EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

12 7 200

q 0
\
|
Ay = 500004
0 MLT —— 250 nT 00
ELECTRIC POTENTIAL |ONOSPHERIC CURRENT

JOULE HEATING FIELD-ALIGNED CURRENT
vr 200 mT 200 :
12

TOTAL

7 Auy= 4x 1077 Asm?
1.53 x 10


be

SLEI6IYVN BZEI'SIYVW BZ2é6IZIYUVA
gh zlo9 o st z9 o gs a 9 Oo

a

LUOO0O0?

ritit

potas Pri tir tiitir

LNANOdWOO “A
NIVHO VIAVNIGNVOS

MOYO

owvsnn

aand IL LUV

OAS»

SANNTM

SWSYVHS

VAONYOPa

GNNSAW AN

YON

23


WORLD DATA CENTER A

National Academy of Sclences
2101 Constitution Avenue, NW
Washington, D.C. 20418 USA

World Data Center A consists of the Coordination Office
and the following elght Subcenters:

COORDINATION OFFICE
World Data Center A
Natlonal Academy of Sclences
2101 Constitution Avenue, NW
Washtngton, D.C. 20418 USA
(Telephone: (202) 334-3359]

GLACIOLOGY (Snow and Ice)

World Data Center A: Glaclology
(Snow and Ice)

Cooperative Inst. for Research In
Environmental Sciences

University of Colorado

Boulder, Colorado 80309 USA

(Telephone: (303) 492-5171]

MARINE GEOLOGY AND GEOPHYSICS
(Gravity, Magnetics, Bathymetry,
Seismic Profiles, Marine Sediment
and Rock Analyses):

World Data Center A for Marine
Geology and Geophysics

NOAA, D64

325 Broadway

Boulder, Colorado 80303 USA

[Telephone: (303) 497-6487]

METEOROLOGY (and Nuclear Radiation)
World Data Center A: Meteorology
Nattonal Climatic Center

Federal Building

“Asheville, North Carolina 28801 USA

(Telephone: (704) 258-2850, ext. 381]

OCEANOGRAPHY

World Data Center A: Oceanography

National Oceanic and Atmospheric
Admint stration

2001 Wisconsin Avenue, NW

Page Bldg. 1, Rm. 414

Washington, D.C. 20235 USA

(Telephone: (202) 634-7249]

ROCKETS AND SATELLITES

World Data Center A: Rockets and
Satel lItes

Goddard Space Flight Center

Code 601

Greenbelt, Maryland 20771 USA

(Telephone: (301) 344-6695]

ROTATION OF THE EARTH

World Data Center A: Rotation
of the Earth

U.S» Naval Observatory

Washington, D.C. 20390 USA

(Telephone: (202) 254-4547)

SOLAR-TERRESTRIAL PHYSICS (Solar and
Interplanetary Phenomena, Inospheric
Phenomena, Flare-Assoclated Events,
Geomagnetic Variations, Aurora,
Cosmic Rays, Alrglow):

World Data Center A

for Solar-Terrestrial Physics
NOAA, D63
325 Broadway
Boulder, Colorado 80303 USA
[Telephone: (303) 497-6323]

SOLID-EARTH GEOPHYSICS (Selsmology,
Tsunamis, Gravimetry, Earth Tides,
Recent Movements of the Earth's
Crust, Magnetic Measurements,
Paleomagnetism and Archeomagneti sm
Volcanology, Geothermics):

World Data Center A

for Solid-Earth Geophysics
NOAA, 062
325 Broadway
Boulder, Colorado 80303 USA
(Telephone: (303) 497-6521

World Data Centers conduct International exchange of geophysical observations In accordance with the
principles set forth by the International Councl] of Sclentific Unions. WDC=A Is established in the
United States under the auspices of the National Academy of Sciences. Communications regarding data
Interchange matters in general and World Data Center A as a whole should be addressed to World Data

Center A, Coordination Office (see address above).

Inquiries and communications concerning data In

specific disciplines should be addressed to the appropriate sub center listed above.



EQUIVALENT CURRENT
12

7 1100

Tr 1100

ELECTRIC

JOULE

HEATING

—= 250 nT

EQUIVALENT CURRENT SYSTEM

Tr 1100

50°

Ay = 50000A

IONOSPHERIC CURRENT

7 1100

FIELD-ALIGNED CURRENT

7 1100

Muy 4% 1077 Asm?



EQUIVALENT CURRENT

12

JOULE

HEATING

06

Au, = 5 mW/m=

EQUIVALENT CURRENT SYSTEM

Tr 2200

FIELD-ALIGNED CURRENT
vr 2200

A dye 4X 1077 Asm?


PART 2

Common-Scale Magnetograms from the 71 Stations

In Part 2, we show X_ and vn component traces for
all the 71 stations for warch 17, 18 and 19, 1978.
The scale value is marked at the right-bottom corner

of each figure.

13



EQUIVALENT CURRENT
12

EQUIVALENT CURRENT SYSTEM

Ay = 50000A

IONOSPHERIC CURRENT

FIELD-ALIGNED CURRENT

Aay= 4% 107 7Asm?





EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

12 7a 2200

Ay = 50000A

°
=
=
§
v
a
3
2,
x
8

ELECTRIC POTENTIAL IONOSPHERIC CURRENT

12

|
4%
}
|

—_
3A/m

00

FIELD-ALIGNED CURRENT

7 2200
1

Muy 4% 1077 Asm?

3.85 x 10

101


EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

O MLT —= 250 nT

POTENTIAL

Maye 4% 1077 Asm
8.65 x 10

2




EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

12 me 200

|
|
I
|
I
|
|

Ay = 500004

IONOSPHERIC CURRENT

12

A® =1okv

JOULE HEATING

a
SZ

10 — Auy = 5 mW/m?

e200
18]

TOTAL

Aue 4X 1077 Asm? |
9.21 x 10

I
f
33 |
|


EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

7 1000

12

0 MLT

Ay = 500004
—= 250 nT

ELECTRIC POTENTIAL IONOSPHERIC CURRENT

TOTAL
4.87 x 19! 20

Auy=5 mW/m*

FIELD-ALIGNED CURRENT

T1000

Yhaye 4x 1077 asm?

00

65





EQUIVALENT CURRENT
12

oO MLT —= 250 nT

ELECTRIC POTENTIAL

TOTAL
6.53 x 1020

EQUIVALENT CURRENT SYSTEM

7% 1200

50°

FIELD-ALIGNED CURRENT

78 1200

Mays 4% 1077A/m?




Tonospheric Currents and Field-Aligned Currents

Unce the electric field is determined, it is pos-
sible to derive the ionospheric current vector od from

Js Et Exn, (19)

where nis a unit radial vector. From the requirement
that thE three-dimensional current be divergence free,
the field-aligned current density j, (positive down-
wards) can be calculated as

Jy = div d= div dp (1)

Joule Heating Rate

The height-integrated Joule heating rate is defin-
ed by

uy = JE

oe (12)
= Ipe

The Joule heating rate in the entire northern hemisphere
ionosphere Uy can then be obtained by integrating uy as

Uy = Sf uy a®sine doda (13)

IV. MAGNETIC ACTIVITY ON MARCH 17-19, 1978

Figure 3 shows the combined X_ component traces
from ali the 71 stations for MarchTMl7, 18 and 19, 1978.
The upper and lower envelopes provide the AU and AL
indices, respectively, and the distance between the two
envelopes gives the AE index. Note that, from this de-
finition, these activity indices are supposed to regist-
er the peak current density, rather than an integrated
total electrojet current.

During the three-day interval, there occurred a
number of intense substorms which are identified by en-
hancements in the auroral electrojet activity. The suc-
cessive substorms at auroral latitudes have divergent
characteristics ranging from an isolated substorm to
continuous substorm activity, and from small substorms
to large substorms.

V. EXAMPLES OF THE OUTPUTS
In Figures 4a-j, we show some of the outputs from
the extensive calculation for, as an example, 1200 UT on

March 19, 1978, which is the maximum epoch of an intense
substorm.

aT COMBINED Xm COMPONENT

500

500

1000

1500

ow 2 4 6 8 wo

zi 16 eo SCS

(MARCH 17, 1979

our 2 4 6 8 i 2 a ie
MARCH 18, 1978

a a a) 8 Ra OCS
MARCH 19, 1978

Fig. 3
March 17, 18 and 19, 1978, TI
the AU (71

6

The combined Xm component from 71 high-latitude stations for

he upper and lower envelopes give

) and AL (71) indices, respectively.



TABLE OF CONTENTS

Page

PART 1
I. INTRODUCTION. 2. 1 2 ee ew ee wwe we ww ewe eee eee eee eee 1
II. OUTLINE OF THE PROJECT . 2 2 ee ee eo we ee we we we we ee we eee eee e 2
III. METHOD . 2 2 ee ww ew ee ew we te we ee we we ee ee ee eee ee 38
Current Function . 2.26 eee eee ee ee eee eee eee eee eee 4

Ionospheric Conductivity . 2. 2 ee ee ee eee ee ee eee ee eee 5

Electric Potential . 2. 2 2 ee eee ee eee eee eee eens

Ionospheric Currents and Field-Aligned Currents. . . +. 22 eee eeeee 6
Joule Heating Rate . 2 2 ee we ew ee ew ew we we we we we we eee ee 6
IV. MAGNETIC ACTIVITY ON MARCH 17-19, 1978. 2 2 ee ee eee eee eee ee 6
V. EXAMPLES OF THE OUTPUTS. . 2. 2 0 ewe ee ee eee ee eee eee ee 6

VI. AVAILABILITY OF DETAILED DATA PRODUCTS . 2 2 2 2 ee ee ee ee we we eo ew © 10
Acknowledgments. 2 2 6 2 eee ee ee ee ee eee eee eee ene
APPENDIX A: IMS Meridian Chain Workshop... 2.22. e eee eee ee ee Ll
APPENDIX B: The Data Utilization Workshop Concept .... ++ ee eeee Il

References . 2. ee ee ee ee ee ee eee eee ee ee eee ew

PART 2

Common-Scale Magnetograms from the 71 Stations... +. + 6+ ee 6 + 6 13-29

PART 3
The Hourly Plots of Observed Magnetic Perturbation Vectors,

Equivalent Ionospheric Current Systems, Estimated Ionospheric Vectors,
Joule Heating Rates, and Field-Aligned Currents. .. 6 2+ «+++ 31-102

iii






EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM
12 78 100

OMT —= 250 nT

5
ELECTRIC POTENTIAL |

3A/m

JOULE HEATING FIELD-ALIGNED CURRENT

TOTAL
1.09 x 1022 30

Auy=5 mW/m?
80

Auy= 4X 1077 Asm?


WORLD DATA CENTER A
for
Solar-Terrestrial Physics

Report UAG - 87

CHANGES IN THE GLOBAL ELECTRIC FIELDS
AND CURRENTS FOR MARCH 17-19, 1978
FROM SIX IMS MERIDIAN CHAINS
OF MAGNETOMETERS

ry

BZ
ZS

November 1982



UAG=56.

UAG-57

UAG-58

UAG-59.

UAG-60

UAG~61

UAG-62

UAG-63

UAG-64

UAG-65

UAG~66

UAG~67

UAG-68

UAG-69

UAG-70

UAG-71

UAG-72

UAG-73

UAG-74

"\so-intensity Contours of Ground Magnetic H Perturbations for the December 16-18, 1971,
Geomagnetic Storm," Y+ Kamide, Cooperative Institute for Research in Environmental Sciences,
University of Colorado, Boulder, CO, April 1976, 37 pp, $1-39-

"Manual on lonospheric Absorption Measurements," edited by Ks Rawer, Institut fur Physikalische
Weltraumforschung, Freiburg, GFR, June 1976, 302 pp, $4427.

