,

I .

Space Sciences Laboratory University of California

Berkeley, California 94720

Distribution of t h i s document i s unlimited.

Response of the Geomagnetic Activity Index Kp t o the Interplanetary Magnetic Field

Kenneth H. Schatten and John M. Wilcox

Technical Report

Om Contract Nonr 3656(26) Project No. Mi 021 101

Pa r t i a l support from NASA Grant NsG 243 c

Series No. 8, Issue No. 22

Reproduction i n whole o r i n pa r t i s permitted f o r any purpose of the United States Government.

March 28, 1967

https://ntrs.nasa.gov/search.jsp?R=19670028472 2020-05-10T14:11:11+00:00Z

1.

Response of the Geomagnetic Act ivi ty Index

$ t o the Interplanetary Magnetic Field

Kenneth H. Schatten and John M. Wilcox

Space Sciences Laboratory

University of Cal i fornia

Berkeley, California 94720

Abstract

Interplane-bary magnetic f i e l d observations with IMP-3 during eight

so l a r ro ta t ions i n the l a t t e r half of 1965 have been compared with the

3-hour 5 index.

IMP-1 from three so l a r ro ta t ions i n the winter of 1963-4, indicating a

s t a b i l i t y i n the response of geomagnetic a c t i v i t y during these years near

solar a c t i v i t y minimum. The larger da ta sample i n the present inves t i -

gat ion reduces the probable e r ro r and del ineates some in te res t ing r e su l t s .

The average value of Kp decreases as the angle between the interplanetary

f i e l d and the e c l i p t i c changes from south t o north.

with the reconnection of interplanetary and geomagnetic f i e l d l i n e s as

suggested by Dungey.

t h e average value of the index % i s more l i n e a r than I$, as might be

expected.

In t h e time i n t e r v a l covered by these observations the average value of

i s cons is ten t ly higher i n sectors with interplanetary f i e l d directed away

from the sun than i n sectors with f i e l d directed toward the sun.

The r e s u l t s a re consistent with those obtained with

This i s consistent

A s a function of interplanetary f i e l d magnitude B,

The r e l a t ion can be described by < = (1.5 2 0.1) B + 0.7 t 0.5.

%

2 .

INTRODUCTION

The influence upon geomagnetic ac t iv i ty of the interplanetary magnetic

f i e l d observed by the magnetometer experiment on the IMP-3 satel l i te has

been studied. The results support an interconnection between the in te r -

planetary and geomagnetic f i e l d l ines as an important agent fo r transfer-

r ing the so la r wind energy i n t o geomagnetic ac t iv i ty , as suggested by

Dungey (1961) and l a t e r discussed by Levy e t al. (1964). -c-

Several observations and theories on the mechanisms f o r influencing

geomagnetic ac t iv i ty have been discussed i n our recent paper (Wilcox e t

-* a1 9 1967).

fur ther discussed the re la t ion between the interplanetary and geomagnetic

f i e lds .

of geomagnetic t a i l l i nes t o the interplanetary f i e ld on the basis t ha t

solar f l a r e electrons with low magnetic r ig id i ty readi ly appear i n the

geomagnetic t a i l . Patel e t al. (1967) have compared the geomagnetic index

% with the magnetosheath f i e l d observed by Explorer 12 and find t h a t high

% i s associated with a southward f ie ld . They report an "interesting, but

not conclusive" r e su l t t h a t a moderate "p i s associated with four cases of

a predominantly northward field, and point out t h a t t h i s r e su l t would not

be consistent with Dungey's magnetic merging theory. Zhulin (1966) has

discussed several mechanisms by which the interplanetary magnetic f i e l d

may p lay the ro le of an intermediary i n the interact ion between the solar

wind and the magnetosphere.

- After tha t paper was completed a number of authors have

Lin and Anderson (1966) have reported evidence for the connection

---

3 .

ANALYSIS

The IMP-3 (Explorer 28) s a t e l l i t e was launched on May 29, 1965 i n a

highly eccentric earth orb i t with an i n i t i a l apogee of 41.7 ear th r ad i i

at a sun-earth-apogee angle of 12OoE. This o rb i t allowed the s a t e l l i t e

t o sample the interplanetary magnetic f i e l d f a i r l y continuously from the

launch date u n t i l February, 1966, a t which time the s a t e l l i t e remained

within the magnetosphere and i t s t a i l during the en t i re orb i t , temporarily

preventing further interplanetary measurements.

interplanetary measurements were accumulated by t h i s time. A description

of the IMP-1 magnetometer, s i m i l a r t o the IMP-3 magnetometer, i s given by

Ness e t al. (1964).

