
34

800

OCTOBER 1959

2200 75° W TIME

700

600

</) 500

CEUl

h-LUg

* 400

X

UlX 300

200

100 CONTOURS OF fN

h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I I

VERTICAL SCALE 5.5 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

_i_ _L J_ _i_ 50° 45c 40° 35° 30° 25°

NORTH GEOGRAPHIC LATITUDE

20c
35

OCTOBER 1959

2300 75° W TIME

800

700 -

600

in 500

a:

UJo

400

I

19UJI 300

200

100 —

CONTOURS OF fN h-MAXIMUM

NEWFOUNDLAND FORT MONMOUTH

I I I

VERTICAL SCALE 55 X HORIZONTAL SCALE

WHITE SANDS GRAND BAHAMA PUERTO RICO

I I

I I I 50° 45° 40° 35° 30° 2 5° NORTH GEOGRAPHIC LATITUDE

20«
36

ELECTRON DENSITY AT 150 KILDMETERS

OCTOBER 1959

TIME

00

tONTOURS-r^k X I0"S
37

ELECTRON DENSITY AT 200 KILOMETERS

OCTOBER 1959

i—

r

75° W TIME

CONTOURS' r*k X I0"

5

C mJ
ELECTRON DENSITY AT 250 KILOMETERS

OCTOBER 1959

GBI

CONTOURS --^k X I0~9
39

ELECTRON DENSiTY AT 300 KILOMETERS

OCTOBER 1959

75° W TIME

8 00

CONTOURS' -A X I0"

9 cm*
40

ELECTRON DENSITY AT 350 KILOMETERS

OCTOBER i959

CONTOURS- z^k X 10 '
41

ELECTRON DENSITY AT 400 KILOMETERS

OCTOBER 1959

75° W TIME I , ,ft-5 CONTOURS' -*k X 10

C rTW
GBI

42

MAXIMUM ELECTRON DENSITY

NMAX

OCTOBER 1959

75° W TIME

CONTOURS^— x IO~ 5 cm-
43

HEIGHT OF MAXIMUM ELECTRON DENSITY

HMAX

OCTOBER 1959

N° 50

75° W TIME
44

QUARTER THICKNESS OF F-REGION PEAK

SCAT

OCTOBER 1959

6BI75° W TIME

8 OOl

CONTOURS = Km
45

ELECTRON DENSITY INTEGRATED TO HEIGHT

OF MAXIMUM ELECTRON DENSITY

SHMAX

OCTOBER 1959

75° W TIME

CONTOURS = ^-t col * lO"'* cm*
46

ELECTRON DENSITY INTEGRATED TO INFINITY

SHINF

OCTOBER 1959

75° W TIME

oc

CONTOURS = ^L col. x

10"'
47

25

20

EoI 15

n mO

>-

(/) Z

UJO

o

I-o

UJ

_lUJ

10

00

N(t) NEWFOUNDLAND OCTOBER 1959

—

FIXED HEIGHTS IN Km

—

If; /4oo \ \\

1 ' \ \

1 1 \ A\

/// \250 ^

#/ X \s200 \ \ \

/// / \ \ \

ft / \ \ \

/// 150 \ \ \

L-U4-4-W1 i i i i 1 i i i f\ i rsj i

5 —

12 LMT

18 00
25

20

48

N(t) FT. MONMOUTH OCTOBER 1959

FIXED HEIGHTS IN Km
25

49

N(t) WHITE SANDS OCTOBER 1959

FIXED HEIGHTS IN Km
50

25

N(t) GRAND BAHAMA OCTOBER 1959

FIXED HEIGHT IN Km

20

Eo« 15

O

CO

UJO

Z

o

q:

h-o

UJ

_1

UJ
25

51

20 —

00

N(t) PUERTO RICO OCTOBER 1959

FIXED HEIGHT IN Km

/\300 \350

r \ '•" *** \

/'/ >6 •

I / 40 °

II 1 h '

i

\\ \

v \

v \ \ \

\\\

/"/ \

/'y \

it i \

if \

h V-

/'/

/'/

\\\

\i\

\\\

1*1

M

M

1M

111

250 \\\

\i\

>. \ \\

\ \ A \ \ A III

/'/

/// M

it j

\ \ A

\ \

\ V \\

\ \ A

\ \ A

\ vvs\

200 \ V

V

N \

\\

\\

\\

\\ 150 \ \

MM 1 I II l

1 i i i Nn i i 1 1

10 —

12 LMT

18

U I 0O>l»--l« .. » ,

In

P

DEPAHTM1 COMMEH

Luther II. Hodges, Secretary

NATIONAL BUREAU OF STANDAK

A. V. Astin, Director THE NATIONAL BUREA1 01 SI 1NDARDS

a of the National Bureau of Standards at its major laborat , and

Boul I in the following listing of the division

search, development, and engineering in >d by

nption of the activities, and of the resultant publi fthr

Iron!HUM.TON, U.C.

ce and Reactance. Electrochemistry. il Instrument urementa

High Voltage.

Metrology. Photometry and Colorimetry. Refractometry. Photographic Research. Length. I ng Metrology.

le. Volumetry and Densimetry.

Ileal. Temperature Physics. Heat Measurements. Cryogenic Phya .ation of State. St ^ics. Radiation Physics. X-ray. Radioactivity. Radiation Theory. High Energy Radiation. Radiol- juipment.

utation. Neutron Phys

Analytical and Inorganic Chemistry. Pure Substances. Spectrochemistry. Solution Chemistry. Standard Refer-

• rials. Applied Analytical Research, Crystal Chemistry.

Mechanics. Sound. Pressure and Vacuum. Fluid Mechanics. Engineering Mechanics. Rheology. Combustion

Contr Polymers. Macromolecules: Synthesis and Structure. Polymer Chemistry. Polymer Physics. Polymer Characn. Polymer Evaluation and Testing. Applied Polymer Standards an<l Research. Dental Reseat.

Metalluri. ig Metallurgy. Microscopy and Diffraction. Metal Reactions. Metal Phyi

Metal Deposition.

Inorganic Solids. Engineering Ceramics. Class. Solid State Chemistry. Crystal Growth. Physical Properties,

hy. Ituilding Research. Structural 1 ne. Fire Research. Mechanical Systems. 'uilding Materials. Standards. Heat Transfer. Inorganic Building Materials. Metallic Build. lajs. Applied Mathematics. Numerical Analysis. Computation. Statistical I ing. Mathematical Physli a, Opirch. Data lYocessing Systems. Components and Techniques. Computer Technology. Measurements Automation.

plications. Systems Anah

Atomic Physics. v '|>v. Infr. I ..r I

Instrumentation. Engineering Electronics. I lei iron l

hysics] Chemistry, i

. and Radiation ( bemi

Office of Weights and Measut BOULDER, COLO.

nieeriim Laboratory. Cryoc ipment. I tes. Pro

CI MR XL RADIO PROPAGATION LABORATORY

Ionosphere Research and Propagation. I ucEarth Relationships. Field

Radio Propagation I ngineering. Data Ri Instrumi

Radio Systems. Applied I High I quenc) Utilization. Modulation h. Anten

Uppei Atmosphere and space Physics. '

UNO SI \M)\KI)S I iBOH IT0R1

Radio Physics. i< Standards. H • circuit Standards. High I Imp* utioa
NBS