"ATS6 Radio Beacon Electron Content Measurements at Boulder, July 1974 - May 1975," by ReB. Fritz,
NOAA Space Environment Laboratory, Boulder, CO, September 1976, 61 pp, $1.04.

"Auroral Electrojet Magnetic Activity Indices AE(11) for 1974," by Joe Haskell Allen, Carl C.
Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO,
December 1976, 144 pp, $2+16.

"Geomagnetic Data for January 1976 (AE(7) Indices and Stacked Magnetograms)," by Joe Haske! |
Allen, Car! C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data
Center, Boulder, CO, July 1977, 57 pp, $1.07.

"Collected Data Reports for STIP Interval |! 20 March - 5 May 1976, edited by Helen E. Coffey and
John Ae McKinnon, World Data Center A for Solar=Terrestrial Physics, Boulder, CO, August 1977, 313
pp, $2.95.

"Geomagnetic Data for February 1976 (AE(7) Indices and Stacked Magnetograms) ," by Joe Haskel |
Allen, Carl C. Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data
Center, Boulder, CO, September 1977, 55 pp, $1.11.

"Geomagnetic Data for March 1976 (AE(7) Indices and Stacked Magnetograms)," by Joe Haskell Allen,
Car! C. Abston and Lesiie D- Morris, National Geophysical and Solar=Terrestrial Data Center,
Boulder, CO, September 1977, 57 pp, $1-11-

"Geomagnetic Data for April 1976 (AE(8) Indices and Stacked Magnetograms)," by Joe Haskell Allen,
Carl C. Abston and Leslie Ds Morris, National Geophysical and Solar=Terrestrial Data Center,
Boulder, CO, February 1978, 55 pp, $1.00.

"The Information Explosion and Its Consequences for Data Acquisition, Documentation, Processing,"
by GeK. Hartmann, Max-Planck-Institut fur Aeronomie, Lindau, GFR, May 1978, 36 pp, $0+75-

"synoptic Radio Maps of the Sun at 3.3 mm 1970-1973," by Earle B. Mayfield and Fred |.
Shimabukuro, Aerospace Corp-, El Segundo, CA, May 1978, 30 pp, $0.75.

"lonospheric D-Region Profile Data Base, A Collection of Computer-Accessible Experimental Profiles
of the D and Lower E Regions," by LeF. McNamara, lonospheric Prediction Service, Sydney,
Austral ta, August 1978, 30 pp, $0.88 (microfiche only)+

"A Comparative Study of Methods of Electron Density Profile Analysis," by LeF. McNamara,
lonospheric Prediction Service, Sydney, Australia, August 1978, 30 pp, $0+88 (microfiche only)«

"Selected Disturbed D-Region Electron Density Profiles. Their relation to the undisturbed D
region," by LF. McNamara, lonospheric Prediction Service, Sydney, Australia, October 1978, 50 pp,
$1.29 (microfiche only).

"Annotated Atlas of H-Alpha Synoptic Charts for Solar Cycle 20 (1964-1974) Carrington Solar
Rotations 1487-1616," by Patrick S. McIntosh, NOAA Space Environment Laboratory, Boulder, CO,
February 1979, 327 pp, $3+50+

"Magnetic Potential Plots over the Northern Hemisphere for 26-28 March 1976," A.D. Richmond, NOAA
Space Environment Laboratory, Boulder, CO; HeW. Kroehl, National Geophysical and Solar-Terrestr ial
Data Center, Boulder, CO; MeA. Henning, Lockheed Missils and Space Co., Aurora, -CO; and Y. Kamide,
Kyoto Sangyo University, Kyoto, Japan, April 1979, 118 pp, $1.50.

"Energy Release in Solar Flares, Proceedings of the Workshop on Energy Release in Flares, 26
February - 1 March 1979, Cambridge, Massachusetts, U.S.A+," edited by David M. Rust, American
Science and Engineering, Ince, Cambridge, MA, and A+ Gordon Ems|fe, Harvard=Smithsonian Center for
Astrophysics, Cambridge, MA, July 1979, 68 pp, $150 (microfiche only).

"Auroral Electrojet Magnetic Activity Indices AE(11-12) for January - June 1975," by Joe Haskell
Allen, Carl Ce Abston, JeE. Salazar and J.A. McKinnon, National Geophysical and Solar-Terrestrial
Data Center, NOAA, Boulder, CO, August 1979, 114 pp, $1.75.

"ATS-6 Radio Beacon Electron Content Measurements at Ootacamund, India, October ~ July 1976," by
$.D. Bouwer, Ks Davies, ReFs Donnelly, ReNe Grubb, J«E- Jones and J«H. Taylor, NOAA Space
Environment Laboratory, Boulder, CO, and R-G. Rastogl, MeRs Deshpande, H. Chandra and G. Sethia,
Physical Research Laboratory, Ahmedabad, India, March 1980, 58 pp, $2.50.





UAG-75

UAG-76,

UAG-77

UAG-78

UAG-79

UAG-80

UAG-81

UAG-82

UAG-83,

UAG-84

UAG-85,

UAG-86

UAG-87

"The Alaska IMS Meridian Chain: Magnetic Vartations for 9 March - 27 April 1978," by H.W. Kroeh!
and G.P. Kosinsk!, National Geophysical and Solar-Terrestrlal Data Center, Boulder, 00; S.-l
Akasofu, GeJ« Romick, C.Es Campbell and G.K. Corrick, University of Alaska, Falrbanks, AK; and
.E. Hornback and A.M. Gray, NOAA Space Environment Laboratory, Boulder, 00, June 1980, 107 pp,
$3.00.

"Auroral Electrojet Magnetic Activity Indices AE(12) for July - December 1975," by Joe Haskell
Allen, Carl Ce Abston, JeE. Salazar and JeAe McKinnon, National Geophysical and Solar-Terrestrial
Data Center, NOAA, Boulder, CO, August 1980, 116 pp, $2.50.

"Synoptic Solar Magnetic Fleld Maps for the Interval Including Carrington Rotations 1601-1680, May
5, 1973 - April 26, 1979," by J. Harvey, B. Glllesple, P+ Miedaner and C. Slaughter, Kitt Peak
National Observatory, Tucson, AZ, August 1980, 66 pp, $250.

"The Equatortal Latitude of Auroral Activity During 1972-1977," by NeRs Sheeley, Jre and ReAs
Howard, E. 0. Hulbert Center for Space Research, U.S. Naval Research Laboratory, Washington, DC
and 8.$. Dandekar, Air Force Geophysics Laboratory, Hanscom AFB, MA, October 1980, 61 pp, $3.00.

"Solar Observations During Skylab, April 1973 - February 1974, 1. Coronal X-Ray Structure, Il.
Solar Flare Activity," by JeM. Hanson, University of Michigan, Ann Arbor, Ml; and E.C. Roelof and
R.E~ Gold, The Johns Hopkins University, Laurel, MD, December 1980, 43 pp, $2-50.

"ExperImental Comprehensive Solar Flare Indices for 'Major' and Certain Lesser Flares, 1975-1979,"
compiled by Helen W. Dodson and E+ Ruth Hedeman, The Johns Hopkins University, Laurel, MD, July
1981, 33 pp, $2.00.

"Evolutionary Charts of Solar Activity (Calclum Plages) as Functions of Hellographic Long!tude and
Time, 1964-1979," by Es Ruth Hedeman, Helen W. Dodson and Edmond C. Roelof, The Johns Hopkins
University, Laurel, MD 20707, August 1981, 103 pp, $4.00.

"International Reference lonosphere - IRI 79," edited by J» Virginia Lincoln and Raymond 0.
Conkright, National Geophysical and Solar-Terrestrial Data Center, NOAA, Boulder, CO, November
1981, 243 pp, $4.50.

"Solar-Geophysical Activity Reports for September 7-24, 1977 and November 22, 1977," Parts 1 and
2, compiled by John A. McKinnon and J. Virginla Lincoln, World Data Center A for Solar~Terrestr ial
Physics, NOAA, Boulder, CO, February 1982, 553 pp, $10.00.

"Catalog of Auroral Radio Absorption During 1976-1979 at Abisko, Sweden," by J«K. Hargreaves, C-M.
Taylor and J.M. Penman, Environmental Sctences Department, University of Lancaster, Lancaster, UK,
July 1982, 69 pp, $3.00.

"Catalog of lonosphere Vertical Soundings Data," edited by Raymond 0. Conkright and H. Irene
Brophy, Natlonal Geophysical Data Center, NOAA, Boulder, CO, July 1982, 107 pp, $3+50.

"International Catalog of Geomagnetic Data," compiled by J«Hs Allen and C.C. Abston, National
Geophysical Data Center, NOAA, Boulder, CO} E«P. Kharin and NE. Papitashvili, Academy of Sclences
of the USSR, World Data Center B2, Moscow, USSR; and V.0. PapItashviI1, IZMIRAN, Moscow Region,
USSR, November 1982, 188 pp, $4.00.

"Changes In the Global Electric Flelds and Currents for March 17-19, 1978, from SIx IMS Meridian
Chatns of Magnetometers," by Y. Kamide, Kyoto Sangyo UnIversity, Kyoto, Japan; H.W. Kroehl, National
Geophysical Data Center, NOAA, Boulder, CO; and A-D. Richmond, NOAA Space Envinronment Laboratory,
Boulder, CO, November 1982, 102 pp, $3-50.



LU 0002

826l ‘6l UV
mz 8 al

}

8Z6l ‘8 YVAN
al zl

ie)

B26] ZI UVM

gl él i) e)

re

rr

re

po tritisrtuinr

LNSNOdWOO “x

SAINOLVAYASEO OILANSVW YSHLO

VMVLLO

YSAIW SIVHM Lvau9

VINOLOIA
VHLIS

MOXUYVE

N3TTAM SdV9
ASLAMVA

Ava SIXtL

28




EQUIVALENT CURRENT
12

0 MLT —+ 250 nT

ELECTRIC POTENTIAL

12

3A/m

FIELD-ALIGNED CURRENT

7 00

Ady= 4% 107 7A/m?



FIELD-ALIGNED CURRENTS

MARCH 19, 1978
1200 UT

JOULE HEAT RATE

1200 UT 1

“1 pownWaRo:

CONTOUR INTERVAL
4-407 alm?

00 MLT

Fig. 41 Field-aligned current distribution.

VI. AVAILABILITY OF DETAILED DATA PRODUCTS

The complete data set is available in a form of a
16mm cine color film, which consists of four segments:
(1) equivalent current system, (2) electric potential
contours and ionospheric currents, (3) field-aligned
currents, and (4) contours of Joule heating rate. Each
frame of the film is repedted five times, allowing the
viewer to follow the progression of changes in these
quantities. This creates a movie which lasts 13 min-
utes. Film copies may be obtained from NOAA National
Geophysical Data Center, Boulder, Colorado, 80303 USA
at a cost of $150 per film. Magnetic tape copies con-
taining the 5-min original magnetometer data from the
7) stations are also available from World Data Center A
for Solar-Terrestrial Physics at the same address for a
cost of $110.