Almost 4000 hours of

Due t o a malfunction no plasma data i s available. --- The interplanetary magnetic f i e ld during t h i s time interval was on

the average stretched out i n the ec l ip t ic plane along the Archimedean

s p i r a l angle as proposed by Parker (1958). This f i e l d could be classi f ied

f o r the most par t as being e i ther i n a sector with f i e l d directed predomi-

nantly toward the sun or i n a sector with f i e l d predominantly away from the

sun. "he sector pat tern i s evolving more rapidly than was the pattern

observed by IMP-1 (Wilcox and -9 Ness 1965) and IMP-2 (Fairf ie ld and -3 Ness 1967).

The influence of the interplanetary magnetic f i e l d and plasma on the

geomagnetic ac t iv i ty index $ during the quasi-stationary sector structure

observed by IMP-1 has been discussed by Wilcox e t al. (1967).

analysis i s now presented of the influence on geomagnetic ac t iv i ty of the

interplanetary magnetic f i e l d observed by IMP-3 during eight solar rota-

t ions , with the increased amount of data allowing fur ther resu l t s t o be

delineated. The method of analysis i s similar t o tha t of Wilcox -- e t al .

(1967) and i s discussed with reference t o Figure 1, which shows the re la t ion

A similar --

I

4.

between K

desired t o investigate the influence on a dependent variable

pendent var iable B, under conditions i n which 5 i s a l s o being influenced

by a number of other variables. The large amount of s c a t t e r i n the f igure

i s a t t r ibu ted t o the influence of these other variables, and it i s desired

t o i s o l a t e t he specif ic r e l a t ion between Kp and B.

sents a 3-hour value of Hp and the associated +hour average interplanetary

f i e l d magnitude.

precisely a t i t s actual value i n order t o avoid an overlap of the individual

points.

t o a given interplanetary stimulus i s then provided i n the following manner:

and the magnitude B of the interplanetary magnetic f i e l d . It i s

of an inde-

P

Each small dot repre-

Each (quantized) value of % i s p lo t ted close t o but not

A means of obtaining a s t a t i s t i c a l l y s ignif icant average 5 response

a ) Each solid c i r c l e represents t he average of all t he s m a l l

p-ints f a l i i n g w i t h i n a column which contains one-tenth of

t he t o t a l data.

Thus each so l id c i r c l e represents the average response of

5 t o a given small range of f ie ld magnitude, and has about

t he same s t a t i s t i c a l uncertainty as each of the other nine

large c i r c l e s ; a bar over 5 refers t o t h i s kind of average.

(The la rges t and smallest probable errors i n the ordinates

are shown.)

Although a well-defined re la t ion i s observed between I$

and interplanetary field magnitude, individual events

cannot be exp l i c i t l y predicted from t h i s analysis.

b )

- c )

Figure 2 i s a reproduction of Figure 2 of Wilcox L- e t al. (1967) showing

t h e r e l a t ion between $ and interplanetary f i e l d magnitude obtained during

t h r e e solar rotat ions observed by IMP-1 i n the winter of 1963-4.

solid c i r c l e s of Figure 1 of the present paper have been added as t r iangles .

The large

.

5.

The IMP-3 r e s u l t s a re consistent with the IMP-1 r e s u l t s , indicat ing t h a t

response of geomagnetic a c t i v i t y t o interplanetary f i e l d magnitude remains

qui te similar a t the time of IMP-3 even though the sector pa t te rn i s

evolving somewhat more rapidly.

(19th) eleven-year sunspot cycle, while a t the time observed by IMP-3

the sun was dominated by new-cycle ac t iv i ty .

IMP-1 observed near the end of the o ld

The index 5 i s a semilogarithmic measure of geomagnetic a c t i v i t y

while the index % i s a l i nea r measure of geomagnetic ac t iv i ty .

shows the r e l a t ion between % and interplanetary f i e l d magnitude B. It

can be seen t h a t "p f i t s a l i n e a r re la t ionship with B more closely than

does % (Figure 1).

by the equation $ = (1.5 f: 0.1) B + 0.7 2 0.5.