Acknowledgments

The present work would have been impossible with-
out the help of numerous persons and institutions in
obtaining the original magnetometer data. We wish to
thank Rick Guritz of the University of Alaska for his
skillful computer work in handling the large amount of
data. It would also have been impossible without the

10

2
MARCH 19, 1978 lw
ow 50S
~ cor
_— 70°
[~ aoe
\ q
06 18 ah

pe
2

iy

CONTOUR INTERVAL
0.005 W/m?

1.98E+11 W

00 MLT

Fig. 4j Joule heating rate and total Joule heat rate

integrated over the northern hemisphere.

financial support of funding agencies in many different
countries: We would like to thank the National Science
Foundation which supported both the operation of the
Alaska meridian chain and the major part of the data
analysis reported in this paper (ATM-81-08994). Y. K.
was Supported in part by the Ministry of Education,
Science and Culture of Japan under a Grant-in-Aid for
Scientific Research Project #00554105. The research
reported in this paper was accomplished while Y. K.
held a Senior Resident Research Associateship of U.S.
National Research Council at NOAA Space Environment
Laboratory. W. B. and H. M. wish to thank the Deutsche
Forschungsgemeinschaft for financial support . G. R.
acknowledges support from the Natural Sciences and
Engineering Research Council of Canada.

The workshop exemplifies the leadership, direction
and foresightedness of the previous Director of NGDC,
Alan H. Shapley. Larry D. Schultz was the leader tasked
with carrying forward the concept, establishing the
hardware and software requirements and providing soft-
ware support. Bonnie A. Hausman provided outstanding
Programming support in developing all the new products
Prepared before, during and after the workshop. Essen-
tial programming assistance was provided by Peter
Wilcoxen, Peter Sloss, and Maurine Hobbs. The typing
headaches fell upon Carol Weathers as four drafts of
the joint paper were prepared during the workshop.
Additional support was provided by Kathy Joniak, Terri
Fryar, Ron Buhmann, Joe Salazar, Carl Abstron, John
Kinsfather, and Chuck Shanks. Essential managerial
support, and useful comments on this paper were provid-
ed by Joe H. Allen, Director of WDC-A for STP.



EQUIVALENT CURRENT

7% 2100

7% 2100

ELECTRIC

O MLT —= 250 nT

POTENTIAL

1.67 x 10

11

EQUIVALENT CURRENT SYSTEM

7% 2100

lONOSPHER

7% 2100

1

Ay = 50000A

(IC CURRENT

2

FIELD-ALIGNED CURRENT

me 2100

Mgy= 4% 107 7Asm?

ee



EQUIVALENT CURRENT
12

ELECTRIC POTENTIAL

O MLT —= 250 nT

JOULE HEATING

TOTAL

9.17 x 1010 00

Au, = 5 mW/m2

EQUIVALENT CURRENT SYSTEM

I|ONOSPHER

7% 1800

if

78 1800
4

94



EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

12 ‘77 1600

MLT —= 250 nT

en oT POTENTIAL

EN
&

A® = 1okv

a

Auy=5 mW/m2

u Age 4X 1077 Asm?
1.70 x 10 co 23




EQUIVALENT CURRENT

O MLT —= 250 nT

ELECTRIC POTENTIAL

EQUIVALENT CURRENT SYSTEM

7% 1800

Ay = 500004

00

IONOSPHERIC CURRENT

7% 1800

FIELD-ALIGNED CURRENT

2



EQUIVALENT CURRENT j EQUIVALENT CURRENT SYSTEM
12

Ay = 50000A

IC CURRENT

78 2000

Aue 4% 1077 A/m?


EQUIVALENT CURRENT SYSTEM

ee

Ay = 50000A

IONOSPHERIC CURRENT
78 1000

TOTAL . -
2 Kane 4X 10° 7A/m?

1.64 x 10 47 ia









WORLD DATA CENTER A
for
Solar-Terrestrial Physics

Report UAG - 87

CHANGES IN THE GLOBAL ELECTRIC FIELDS
AND CURRENTS FOR MARCH 17-19, 1978
FROM SIX IMS MERIDIAN CHAINS
OF MAGNETOMETERS

by

Y. Kamide, H.W. Kroehl, A.D. Richmond, B.-H. Ahn, S.-l. Akasofu,
W. Baumjohann, E. Friis-Christensen, S$. Matsushita, H. Maurer,

G. Rostoker, R.W. Spiro, J.K. Walker and AN. Zaitzev

November 1982 In

U.S. DEPARTMENT OF COMMERCE
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
ENVIRONMENTAL DATA AND INFORMATION SERVICE
Boulder, Colorado, USA 80303


UAG=21

UAG=22

UAG=23

UAG=23A

UAG=24

UAG=25

UAG-26

UAG-27

UAG-28

UAG-29

UAG=30

UAG=31

UAG=32

UAG=33

UAG=34

UAG=35

UAG-36

UAG=37

"Reevaluation of Solar Flares 1967," by Helen W. Dodson and E. Ruth Hedeman, McMath-Hul bert
Observatory, University of Michigan, Pontiac, MI, and Marta Rovira de Miceli, San Miguel
Observatory, Argentina, June 1972, 15 pp, $0.15.

"Preliminary Compilation of Data for Retrospective World Interval July 26 - August 14, 1972," by
Js Virginia Lincoln and Hope 1. Leighton, World Data Center A for Solar-Terrestrial Physics, NOAA,
Boulder, ©0, November 1972, 128 pp, $0.70.

"auroral Electrojet Magnetic Activity Indices (AE) for 1970," by Joe Haskell Allen, National
Geophysical and Solar-Terrestrial Data Center, Boulder, CO, November 1972, 146 pp, $0+75.

"U.R«Se 1s Handbook of lonogram Interpretation and Reduction," Second Edition, November 1972,
edited by WeR. Piggott, Radio and Space Research Station, Slough, UK, and K. Rawer, Arbeltsgruppe
fur Physikalische Weltraumforschung, Freiburg, GFR, November 1972, 324 pp, $1-75«

"UsReSel» Handbook of lonogram Interpretation and Reduction," Second Edition, Revision of Chapters
1-4, edited by WsR. Piggott, Radio and Space Research Station, Slough, UK, and K- Rawer,
Arbeitsgruppe fur Physikalische Weltraumforschung, Freiburg, GFR, November 1972, 135 pp, $2.14.

"Data on Solar-Geophysical Activity Associated with the Major Ground Level Cosmic Ray Events of 24
January and 1 September 1971," Parts 1 and 2, compiled by Helen E. Coffey and J+ Virginia Lincoln,
World Data Center A for Solar-Terrestrial Physics, NOAA, Boulder, CO, December 1972, 462 pp, $2+00
includes Parts 1 and 2).

"Observations of Jupiter's Sporadic Radio Emission In the Range 7.641 MHz, 9 September 1968
through 9 December 1971," by James W. Warwick, George A+ Dulk and David G. Swann, University of
Colorado, Boulder, 00, February 1973, 35 pp, $0.35.

"Data Compilation for the Magnetospher ically Quiet Periods February 19-23 and November 29 -
December 3, 1970," compiled by Helen E. Coffey and J. Virginia Lincoln, World Data Center A for
Solar-Terrestrial Physics, NOAA, Boulder, CO, May 1973, 129 pp, $0.70.

"High Speed Streams in the Solar Wind," by D.S. Intriligator, University of Southern California,
Los Angeles, CA, June 1973, 16 pp, $0+15-

"Collected Data Reports on August 1972 Solar-Terrestrial Events," Parts 1, 2 and 3, edited by
Helen E. Coffey, World Data Center A for Solar-Terrestrial Physics, NOAA, Boulder, CO, July 1973,
932 pp, $4.50.

"Auroral Electrojet Magnetic Activity Indices AE(11) for 1968," by Joe Haskell Allen, Carl Ce
Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO,
October 1973, 148 pp, $0.75.

"Catalogue of Data on Solar-Terrestrial Physics," prepared by NOAA Environmental Data Service,
Boulder, C0, October 1973, $1.50. Supersedes UAG-I1, 15, and 20 catalogs.

"Auroral Electrojet Magnetic Activity Indices AE(11) for 1969," by Joe Haskell Allen, Carl C.
Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO,
February 1974, 142 pp, $0.75.

"synoptic Radio Maps of the Sun at 3.3 mm for the Years 1967-1969," by Earle B. Mayfield, Kennon
P. White Il, and Fred |. Shimabukuro, Aerospace Corp-, El Segundo, CA, April 1974, 26 pp, $0.35.

"Auroral Electrojet Magnetic Activity Indices AE(10) for 1967," by Joe Haskel! Allen, Carl! Ce
Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO,
May 1974, 142 pp, $0.75.

"Absorption Data for the IGY/I1GC and 1QSY," compiled and edited by AeH. Shapley, National
Geophysical and Solar-Terrestrial Data Center, Boulder, CO; W.R. Piggott, Appleton Laboratory,
Slough, UK; and K. Rawer, Arbeltsgruppe fur Physikalische Weltraumforschung, Freiburg, GFR, June
1974, 381 pp, $200.

"Catalogue of Digital Geomagnetic Variation Data at World Data Center A for Solar-Terrestrial
Physics," prepared by NOAA Environmental Data Service, Boulder, CO, July 1974, 20 pp, $0+20.

"An Atlas of Extreme Ultraviolet Flashes of Solar Flares Observed via Sudden Frequency Deviations
During the ATM-SKYLAB Missions," by ReF+ Donnelly and EL. Berger, NOAA Space Environment
Laboratory; Lt. J«D. Busman, NOAA Commissioned Corps; B. Henson, NASA Marshal! Space Flight
Center; T.B. Jones, University of Leicester, UK; G.M. Lerfald, NOAA Wave Propagation Laboratory;
K. Najita, University of Hawaii; W.M. Retallack, NOAA Space Environment Laboratory and Wede
Wagner, Sacramento Peak Observatory, October 1974, 95 pp, $0.55+

"Auroral Electrojet Magnetic Activity Indices AE(10) for 1966," by Joe Haskell Allen, Car! Ce
Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO,
December 1974, 142 pp, $0+75+



EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM
12

Ay = 50000A

0 MLT —= 250 nT

ELECTRIC POTENTIAL 1ONOSPHERIC CURRENT

12

A® = 10kv

TOTAL
9.07 x 10

10 Age 4X 1077 Asm?



EQUIVALENT CURRENT

—~ 250 nT

JOULE

HEATING

A® =10kv

TOTAL

1.08 x 102!

Au, = 5 mW/m?

EQUIVALENT C

Te 1900

URRENT SYSTEM

Ay = 50000A

00

lONOSPHER’

IC CURRENT

FIELD-ALIGNED CURRENT

50

Adz 4% 1077 Asm?



EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

50° |

|

|

8 |

|

|

Ay = 50000A I

O MLT —= 250 nT

om POTENTIAL, IONOSPHERIC CURRENT

Ae lokv

JOULE HEATING ~

©

Auy= 5 mW/m?

TOTAL

Maye 4% 1077 Asm?

2.30 x 10+ 99


14 0002

826l ‘Gl UV 826 ‘8! “VA

ve Bl él i) ie) 8l dl 9 ie)

826l ZI UV
a)

0

TIT

rtisttiiti pitiirtiitir

TI TT

=TIANNSWVTM

=-1VWYSONV

*-T/SENVL

4 ASAVSVEVHY

GNVISI AA1a€

--GNV ISI NOX!

“7 NAVA

NoNWis! SSI3H

LNANOdWOd “4X
NIVHO NVUINZI

24


14 0002

be

826 ‘Gl YVAN
ee)

826l ‘81 UV
oO g 2 =9 Oo

8261 Z| YVW
ga

O

TT

TT 11-7

TT

a

ritiitiritir

a

=4 OVNSSUVSSHVN

-) @VHSMIY303u4

@VHLGOS

NAVHGOS

YVNVWN

MIAVNY dN

SINHL

INJNOdWoo “x
NIVHO GNVIN33Y9

20


UAG SERIES OF REPORTS

Fewer than four UAG Reports are published at irregular intervals each year. Copies of these publications
may be purchased through World Data Center A for Solar-Terrestrial Physics, Environmental Data and Information
Service, NOAA, D63, 325 Broadway, Boulder, Colorado 80303, USA. A $4.00 handling charge per order will be added to
the single-copy prices listed below. Please note, too, that some reports are available on microfiche only. Orders
must include check or money order payable in UeS. currency to the Department of Commerce, NOAA/NGDC.

UAG-1—""IQSY Night Airglow Data," by LeL. Smith, FeE. Roach, and J«M. McKennan, ESSA Aeronomy Laboratory,
Boulder, CO, July 1968, 305 pp, $1-75-

UAG-2 "A Reevaluation of Solar Flares, 1964-1966," by Helen W. Dodson and E. Ruth Hedeman,
McMath-Hulbert Observatory, University of Michigan, Pontiac, MI, August 1968, 28 pp, $0-30.

UAG-3 "Observations of Jupiter's Sporadic Radio Emission in the Range 7.6-41 MHz, 6 July 1966 through 8
September 1968," by James W. Warwick and George A+ Dulk, University of Colorado, Boulder, CO,
October 1968, 35 pp, $0+55.

UAG-4 "Abbreviated Calendar Record 1966-1967," by J+ Virginia Lincoln, Hope 1. Leighton and Dorothy K+
Kropp, ESSA now NOAA, Aeronomy and Space Data Center, Boulder, 00, January 1969, 170 pp, $1425.

UAG-5 "Data on Solar Event of May 23, 1967 and its Geophysical Effects," compiled by J. Virginia
Lincoln, World Data Center A, Upper Atmosphere Geophysics, ESSA now NOAA, Boulder, CO, February
1969, 120 pp, $0.65.

UAG-6 "International Geophysical Calendars 1957-1969," by AsH. Shapley and J. Virginia Lincoln, ESSA
Research Laboratories, now NOAA, Boulder, CO, March 1969, 25 pp, $0+30.

UAG-7 “Observations of the Solar Electron Corona: February 1964 - January 1968," by Richard T. Hansen,
High Altitude Observatory, NCAR, Boulder, CO, and Kamuela, HI, October 1969, 12 pp, $0+15+

UAG-8 "Data on Solar-Geophysical Activity October 24 - November 6, 1968," Parts 1 and 2, compiled by J«
Virginia Lincoln, World Data Center A, Upper Atmosphere Geophysics, ESSA now NOAA, Boulder, CO,
March 1970, 312 pp, $175 (includes Parts 1 and 2)+

UAG-9 "Data on Cosmic Ray Event of November 18, 1968 and Associated Phenomena," compiled by J+ Virginia
Lincoln, World Data Center A, Upper Atmosphere Geophysics, ESSA now NOAA, Boulder, CO, April 1970,
109 pp, $055.

UAG=10 "Atlas of lonograns," edited by AeH. Shapley, ESSA Research Laboratories now NOAA, Boulder, CO,
May 1970, 243 pp, $1.50.

UAG-12 "Solar-Geophysical Activity Associated with the Major Geomagnetic Storm of March 8, 1970," Parts
1, 2 and 3, compiled by J. Virginia Lincoln and Dale 8. Bucknam, World Data Center A, Upper
Atmosphere Geophysics, ESSA now NOAA, Boulder, CO, April 1971, 466 pp, $3.00 (includes Parts 1-3).

UAG-13 "Data on the Solar Proton Event of November 2, 1969 through the Geomagnetic Storm of November
8-10, 1969," compiled by Dale B. Bucknam and J. Virginia Lincoln, World Data Center A, Upper
Atmosphere Geophysics, ESSA now NOAA, Boulder, CO, May 1971, 76 pp, $0+90-

UAG=14 "An Experimental, Comprehensive Flare Index and Its Derivation for 'Major" Flares, 1955-1969," by
Helen W. Dodson and E. Ruth Hedeman, McMath-Hulbert Observatory, University of Michigan, Pontiac,
MI, July 1971, 25 pp, $0+30.

UAG-16 "Temporal Development of the Geophysical Distribution of Auroral Absorption for 30 Substorm Events
in each of IQSY (1964-65) and IASY (1960)," by FT. Berkey, University of Alaska, Fairbanks, AK;
V.M. Driatskiy, Arctic and Antarctic Research Institute, Leningrad, USSR; K. Henriksen, Auroral
Observatory, Tromson, Norway; D-H. Jelly, Communications Research Center, Ottawa, Canada; T.l+
Shchuka, Arctic and Antarctic Research Institute, Leningrad, USSR; A. Theander, Kiruna Geophysical
Observatory, Kiruna, Sweden; and J. Yliniemi, University of Oulu, Oulu, Finland, September 1971,
131 pp, $0+70 (microfiche only).

UAG-17 ""lonospheric Drift Velocity Measurements at Jicamarca, Peru (July 1967 - March 1970)," by Ben Bs
Balsley, NOAA Aeronomy Laboratory, Boulder, CO, and Ronald F. Woodman, Jicamarca Radar
Observatory, Instituto Geofisico del Peru, Lima, Peru, October 1971, 45 pp, $0.55 (microfiche
only)«

UAG-18 "A Study of Polar Cap and Auroral Zone Magnetic Variations," by Ke Kawasaki and S.-I. Akasofu,
University of Alaska, Fairbanks, AK, June 1972, 21 pp, $020.

ij
|
|
|

a



EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

12 7 100

aod) -
IF | Ay = 500008

O MLT —= 250 nT 00

)

IONOSPHERIC CURRENT

JOULE HEATING

TOTAL
1.36 x 1012

Auyj= 4% 1077 Asm?



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fn) |
=
: |
a) i
|
Ady= 4X 10 Tam?
ry

A® =lokVv

, +)
OTAL 90 70 —— Auy = 5 mW/m?



EQUIVALENT CURRENT
12

0 MLT —= 250 nt

ELECTRIC POTENTIAL
7 1900

fo.)
°
i)
x

e
i=
8

EQUIVALENT CURRENT SYSTEM

Tr 1900

Aw = 50000A

lONOSPHERIC CURRENT

Tr 1900
12

3A/m

FIELD-ALIGNED CURRENT

7 1900

Asy= 4X 107 7Asm?
74



LU 0002

826l ‘6l UV
wz a 29

fe)

826l ‘BI UV
a)

Oo

8261 ZI UV
al_2i__9

0

TIT

re

---NIMSNATSHO 3dVo

OMSIEV

MOSWAIN

NAVHSYYVANVG
ONV71LYVH

=<--INIGOL dVTM

YNSOAUIS1

S,NHOP 1S

ritiitiritir

Fe ae

pitit tit

INANOdWOD “4X

SAIYOLVAYSSEO SILANOSVW YSHLO

26


EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

12 7% 1900

Ay = 500004
0 MLT —= 250 nT

ELECTRIC POTENTIAL IONOSPHERIC CURRENT
7a 1900 7a 1900

3A/m

FIELD-ALIGNED CURRENT

7a 1900

TOTAL

Au, = 5 mw/m?
8.28 x 1910 4

Maye 4% 1077 Asm?
92



Figure 4a shows the distribution of the equivalent
jonospheric current vectors which are the observed mag-
netic perturbation vectors clockwise by 90°. One can
see that the nightside westward electrojet flows in a
wide local time span, from the late morning nightside
sector to the evening sector, and maximizes in the mid-
night sector. In Figures 4b and 4c, we show the distri-
bution of isointensity contours of calculated external
current function (the so-called equivalent ionospheric
current system) and of the associated equivalent current
vectors, respectively. The current vectors are plotted
at our grid points every 1° (in latitude) and 1 hour
(in local time). Comparing Figures 4a and 4c, one must
be cautious in interpreting the derived equivalent cur-
rents in regions where there is an absence of measure-
ments. In particular, the large gap in the distribu-
tion of surface magnetometers over the Arctic Ocean and
eastern Siberia can produce significant uncertainties.

Isocontours of the assumed height-integrated Peder-
sen and Hall conductivities are displayed in Figure 4d.
Note the different contour intervals used for the two
conductivities. Figure 4e shows isocontours of the el-
ectric potential calculated for the combined set of the
current function (Fig. 4b) and the conductivity model
(Fig. 4d), and Figure 4f shows the corresponding elec-
tric field computed at our grid points. The potential
pattern consists essentially of twin vortices in high
jatitudes with the highest and lowest potentials exist-
ing in the early morning and early afternoon sectors,
respectively. However, there can exist many local de-
formations. It is important to point out that in many
earlier works, the pattern of the electric potential has
been assumed to be identical to that of the equivalent
current system. By comparing Figures 4e and 4b, it is
noticeable that the potential pattern is significantly
different from the equivalent current system at and near

EQUIVALENT IONOSPHERIC CURRENT VECTORS

1200 UT
MARCH 19, 1978

auroral latitudes. Such a difference is caused simply
by the nonuniform distribution of the ionospheric con-
ductance.

Figure 4g shows the distribution of the calculated
jonospheric current vectors. One can notice by compar-
ing the equivalent and 'true' ionospheric currents, that
although the gross distributions of the two currents are
similar, there are significant differences both in the
current direction and strength. For example, the equiv-
alent currents flow nearly in the pure east-west direc-
tion, but the 'true' ionospheric currents have a consid-
erable north-south component. In Figure 4h, we compare
the Pedersen and Hall currents, separately. It is evi-
dent that the Hall currents are remarkably similar to
the equivalent currents. However, a significant differ-
ence can be found in the polar cap, indicating that the
main source of the polar cap magnetic perturbations is
field-aligned currents, at least, during substorms.

Figure 41 shows isocontours of the calculated field-
aligned currents. There is a great variability in the
field-aligned current distribution in comparison with
the statistical pattern obtained by averaging a number
of satellite measuarements.

Finally in Figure 4j, we show the distribution of
the Joule heat production rate associated with the aur-
oral electrojets. In the left-bottom corner, the total
Joule heating integrated over the entire polar ionos-
phere (from the north pole to 50° latitude) is indicat-
ed in the unit of watts.

EQUIVALENT CURRENT SYSTEM

1200 UT
MARCH 19, 1978.

06

500 nT

Fig. 4a Examples of the outputs from the calculation.

Equivalent current vectors deduced from observed

magnetic perturbations.

CONTOUR
INTERVAL
50000 A

Fig. 4b Calculated equivalent current functions.



EQUIVALENT CURRENT
12

0 MLT

ELECTRIC

—= 250 nT

POTENTIAL

12

TOTAL

3.84 x 10!° 0

“Au, = 5 mW/m=

50°

Ay = 50000A

fi
Ga x
# ve
18] _—
e =)
eI
S$
00
IONOSPHERIC CURRENT
7 2000

12

—_—_
3A/m

FIELD-ALIGNED CURRENT
Tr 2000

75

Auy= 4X 1077 Asm?

08




Fig. 1

whose data are used in the present modeling.

Map (in eccentric dipole coordinates) of the six IMS meridian
chains of magnetometer stations and of standard observatories,

For identifica-

tion of station names, see Table 1.