Figure 3

- -

The s t r a igh t l i n e drawn i n Figure 3 i s described

It was suggested by Wilcox -- e t a l . (1967) t h a t a southward interplane-

t a r y f i e l d has a greater geomagnetic effect iveness than a northward f i e l d ,

and it was pointed out t h a t a larger number and range of observations

would c l a r i f y the issue.

between % and the angle 8 , which i s the angle between the direct ion

of t he interplanetary magnetic f i e l d and e c l i p t i c .

now c l ea r ly del ineates an essent ia l ly monotonically decreasing value f o r

% as 8 changes from south t o north. This supports the suggestion by

Dungey (1961) and by Levy e t a l . (1964) of the interconnection of i n t e r -

planetary and geomagnetic f ie ld l ines .

Figure 4 shows the r e l a t ion observed by IMP-3

The l a rge r sample

-

Figures 5, 6 and 7 show the re la t ion between $ and the three so l a r

e c l i p t i c components of interplanetary magnetic f i e l d .

decl ine of

chnages from south t o north.

Figure 5 shows the

as the perpendicular component of the interplanetary f i e l d -

The small increase i n $ at the l a rges t

6 .

t

- Kp and northward component i s presumably r e l a t ed t o the r e l a t ion between

f i e l d magnitude shown i n Figure 1.

becomes la rge then the t o t a l f i e l d magnitude also becomes la rge , which

w i l l tend t o increase 'Gp as shown i n Figure 1. The tendency f o r Kp t o

increase as the magnitude of the f i e l d components increases can also be

observed i n Figures 6 and 7.

the radial component of the interplanetary magnetic f i e l d , and Figure 7

shows the r e l a t ion between l$, and the azimuthal component of the in t e r -

planetary f i e l d .

seen i n Figure 8, which shows t h e r e l a t i o n between 5 and the angle { , the azimuthal direct ion of the interplanetary f i e l d component p a r a l l e l

t o t he e c l i p t i c .

contrast t o t he r e l a t ion between % and the north-south angle 0 tha t was

shown i n Figure 4.

t h a t the values for sectors with interplanetary magnetic f i e l d directed

away from the sun are a s m a l l but s ign i f icant amount l a rge r than the values

of 5 f o r sectors with f i e l d toward the sun.

effect iveness of away sectors i s also evident i n the influence of

t he r a d i a l component of the interplanetary f i e l d shown i n Figure 6 and

the azimuthal component of the interplanetary f i e l d shown i n Figure 7.

If any s ingle component of the f i e l d

- -

- Kp and Figure 6 shows the r e l a t ion between

-

These f igures a lso show an asymmetry tha t i s more c lear ly -

- The r e l a t ion between I$ and the angle 9 i s i n marked

- - I$ i s t o f irst approximation independent of Q , except

- The greater geomagnetic

Kp Of

The difference between away and toward sectors i s shown i n more d e t a i l

i n Figure 9, which shows the average value of K f o r the away sectors and

f o r t he toward sectors within each Bartels so la r ro ta t ion . I n each solar

r o t a t i o n observed by IMP-3 the away sectors produced a l a rge r average value

of Kp than did the toward sectors .

IMP-3 the average value of 5 i n the away sectors was 1.94 f 0.15, and the

P

For the e n t i r e i n t e rva l observed by

7.

,

average value of Kp i n the toward sectors was 1.44 f 0.15. The probable

e r ro r s include an estimate of the e f f e c t of the conservation property of

$ (Chapman and Bartela, 1940).

Kp between away and toward sectors could be caused by differences i n the

average value of f i e ld magnitude B, north-south angle 8 o r solar wind

veloci ty V. If the re la t ion between Kp and solar wind velocity a t t he

time of IMP-3 was the same as tha t i n Figure 3 of Wilcox e t a l . (1967),

then an average solar wind velocity i n away sectors about 20 km/sec l a r g e r

than i n toward sectors could account f o r t he difference shown i n Figure 9.