Magnetic pecords from a total of seventy-one sta-
tions above 50° in geomagnetic latitude are used in
this study, and those stations are listed in Table 1.
After the paper by Kamide et al. (1982) went to press,
data from Eureka, closest to the eccentric dipole pole,
became available, thus the designation of 0 for this
station. The station distribution in eccentric dipole
coordinates (Cole, 1963) is shown in Figure 1. Note
that several subauroral stations were added for better
accuracy of the determination of the auroral electrojet
location. Data used in this paper represent horizontal
magnetic perturbations relative to the average magnetic
field level on March 12, 1978, which the quietest day
jn March 1978.

III. METHOD

A summary diagram outlining steps from digitiza-
tion through final production of a motion picture film
is given in Figure 2. The practical procedures for
each time step are as follows:

(1) Digitization of the H and D (or X and Y) com-
ponents from magnetograms from each station. Approxi-
mately 25% of all the stations used digital recorders,
so that only a formating process was necessary for
these stations. However, errors are generated during
the digitization process for most of the other stations.
We have attempted to minimize this problem and consider
timing of all digital values to be within 2.5 minutes
of their actual time.

(2) Subtraction of a base line (the average level
of March 12, 1978) for each station and transformation
into geomagnetic north, X_, and geomagnetic east, Y_,
components. In this repol't, the X_ and Y_ components
refer to the northward and eastward components in ec-
centric dipole coordinates.

(3) Calculation of geomagnetic activity indices
(derived from 71 sets of X_ values). In view of the
fact that this data set is"one of the most comprehen-
sive assembled to date from high-latitude magnetometers,
we have constructed two auroral electrojet activity
indices: AE(71) and the total westward electrojet
index F_. Substorm activity described by these indices
for theTMthree-day interval is presented in Section IV.

(4) Computation of the equivalent current func-
tion. This process involves fitting a magnetic poten-
tial function to the observed data and estimating the
portion of this potential associated with overhead
currents.

(5) Computation of the electric potential ‘in the
ionosphere at each grid point, every 1 in colatitude
and 18° (1 hr.) in longitude (local time). This pro-
cess involves the most extensive computer calculation
to solve numerically the second-order differential
equation in two dimensions. A suitable model of the
ionosphere conductivity is to be assumed.

(6) Calculation of the ionospheric current vector
at each grid point.

(7) Derivation of the field-aligned current,
which is the divergence of the ionospheric current.



EQUIVALENT CURRENT
12

ELECTRIC

Tr 2400

JOULE

TOTAL

1.23 x 10!

HEATING

2

79

EQUIVALENT CURRENT SYSTEM

Tr 2400

IONOSPHERIC CURRENT
vr 2400

Maye 4X 1077 Asm?

|
|

|
7


UAG=38

UAG-39

UAG-40

UAG=41

UAG=42

UAG=43,

UAG=44

UAG~45

UAG=46

UAG-47

UAG=48A,

UAG=49

UAG-50

UAG-51

UAG=52

UAG=53

UAG-54

UAG-55.

"Master Station List for Solar-Terrestrial Physics Data at WOC-A for Solar=Terrestrial Physics,"
by ReW. Buhmann, World Data Center A for Solar-Terrestrial Physics, Boulder, CO; Juan D. Roederer,
University of Denver, Denver, CO; and MeA- Shea and D.-F. Smart, Air Force Cambridge Research
Laboratories, Hanscom AFB, MA, December 1974, 110 pp, $1.60.

"Auroral Electrojet Magnetic Activity Indices AE(11) for 1971," by Joe Haskell Allen, Carl Ce
Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO,
February 1975, 144 pp, $2.05.

"H-Alpha Synoptic Charts of Solar Activity for the Period of Skylab Observations, May 1973 ~ March
1974," by Patrick S. McIntosh, NOAA Space Environment Laboratory, Boulder, CO, February 1975, 32
PP, $0+56.

"H-Alpha Synoptic Charts of Solar Activity During the First Year of Solar Cycle 20 October 1964 -
August 1965," by Patrick S- McIntosh, NOAA Space Environment Laboratory, Boulder, CO and Jerome T.
Nolte, Anerican Science and Engineering, Ince, Cambridge, MA, March 1975, 25 pp, $0-48.

"Observations of Jupiter's Sporadic Radio Emission in the Range 7+6-80 MHz, 10 December 1971
through 21 March 1975," by James W. Warwick, George A+ Dulk and Anthony C. Riddle, University of
Colorado, Boulder, CO, April 1975, 49 pp, $1615.

"Catalog of Observation Times of Ground-Based Skylab-Coordinated Solar Observing Programs," com=
piled by Helen E. Coffey, World Data Center A for Solar-Terrestrial Physics, NOAA, Boulder, OO,
May 1975, 159 pp, $3+00.

"Synoptic Maps of Solar 9.1 om Microwave Emission from June 1962 to August 1973," by Werner Graf
and Ronald Ne Bracewell, Stanford University, Stanford, CA, May 1975, 183 pp, $2.55.

"Auroral Electrojet Magnetic Activity Indices AE(11) for 1972," by Joe Haskell Allen, Carl C.
Abston and Leslie D. Morris, National Geophysical and Sélar-Terrestrial Data Center, Boulder, CO,
May 1975, 144 pp, $2610 (microfiche only).

"Interplanetary Magnetic Field Data 1963-1964," by Joseph H. King, National Space Science Data
Center, NASA Goddard Space Flight Center, Greenbelt, MD, June 1975, 382 pp, $1.95.

"Auroral Electrojet Magnetic Activity Indices AE(11) for 1973," by Joe Haskell Allen, Carl C+
Abston and Leslie D. Morris, National Geophysical and Solar-Terrestrial Data Center, Boulder, CO,
June 1975, 144 pp, $210 (microfiche only) +

"Synoptic Observations of the Solar Corona during Carrington Rotations 1580-1596 (11 October 1971
- 15 January 1973)," {Reissue of UAG-48 with quality images], by ReAs Howard, M.J« Koomen, DeJe
Michels, Re Tousey, CeR. Detwiler, DsE. Roberts, ReTs Seal, and J«D. Whitney, U.S. Naval Research
Laboratory, Washington, DC, and R.T. Hansen and S.F. Hansen, C.J» Garcia and E- Yasukawa, High
Altitude Observatory, NCAR, Boulder, CO, February 1976, 200 pp, $4.27.

"Catalog of Standard Geomagnetic Variation Data," prepared by NOAA Environmental Data Service,
Boulder, CO, August 1975, 125 pp, $1.85.

"High-Latitude Supplement to the URSI Handbook on lonogram Interpretation and Rediction," edited
by W.R. Piggott, British Antarctic Survey, c/o Appleton Laboratory, Slough, UK, October 1975, 294
pp, $4400.

"synoptic Maps of Solar Coronal Hole Boundaries Derived from He 11 304A Spectrohel iograns from the
Manned Skylab Missions," by JsD. Bohlin and DeM. Rubenstein, U.S. Naval Research Laboratory,
Washington, DC, November 1975, 30 pp, $0.54.

"Exper Imental Comprehensive Solar Flare Indices for Certain Flares, 1970-1974," by Helen W. Dodson
and E. Ruth Hedeman, McMath-Hulbert Observatory, University of Michigan Pontiac, MI, November
1975, 27 pp, $0.60.

"Description and Catalog of lonospheric F-Region Data, Jicamarca Radio Observatory (November 1966
- April 1969), by WeLe Clark and T.E+ Van Zandt, NOAA Aeronomy Laboratory, Boulder, CO, and J.P.
McClure, University of Texas as Dallas, Dallas, TX, April 1976, 10 pp, $0.33.

"Catalog of Ionosphere Vertical Soundings Data," prepared by NOAA Environmental Data Service,
Boulder, CO, April 1976, 130 pp, $2.10.

"Equivalent lonospheric Current Representations by a New Method, Illustrated for 8-9 November 1969
Magnetic Disturbances," by Y. Kamide, Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, CO; HeW. Kroeh!, Data Studies Division, National
Geophysical and Solar-Terrestrial Data Center, Boulder, CO; M. Kanamitsu, Advanced Study Progran,
National Center for Atmospheric Research, Boulder, CO; Joe Haskel! Allen, Data Studies Division,
National Geophysical and Solar-Terrestrial Data Center, Boulder, C0; and'Se-I Akasofu, Geophysical
Institute, University of Alaska, Fairbanks, AK, April 1976, 91 pp, $1-60 (microfiche only).

|




EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM
12

OMT —= 250 nT

ELECTRIC POTENTIAL IONOSPHERIC CURRENT
7 300 30
12

JOULE HEATING

TOTAL

Au, = 5 W/m?
2.55 x 10! 2 ’

58

Agy= 4% 107 7Asm?



EQUIVALEN

T CURRENT
12

ELECTRIC

POTENTIAL

12

LIEN |
Nice

08

A® =10kv

JOULE HEATING

TOTAL

©

3.60 x 1020 00

uy = 5 mW/m?

54

EQUIVALENT CURRENT SYSTEM

Ay = 50000A

00

IONOSPHERIC CURRENT
7 2900

12

FIELD-ALIGNED CURRENT
7 2900
12

Ady 4% 1077 Asm?



140002

8Zé6I'6IYVN
b2 sl ai

9

82 6I'8IYVN
Oo si 2 9 0

B26 LIYVAN
gi 29 oO

rn a

T

a

piotiaiatiartinr

a

<7] HLIWS LYO4
axa AAI AVH

MOONVSAW

AVYYNWIW LYOs

NVAM2AdIHO LYO4
Ao ALIO WOINVYN

saxq SONSGIAOYNd LYOS

Bora s-t SAINMMOTTSA

Ava A9dINEWV9
= AVG SLATOSSY

aii ti a. |i Joa

LNANOdWIOD “4X
NIVHD VLYsE1V

16


EQUIVALENT CURRENT

EQUIVALENT CURRENT SYSTEM

50°

08

Ay = 500004

IONOSPHERIC CURRENT

FIELD-ALIG'!

NED CURRENT

TOTAL

6.86 x 10

Maye 4% 1077 Asm?





EQUIVALENT CURRENT
12

JOULE

HEATING

TOTAL
1.35 x 10

EQUIVALENT CURRENT SYSTEM

Tr 2300

Ay = 500004

IC CURRENT

FIELD-ALIGNED CURRENT

7 2300

Age 4X 1077 A/m?



APPENDIX A
IMS Meridian Chain Workshop

Oh March 9-11, 1982, a workshop on this particular
project, sponsored by National Geophysical Data Center
(NGDC), was conducted in Boulder, Colorado. This work~
shop was jointly organized by Y. Kamide and H. W. Kroehl,
and was attended both by representatives of the IMS mer-
idian chains and by scientists who provided computer al-
gorithms to model the current distribution. The objec-
tive of the workshop was to discuss the dynamics of mag-
netic perturbations recorded during the March 17-19,
1978, period, to discuss some of the results as well as
future works using that data base, and to estimate the
global distribution of electric fields and currents, on
an interactive basis through computer terminals located
in the workshop room. The terminals were connected to
a CDC CYBER-750 which is the main computer system in
the NOAA Boulder Laboratories. In particular, this was
perhaps the first attempt to provide each workshop part-
icipant with the ability to change the input parameters
and assumptions and to see the effects of the changes
on the output from a numerical modeling.

The procedure used is outlined as follows: The
distribution of the magnetic perturbations in the geo-
magnetic north-south and east-west components relative
to the average level of March 12, 1978 (the quietest
day in March 1978) was used to calculate the equivalent
current function in the ionosphere using a computer
method developed by A. D. Richmond of the NOAA Space
Environment Laboratory. From the current function and
each of several different ionospheric conductivity mod-
els (e.g., the model compiled by R. W. Spiro of Rice
University), the electric potential, the ionospheric
and field-aligned currents, and Joule heat energy were
then determined using the algorithm developed by Y.
Kamide.

The workshop was conducted alternating between
brief presentations by the participants and interactions
with the data set through the computer terminals. G.
Rostoker of the University of Alberta, Canada, pointed
out the need to adjust the fitting program for the eq-
uivalent current function in order to account for the
continuity of the auroral electrojets through regions
of sparse data. He also argued the importance of the
Z component for locating the electrojets, something not
included in our original data base. B.-H. Ahn and S.-I.
Akasofu, both of the University of Alaska, showed the
possibility of estimating a better result for the glob-
al electric potential by using more realistic conduct-
ivities including local enhancements associated with
local geomagnetic perturbations. As one of the out-
comes of the joint study and the workshop, a paper de-
scribing the data set and some of the initial results
has been accepted for publication (Kamide et al., 1982).

11

An important agreement was reached at the workshop
to transfer all the collected and rearranged data on
magnetic tape to WDC-A for STP for further distribution
to the scientific community. The data base includes
three days of 5-minute magnetometer data in the geo-
magnetic X, and Y, components from stations of six IMS
meridian cHains pTus some standard observatories, a
total of 71 stations above 50° in geomagnetic latitude
in the Northern Hemisphere. The Z component data are
available in a digital or analog form (depending on
stations) on request to the representative of each
meridian chain or from WDC-A.

APPENDIX B
THE DATA UTILIZATION WORKSHOP CONCEPT

The IMS Meridian Chain Workshop at NGDC was the
first Data Utilization Workshop (DUW), an effort to
bring the research community and the data center closer
together and improve the access to high-quality data
collections and analytical programs and facilities.
Simply stated, the core functions of a data center are
to collect, archive, disseminate, publish and analyze
data. The analysis function is essential in addressing
questions of data quality assessment, data usability,
development of future programs and plans to meet new
data needs of the scientific community. NGDC's analysis
capabilities were developed over several years by resi-
dent staff professionals and visiting guestworkers,
who developed programs and data products in pursuit of
their scientific interests. Building on this founda-
tion, the DUW's concept is to expand the data center's
historical functions to include the collection, prepar-
ation and evaluation of a very good data base and to
improve our understanding of an environmental phenomenon
through the interactive analysis of these data and pro-
grams by many scientists. Some of the advantages to
the scientists of holding this type of focused workshop
at the data center are the human and computer resources
in residence there and the availability of complement-
ary data to answer questions that arise. Advantages to
the data center include the expansion of their software
library, improved quality assessment of the workshop
data, increased utility of the data, and improved user
relations. Each participant expressed his opinion that
this workshop was extremely successful scientifically
and encouraged the data center to expand the DUW concept
in this and other fields.

|



EQUIVALENT CURRENT

ELECTRIC POTENTIAL

7% 2200

JOULE HEATING

1.57 x 102!

EQUIVALENT CURRENT SYSTEM

Ay = 500004

IONOSPHERIC CURRENT

3A/m

FIELD-ALIGNED CURRENT

7% 2200

4

Maye 4% 1077 Asm?

ean

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EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM
12

Tr 1900

Wp
vi

“/ 4 UY [F a
4

ea

S2a

ns
KH

Ay = 50000A

|ONOSPHERIC CURRENT

A® = 10kv

00

JOULE HEATING

Tr 1900 Tr 1900
12



EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

7 00
12 12

=, 50°

&

Ay = 500004

O MLT —— 250 nT 00

ELECTRIC POTENTIAL 1ONOSPHERIC CURRENT

Tm 00
12

—_
3A/m

00

HEATING FIELD-ALIGNED CURRENT

m7 000

©

Auy = 5 mW/m? Agyj= 4X 1077 Asm?

61


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826I'6IYVN
a

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82 6I'8lYVN
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fe)

B26 LVYVN
gsi zl

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a

a

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NOSdWOHL

moved

THIHOYNHS LYOS

ANIOd OWIMS3
LAIN NIXNVY

SMV SVE

Ave AT1Ad

LNSNOdWoo “x

NIVHOD THHOYNHD LYOSs

18


12 re 400

EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM |
|

Ay = 50000A |

O MT —= 250 nT
ELECTRIC POTENTIAL IONOSPHERIC CURRENT
7 400 7 400
12

3A/m

00

FIELD-ALIGNED CURRENT

12

! )\

|
Mayet 4X 1077 Asm?

Auy=5 mW/m2
35




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9

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a al

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po tri tiiti

a

OVNSSHVSSYVN

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@VHLGOS

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SANNHL

LNANOdWOO wy
NIVHO GNWINASY9

al






EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM
re 400

nS 50°

So

Le
=

( #

Ay = 500004

(ONOSPHERIC CURRENT

7 400
12

JOULE HEATING

Auy= 5 mW/m?

Aye 4X 1077 Asm?
83


EQUIVALENT CURRENT

O MLT

—= 250 nT

POTENTIAL.

JOULE

HEATING

A® = 10kv

Ay = 500004

00

IC CURRENT

Auy= 4% 1077 A/m?



EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

7a 800
12 12

- 50°
MQ
6 c bea
a L
fy
| ~
Ay = 50000A
OMT —~ 250 nT °°
ELECTRIC POTENTIAL IONOSPHERIC CURRENT

3A/m

FIELD-ALIGNED CURRENT
800

TOTAL
9.23 x 1020 00

Auy = 5 mW/m? Ady= 4% 10° 7Asm?



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826l ‘81 UV

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29


vy . L 2n4t cay” yle) (4)
n Up tT Re n
where
vy = 2 vy, (0A)
n n
a= Re + 10 km
= 4m x 1077 H/m
0

Ionospheric Conductivity

At present there is no way to monitor continuously
the global distribution of the ionospheric conductivity.
Recently, several conductivity models have been develop-
ed based on radar and satellite measurements of precip-
itating electrons (e.g., Vanyan and Osypova, 19763
Wallis and Budzinski, 1981; Vickrey et al., 1981; Spiro
et al., 1982). In this report it is assumed that the
conductance, that is, the height-integrated jonospheric
conductivity, has two components: one is a background
conductance of solar ultraviolet origin and the other
simulates an enhancement presumably due to substorm-
associated particle bombardment. We may call the form-
er the quiet time conductance and the latter auroral
enhancement conductance.

For the background conductance, we follow the
quiet time distribution for equinoctial months, as de-
scribed in equations (19) and (20) of Kamide and
Matsushita (1979). For the auroral enhancement, we use
an empirical model based on the work of Spiro et al.
(1982) with updated improvements. This is because the
height-integrated Hall and Pedersen conductivitigs (oy
and £)) in this model are tabulated at every 1-2
(in 1Bti tude) and 1 hour (in MLT) for each level of aur-
oral electrojet activity measured by the AE index.
Spiro et al. (1982) used data of precipitating particle
energy flux and average electron energy obtained from
the Atmosphere Explorer satellites (AE-C and AE-D)
along with the dependence of the height-integrated con-
ductivities on the characteristic energy of precipitat-
ing electrons obtained by Vickrey et al. (1981).

It should be noted that at two instants with the
same value of the AE index, the auroral distribution
and the conductivity distribution, as well as the cur-
rent patterns in the polar region, may be significantly
different. Thus, although the ionospheric current pat-
terns are only weakly dependent on the choice of the
conductivity (e.g., Kamide and Richmond, 1982), the
following adjustment is employed in the use of the con-
ductivity model: by assuming that the latitude of the
maximum equivalent current strength coincides with the
latitude of the highest Hall conductivity, a latitudin-
al shift is made for the entire conductivity distribu-
tion whenever a difference between the two latitudes of
the maxima is found.

Electric Potential

During the last several years, different techniq-
ues have been developed to analyze global magnetometer
data in order to infer the three-dimensional distribu-
tion of electric currents around the earth (e.g.,
Kisabeth, 1979; Mishin et al., 1980; Kamide et al.,
1981). These methods take the distribution of magnetic
perturbation vectors observed on the earth's surface as
the input and try to estimate the distribution of jono-
spheric and field-aligned currents and other related
quantities as outputs for a given model of ionospheric

conductivities. Akasofu et al. (1981) compared the
algorithms of Kisabeth (1979) and of Kamide et al.
(1981) using daily average data from the Alaska merid-
ian chain as input. They found that the gross distri-
bution patterns of both ionospheric and field-aligned
currents computed from these techniques agree satisfact-
orily, lending credence to the reliability of such meth-
ods in inferring the actual electric currents from the
data. In this report, we employ an improved version of
the computer algorithm developed by Kamide et al.

The height-integrated ionospheric current can be
considered to consist of two elements. The toroidal
(solenoidal) current J is related to the equivalent
current function p as

Je, = -
Te asinoar
(5)
Jr = Oe
TA aa6

The other part, the poloidal current J, can be consid-
ered as a closing current for field-alfgned currents jy.
(Note that j, = div J, and div J, = 0 by definition and
that j,, and 4 together produce To ground magnetic var-
jation under the assumption of magnetic field lines
penetrate vertically into the horizontal ionosphere).
The associated electric field E is derivable from an
electrostatic potential 6. A partial differential equa-
tion for ® in terms of p can then be written as

2,
ao p 2%

ae ae
Aspe + Bag t Cae t Oars F (wer) (6)

where

A= sin 6+ Ey

= 2 (sing + a
B= 5 (sing ty) + 3x Bp

C = Zy/sine
= 2 Up ysine) = 26
p= - & (ny/sine) - $5 2p
= 2 tgine aby + 2
F = gq(sino 39) * sino a

The above differential equation (6) is to be num-

erically solved with approximate boundary conditions:
@(0,A) = 0 at the pole

(8)

2e(n/2.1), 0 at the equator

Once the electrostatic potential is obtained, the elec-
tric field E is derivable from the potential @ as

E=- grado. (9)

___ Practicatly, we solve (6) numerically by a finite
djfference schgme over a network of grid points spaced
1 in @ and 15° in A. As discussed by Kamide et al.
(1981), it was assumed in deriving (6) that the magnet-
ic contributions of the magnetospheric ring currents
and tail currents to y can be neglected and geomagnetic
field lines are effectively radial. The breakdown of
these assumptions at lower latitudes probably invali-
dates the calculated potential values at low latitudes.

(1981).





1 (0 [ oveirzanion oF ] |
| HAD (or X&Y)
ly } |
| GENERATION OF 1 @)
| AXm & AYm \ AE (Tl)
(4) |
| MAGNETIC poreNTiAL} | Fm
| CURRENT FUNCTION} |
|__FiowospHERic
: (an
| © levecraic potential) |
| ELECTRIC FIELD |
|
| (6) : |
IONOSPHERIC b——--_~ 4
CURRENT | f 7
| gE 3
| (8) J souue neat | |, movie 8
| lNercy rare | | > 12 FILM &
1 7 reto-auenen | B 8
| CURRENT 8 s|
EPEAT
|

Fig. 2

(8) Estimation of Joule heating rate, which is
the scalar product of the ionospheric current and
electric field vectors.

(9) Repetition of these steps for each time in
the entire period and preparation of a master 35-mm
film to be printed on 16-mm films.

Additional details of the computations in steps
(4) through (8) are described briefly in the following:

Current Function

The observed magnetic data from the 71 stations
were fitted to a magnetic potential function V which
is represented by a spherical harmonic series with
longitudinal wave numbers m from 0 to 6 and order n=m
to 56, as expressed by the standard form:

6 56
V(e,rAje rE (an cos m + bn sin mA)Pn(cose)
m=o n=m

(1)

where @ and X are colatitude and east longitude (meas-
ured from midnight), respectively, in the eccentric
dipole coordinate system. A11 terms involving assoc-
jated Legendre polynomials P_ with even (n-m) are omit-
ted from the series, except the n=m term, as the odd
terms alone are basically sufficient to represent the
northern hemispheric potential. The X_ and Y_ compon-
ents at each station are expressed by" m
apm

TM os n
cos mA + by sin m\) “ae (2)

Flow chart describing the important steps in the present project.

pm

(3)

a mM oe _ pm n
Yar BEM (a, sin m - by cos mA) sind

The choice of these maximum n and m values is based on
trial and error tests with a varjety of, values. There
are in total 358 coefficients, a, and b., to be deter-
mined in the harmonic series (1)° ”

In seeking an appropriate potential function V,
it is required here that the potential vary smoothly
in space between stations. We started with the algor-
ithm of Richmond et al. (1979), which performs a least-
squares fit of the negative horizontal gradient of V to
the observed magnetic variations, with additional con-
straints to provide smooth interpolations between sta-
tions. We found that the results obtained from this
algorithm could be improved by making several ad hoc
modifications to the smoothing constraints, primarily
by increasing the smoothing in longitude with respect
to smoothing in latitude. This permitted a reduction
in the maximum m value and an increase in the maximum
n value without increasing the total number of coeffi-
cients. The root-mean-square difference between com-
puted and observed magnetic perturbations is typically
15%. However, at certain times the discrepancy rises
above 20%.

It is then assumed that there is a relatively
small internal contribution to the magnetic potential
caused by a perfectly conducting layer 300 km below BS
earth's surface. The remaining external potential V
is extrapolated to 110 km altitude and converted to an
equivalent ionospheric current function wy by the stand-
ard procedure:



EQUIVALENT CURRENT

12

i}

ELECTRIC

12

MLT —= 250 nT

POTENTIAL

EQUIVALENT CURRENT SYSTEM

7% 700

Ay = 50000A

00

IONOSPHERIC CURRENT

3A/m

FIELD-ALIG:

NED CURRENT

Agy= 4% 1077 A/m?

—



Luoood

be

B26I'6lUVN
gl 29

826I'SlYVN
o gi 2 9 O

826 LIYVN
gi zi 9 0

re

ee

——

ptuitis

14

it

pa tii tid

pitti

pati

LNSNOdWOO MA
NIVHO VLYSd1V

ondgs7
MOONVSW

AVEYNWOW LYOs

NVAMAdIHO LYO4
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HLIWS LYO4
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BONACIAONd LYOS
SsINMMOTISA

Ava S9CINSWVO

~ AVG SLNIOSSY

17


REFERENCES

AKASOFU, S.-I., 1981 Comparison of two modeling methods for three dimension-

Y. KAMIDE, and al current systems, J. Geophys. Res., 86, 3389.

J. L. KISABETH

COLE, K. D. 1963 Eccentric dipole coordinates, Australian J. Phys., 16,
423,

KAMIDE, Y., and 1979 Simulation studies of ionospheric electric fields and

S. MATSUSHITA currents in relation to field-aligned currents,
1. Quiet periods, J. Geophys. Res., 84, 4083.

KAMIDE, Y., and 1982 Tonospheric conductivity dependence of electric fields

A.D. RICHMOND and currents estimated from ground magnetic observations,
J. Geophys. Res., 87, 8331.

KAMIDE, Y., 1981 Estimation of ionospheric electric fields, ionospheric

A. D. RICHMOND, and currents and field-aligned currents from ground mag~

S. MATSUSHITA netic records, J. Geophys. Res., 86, 801.

KAMIDE, Y., 1982 Global distribution of ionospheric and field-aligned

B.-H. AHN, currents during substorms as determined from six IMS

S.-I. AKASOFU, meridian chains of magnetometers. Initial results,

W. BAUMJOHANN, a. Geophys. Res., 87, 8228.

—, FRIIS-CHRISTENSEN, —_

H. W. KROEHL,

H. MAURER,

A. 0. RICHMOND,

G. ROSTOKER,

R. W. SPIRO,

J. K. WALKER, and

A. N. ZAITZEV

KISABETH, J. L. 1979 On calculating magnetic and vector potential fields due
to large-scale magnetospheric current systems and in-
duced currents in an infinitely conducting earth, in
Quantitative Modeling of Magnetospheric Processes, ed.
by W. P. Olson, Amer. Geophys. Union, pp. 473-498,

MISHIN, V. M., 1980 Electric fields and currents in the earth's magneto-

A. D. BAZARZHAPOV, and sphere, in Dynamics of the Magnetosphere, ed. by S.-I.

G. V. SHPYNEV Akasofu, D. Reidel, pp. 249-268.

RICHMOND, A. D. 1979 Magnetic potential plots over the northern hemisphere

H. W. KROEHL, for 26-28 March 1976, WDC-A Report UAG-71.

M.A. HENNING, and

Y. KAMIDE

SPIRO, R. W.,. 1979 Precipitating electron energy flux and auroral zone

P. H. REIFF, and conductances—An empirical model, J. Geophys. Res. ,

L. G. MAHER, JR. 87, 8215.

VANYAN, L. L., and 1976 The electrical conductivity of the polar ionosphere,

I. L. OSYPOVA Geomag. Aeronomy, 15, 847.

VICKREY, J. Fe, 1981 The diurnal and latitudinal variation of auroral zone

R. R. VONDRAK, and ionospheric conductivity, J. Geophys. Res., 86, 65.

S.J. MATTHEWS

WALLIS, D. D., and 1981 Empirical models of height integrated conductivities,

E. £. BUDZINSKI J. Geophys. Res., 86, 125.

12



CHANGES IN THE GLOBAL ELECTRIC FIELDS AND CURRENTS FOR MARCH 17-19, 1978
FROM SIX IMS MERIDIAN CHAINS OF MAGNETOMETERS

by

Y. Kamide?>?, H.W. Kroehl?, A. D. Richmond’, B.-H. Ahn*, S.-I. Akasofu",
W. Baumjohann®, E. Friis-Christensen®, S. Matsushita’, H. Maurer®,
G. Rostoker?, R. W. Spiro®®, J. K. Walker'!, and A. N, Zaitzev??

PART 1

I. INTRODUCTION

In the first half of this century the pioneering
work of K. Birkeland, soon followed by S. Chapman and
H. Alfvén, attempted to infer the electric current sys-
tem responsible for ground magnetic disturbances.
Studies of ground-based magnetic records have been wide-
ly used to examine processes ocurring in the magneto-
sphere and ionosphere in terms of the growth and decay
of the three-dimensional current system in the polar
region which consists of ionospheric currents and field-
aligned currents. In the past, however, because the
magnetometer shows the complicated superimposed effect
of various types of currents, it was not possible to de-
termine ionospheric currents and field-aligned currents,
separately. Studies on this subject were primarily
based on the so-called equivalent ionospheric current
system. The equivalent current system can be determined
by assuming that all overhead currents contributing to
ground-based magnetic perturbations flow in a spherical
shell (i.e., the ionosphere) concentric with the earth.
During the last two decades there have been a number of
new techniques to measure the field-aligned current-
density, electric fields, etc., in and near the iono~
sphere. However, although these ‘direct’ measurements
are most valuable, it is still not possible to construct
the distribution of the three-dimensional currents with-
out a number of assumptions. Furthermore, it is not
practical to construct instantaneous three-dimensional
current distributions from polar orbiting satellite
measurements of particles, fields and/or currents.
Therefore, it has become a compelling task for us to
develop methods which could determine the current and
field distribution on the basis of ground magnetometer
data.

Owing to the significant improvement of the ground
magnetic networks, as well as various numerical tech-
niques developed during the last decade, it has now be-
come possible to estimate the three-dimensional current
system over the polar region during individual magneto-
spheric substorms with a relatively high time resolution.
It has taken more than half a century to quantify the
pioneering concepts of Birkeland, Chapman and Alfvén,
although improved accuracy of the estimation procedures
is still a desirable goal.

In 1973, the International Association of Geomag-
netism and Aeronomy (IAGA) established a working group
on the Geomagnetic Meridian Project to evaluate the
need for improved magnetometer networks at high lati-
tudes. The working group stressed the importance of
coordinated observations of magnetic fields in the
polar region, particularly along meridian lines to be
compared with simultaneous satellite, rocket and radar
observations. Then, during the International Magneto-
spheric Study (IMS), a joint effort was made to set up
magnetometer chains along several magnetic meridians.
As a result, seven meridian chains were operating in
1978 and 1979: the Alaska chain, the Alberta chain,
the Fort Churchill chain, the Greenland chain, the
Scandinavia chain, the IZMIRAN chain, and the SibIZMIR
chain. In addition to the projects conducted by indiv-
idual meridian chain groups, the IMS meridian chain
group has as a whole agreed to study jointly the growth
and decay of ionospheric currents and field-aligned
currents for magnetospheric substorm events.

The purpose of this report is to present some of
our products: calculated ionospheric electric poten-

Space Environment Laboratory, NOAA, Boulder, Colorado 80303

On leave of absence from Kyoto Sangyo University, Kyoto 603, Japan

National Geophysical Data Center, NOAA, Boulder, Colorado 80303

Geophysical Institute, University of Alaska, Fairbanks, Alaska 99701

Institut fiir Geophysik der Westfalischen Wilhelms-Universitat, Corrensstr. 24, D-4400 Minster, Federal
Republic of Germany

Meteorological Institute, Division of Geophysics, DK-2100, Copenhagen, Denmark |
High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado 80307 i
(which is sponsored by the National Science Foundation) ‘
Institut fur Geophysik und Meteorologie, TU Braunschweig, D-3300 Braunschweig, Federal Republic of Germany i
Institute of Earth and Planetary Physics and Department of Physics, University of Alberta, Edmonton, ;
Canada T6G 201

10 Department of Space Physics and Astronomy, Rice University, Houston, Texas 77251

11 Earth Physics Branch, Department of Energy, Mines and Resources, Ottawa, Ontario, Canada KIA OY3
(Contribution 1028 from Earth Physics Branch)

Polar Geomagnetic Research Laboratory, IZMIRAN, Troitsk, Moscow Region 142092, U.S.S.R.



EQUIVALENT CURRENT
12

HEATING:

TOTAL
1.97 x 101!

ea)

00

67

©

EQUIVALENT CURRENT SYSTEM

Tr 1200
12

~~

y

nl nent

&

Ay = 500004

00

IONOSPHERIC CURRENT

FIELD~ALIG

Tr 1200

Aye 4x 107% Asm? |


SLEI6IYVN SLESIYVN BZ6I'ZIYVA
bz si zi o9 oO Bs 2 9 oO gs 2 9 Oo

a

MOYOs

==! ONVSSNY

LYU0002

ILLYVW

Aewst—-—| OAS

S3NNM

22

at---| SVASHV AS

VAONNOra

ONNS31V AN
=| GHON

L pion ta a bai tii Pee Pe Pa ta pi tid

LNSNOdWOD “Xx
NIVHO VIAVNIGNV9OS



EQUIVALENT IONOSPHERIC CURRENT VECTORS
12

MARCH 19, 1978
1200 UT

00 MLT

Fig. 4c
the grid points.

Equivalent current vectors calculated at

PEDERSEN CONDUCTIVITY

2

1200 UT
MARCH 19, 1978

CONTOUR INTERVAL
2 mhos

00 MLT

Fig. 4d

06

MARCH 19, 1978

1200 UT

ELECTRIC POTENTIAL

Fig. 4e

CONTOUR INTERVAL
10 kv

Electric potential contours.

HALL CONDUCTIVITY

00 MLT

Assumed height-integrated Pedersen and Hall conductivities.

CONTOUR INTERVAL

4 mhos

ence een



JU 0002

826l ‘El YVW

ve Bi él 9

e)

826l ‘81 UV
a)

ie)

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a

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rit i

pitiitiirtin

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bo

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O T .



ELECTRIC FIELD VECTORS

MARCH 19, 1978 2
1200 UT ;

00 MLT

Fig. 4f Electric field vectors.

PEDERSEN CURRENT VECTORS

00 MLT

Fig. 4h Pedersen

MARCH 19, 1978

IONOSPHERIC CURRENT VECTORS

MARCH 19, 1978
1200 UT

06

00 MLT

Fig. 4g Ionospheric current vectors.

HALL CURRENT VECTORS

1200 UT

2 im 00 MULT

and Hall current vectors.

9

q
)

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i
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j
if
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EQUIVALENT CURRENT
12

2.93 x 10

11

Auy=5 mW/m*

EQUIVALENT CURRENT SYSTEM

7% 1600

7% 1000

12

Ay = 50000A

IC CURRENT

‘hy,

3A/m

FIELD-ALIGNED CURRENT

7% 1600

12

95

Auy= 4X 1077 A/m

20




EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

12 7 800
12

50°

Ay = 50000A

IONOSPHERIC CURRENT

12

7 e000

JOULE HEATING

TOTAL

= 7 2
10 Ady= 4% 1077A/m
6.38 x 10





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8261 ‘6l YVW

bv al él i)

fe)

826 BI YVW

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8261 ZI YW
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EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

78 1400

08.

Ay = 500004

ELECTRIC POTENTIAL IONOSPHERIC CURRENT

7% 1400 7 1400

08

FIELD-ALIGNED CURRENT

7 1400

12

TOTAL
Au, = 5 mW/m? Muy 4% 1077 Asm?

8.60 x 10 93


PART 3

The Hourly Plots of Observed Magnetic Perturbation
Vectors, Equivalent Ionospheric Current Systems,
Estimated Ionospheric Vectors, Joule Heating Rates,
and Field-Aligned Currents

Out of the various outputs shown in Figures 4a-j,
five plots (equivalent ionospheric current system,
electric potential, ionospheric current vectors, Joule
heating rate, and field-aligned current density) as
well as the distribution of observed magnetic pertur-
bations (in the form of their equivalent currents) are
displayed every 1 hour for the 3-day interval. The
outermost circle represents 50° N in eccentric gipole
latitude, with the other other circles every 10°. Date
and Universal Time are marked for each diagram: 76 =
March 17, 77 = March 18, and 78 = March 19, 1978.

31



8261 ‘6l YVW
rz sl 2 9

(0)

826 ‘SI YVW
al 2

ie)

826] ZI YVAN
sla 9

ie)

TMT

rr a

re

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re re

ritiirtir 1

potr i tir tin

pu fyi iit

BOVYOHONY

39371109

NOWNA LYOS

SOVTHA OILOYV

MIANNI

Add AdVo
YOSYVH SHOVS
ANIOd NOSNHOP
Ava GINOW
NaSHOVS!

vosY"na

LNSNOdWOO 4,
NIVHO VYSV1V

15


EQUIVALENT CURRENT EQUIVALENT CURRENT SYSTEM

12 Te 400

50°

Ay = s0000A

0 MLT = 250 nT °°

ELECTRIC POTENTIAL IONOSPHERIC CURRENT

—
3A/m
00
k
JOULE HEATING FIELD-ALIGNED CURRENT |
Te 400 2 7 400 12

TOTAL
1.21 x 101! 00

; Maye 4% 1077 Asm?
59


tials, ionospheric and field-aligned currents, and
Joule heating rates by the ionospheric currents. Also
included are the measured ground magnetic perturbations
on March 17, 18 and 19, 1978: from seventy-one sta-
tions. Part 1 contains brief comments on the method
used in the estimation of these quantities. Part 2
displays common-scale magnetograms in the X_ (geomag-
netic north) and Y_ (east) components from 41] the 71
stations. In PartTM3 are plots at hourly intervals of
the global distribution of these parameters. It is
hoped that these data sets provide the scientific com-
munity with new information to improve our understand-
ing of magnetospheric and ionospheric processes.

TI. QUTLINE OF THE PROJECT
Three consecutive days, March 17, 18 and 19, 1978,

were selected initially since the largest number of
magnetic stations of the six meridian chains were oper-

ating. (Unfortunately, the SibIZMIR chain was not oper-
ating in the spring of 1978, leaving a longitudinal gap
in the East-Siberia sector.) The geomagnetic index ZKp
on those days was 31-, 30- and 23, respectively. this
joint effort emphasizes particulafly the global scale
features, since small-scale features can be studied in
more detail by individual chains. The University of
Alaska group took the responsibility of assembling,
digitizing and formating the necessary data set (5-min-
ute average values) and also of modifying the original
computer codes for this particular project. For three
days in March 1982, the first workshop was conducted at
the National Geophysical Data Center in Boulder, Colo.,
which was attended by representatives from the IMS
meridian chains. A summary of the workshop as well as
the agreements reached at the Boulder workshop is de-
scribed in the Appendices A and B. An initial result
emphasizing an intense substorm on March 19, 1978, has
been published by Kamide et al. (1982).

Table 1

List of the magnetic stations whose data are used.

Station Name Geographic Eccentric Dipole Station Name Geographic Eccentric Dipole
Lat. long. Lat. —_Long. Lat. Long. Lat. Long.
Alaska Chain
35. Godthab 64.2 308.3 71.2 22.5
0. Eureka 80.0 274.3 89.0 325.3 36. Frederickshab 62.0 310.3 68.9 23.3
1, Isachsen 78.8 256.0 86.0 268.4 37. Narssarssuaq 61.0 314.6 67.4 27.9
2. Mould Bay 76.2 240.6 81.7 262.5
3. Johnson Point 72.5 241.7 78.7 276.1 Scandinavia chain
4. Sachs Harbor 72.0 234.7 77.3 268.0
5. Cape Parry 70.2 235.3 75.7 272.2 38. Nord 81.6 343.3 80.2 101.6
6. Inuvik 68.3 226.7 72.7 264.8 39. Ny Alesund 78.9 12.0 74.8 107.3
7. Arctic Village 68.1 214.4 70.5 251.6 40. Bjornoya 74.5 19.2 70.2 104.1
8. Fort Yukon 66.6 214.7 69.2 253.8 41. Skarsvag 71.1 25.8 66.3 105.1
9. College 64.7 211.9 66.9 252.9 42, Kunes 70.4 26.5 65.6 104.9
10. Anchorage 61.2 210.1 63.3 254.0 43. Kevo 69.8 27.0 64.9 104.8
44, Martti 67.5 28.3 62.6 104.0
Alberta Chain 45. Kuusamo 65.9 29.1 61.0 103.6
46. Borok 58.0 38.3 52.2 107.2
11. Resolute Bay 7467 265.1 83.3 311.5
12. Cambridge Bay 69.1 255.0 77.1 301.7 IZMIRAN chain
13. Yellowknife 62.5 245.5 69.6 294.1
14. Fort Providence 61.4 242.6 68.2 291.1 47, Heiss Island 80.6 58.0 72.3 135.3
15. Hay River 60.8 244.2 67.8 293.5 48. Karmakuly 72.3 52.5 64.7 125.1
16. Fort Smith 60.0 248.0 67.4 298.9 49. Dixon Island 73.5 80.6 64.3 144.6
17. Uranium City $9.6 251.5 67.4 303.6 50. Belyy Island 73.0 71.1 64.1 138.5
18. Fort Chipewyan 58.8 248.0 66.2 299.5 51. Kharasavey 71.5 67.5 62.8 135.1
19. Fort McMurray 56.7 248.8 64.2 301.4 52. Tambei 71.5 71.9 62.6 138.2
20. Meanook 54.6 246.7 61.9 299.6 53. Amderma 69.7 61.6 61.4 130.2
21. Leduc 53.3 246.6 60.6 300.0 54. Kamennyi 68.4 73.5 59.4 138.4

Fort Churchill Chain

22. Pelly Bay 68.5 270.5 77.4 327.4
23. Baker Lake 64.3 264.0 72.9 318.7
24. Rankin Inlet 62.8 267.7 71.6 324.6
25. Eskimo Point 61.1 265.9 69.8 322.5
26. Fort Churchill 58.8 265.9 67.5 323.0
27. Back 57.7 265.7 66.8 322.9
28. Thompson 55.0 263.0 63.6 320.0
29. Island Lake 53.9 265.3 62.6 323.1
30. Whiteshell 49.8 264.8 58.6 323.1

Greenland Chain

31. Thule 77.5 290.8 85.5 22.7
32. Upernavik 72.8 303.8 79.8 28.0
33. Umanak 70.7 307.8 77.4 29.5
34. Godhavn 69.3 306.5 76.2 25.5

Other stations

55. St. John's 47.6 307.3 55.4 14.0
56. Leirvogur 64.2 338.3 67.0 56.9
57. Kap Tobin 70.4 338.0 72.7 64.1
58. Hartland 51.0 355.5 52.0 65.9
59. Danmarkshavn 76.8 341.4 77.4 81.3
60. Niemegk 52.1 12.7 50.3 82.4
61. Abisko 68.4 18.8 64.7 97.2
62. Cape Chelyuskin 77.7 104.3 68.4 159.8
63. Tixie Bay 71.6 129.0 63.1 177.9
64, Yakutsk 62.0 129.7 53.3 181.5
65. Cape Wellen 66.2 190.2 64.8 230.3
66. Barrow 71.3 203.2 71.7 236.0
67. Sitka 57.1 224.7 61.6 272.6
68. Victoria 48.5 236.6 54.7 289.9
69. Great Whale River 55.3 282.2 64.3 344.8
70. Ottawa 45.5 284.5 $4.6 347.1



EQUIVALENT CURRENT SYSTEM

78 1200

Auy2 4% 1077 Asm?
91

ee oe


EQUIVALENT CURRENT
12

O MLT —= 250 nT

ELECTRIC POTENTIAL

)

TOTAL
2.14 x 19!

EQUIVALENT CURRENT SYSTEM
a)

Ay = 50000A

IONOSPHERIC CURRENT

Ade 4X 1077 A/mm?



EQUIVALENT CURRENT
12

0 MLT —= 250 nT

ELECTRIC POTENTIAL

JOULE

HEATING

TOTAL
4.04 x 1920

|_ ——~"_ Auy = 5 mW/m?
00

98

EQUIVALENT CURRENT SYSTEM

78 1900

50°

Ay = 500004

IONOSPHERIC CURRENT
ve 1900

FIELD-ALIGNED CURRENT
7a 1900

Muy 4X 1077 Asm?



EQUIVALENT CURRENT

0 MLT —

ELECTRIC POTENTIAL

250 aT

TOTAL

1.13 x 10!

EQUIVALENT CURRENT SYSTEM

50°
AGEX DA.
>
g
GY
SS
af Ay = 50000A

IONOSPHERIC CURRENT

Dem rseenencerap

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