Since solar wind veloci ty measurements a re not available from IMP-3 due t o

The difference i n the averwe value of

--

a malfunction t h i s p o s s i b i l i t y cannot be fur ther evaluated a t the present

t i m e .

not appear t o be caused by differences i n the average values of e i t h e r

f i e l d magnitude B o r north-south direct ion angle 0 . From Figure 1 one

The difference i n the average values of %shown i n Figure 9 does

can estimate t h a t i n order t o account f o r t he difference the away sectors

would need t o have an average value of f i e l d magnitude about 1.7 8

= 10 microgauss) l a rge r than the toward sectors, whereas the observed

average values of f i e l d magnitude i n toward and away sectors were equal

within the estimated probable error of f 0.2 I . Similarly from Figure

4 one can estimate t h a t t o explain the difference i n % the average value

of 8 i n away sectors would have t o be about 270 more southward (negative)

than i n toward sectors, whereas the observed average values of 8 i n toward

sectors was 0 f lo and the average value i n away sectors was 7 i lo.

(1 1(

A seasonal influence on the average value of 5 could a r i s e from the

tilt of the e a r t h ' s ro ta t iona l axis t o the e c l i p t i c .

hemisphere) winter an interplanetary magnetic f i e l d directed toward the

During (northern

!

sun and p a r a l l e l t o t h e e c l i p t i c would appear t o have a small southward

component as viewed i n a geomagnetic coordinate system, and thus from

the r e s u l t s of Figure 4 might be expected t o be s l i g h t l y more geomagnet-

i c a l l y e f fec t ive than an interplanetary f i e l d directed away from the sun

during the winter season.

reverse. Figure 9 includes portions of both summer and winter; i n the

l e f t (summer) port ion of t he figure t h i s e f f ec t of t h e tilt of the ea r th ' s

axis would cause the away ( so l id ) curve t o f a l l above the toward (dashed)

curve, but i n the r igh t (winter) portion of t he f igure t h e away curve

would be below the toward curve. Since the l a t t e r e f fec t i s not observed

i n Figure 9 t he tilt of the ea r th ' s axis cannot explain the r e su l t .

fu r the r discussion of t he average value of 5 as a function of a sector

s t ruc ture interpolated between the observations of IMP-1 and IMP-2 during

1964 w i l l be given i n a paper under preparation.

I n the summer these conditions would of course

A

The temporal r e l a t ion between the nearby interplanetary f i e l d magni-

tude and $ i s shown i n the top curve of Figure 10, which i s a crosscor-

r e l a t i o n of these quant i t ies as a function of time l a g . A posi t ive peak

i n correlat ion occurs a t a lag of zero, indicat ing tha t most of the response

occurs within the 3-hour period of . The sawtooth nature of the curve i s

probably re la ted t o the large scale-structure of the interplanetary f i e ld .

The bottom curve of Figure 10 shows the temporal r e l a t ion between t h e

north-south angle 0 of the f i e l d d i rec t ion and 5. l a g i s consistent with t h e re la t ion shown i n Figure 4 i n which the maximum

value of % occurs a t t he most southward (negative) value of 8 . In each

of t h e curves of Figure 10 the width of t he peak a t zero lag appears t o be

r e l a t e d t o the conservation property of the data (Chapman and Bartels, 1940).

!e

The minimum a t zero

9.

The top curve of Figure 11 shows an autocorrelation of the interplanetary

f i e l d magnitude, the middle curve i s an autocorrelation of 9 , and the

bottom curve i s an autocorrelation of . The autocorrelations of f i e l d

magnitude and of I$, i n Figure 11 show a re la t ive ly wide peak near zero lag

corresponding t o the wide peak i n t h e i r crosscorrelation i n Figure 10, while

the autocorrelation of 6 i n Figure 11 shows a much narrower peak near zero

lag corresponding t o the narrow peak i n the c' crosscorrelation of Figure 10.

Thus the widths of the peaks i n Figures 10 and 11 are mainly related t o the

s t ructure of the interplanetary f i e ld and not t o i t s interact ion with the

geomagnetic f ie ld .

5

SUMMARY

1. The average 5 response t o interplanetary f i e l d magnitude observed by

IMP-3 i n 1965 is consistent with the IMP-1 observations i n the winter

of 1963-4. - 'b and 2. A semilogarithmic tendency is observed i n the re la t ion between

f i e ld magnitudqwhereas the re la t ion between 5 and f ie ld magnitude

i s more l inea r , having the form % = (1.5 f 0.1) B + 0.7 f 0.5.

The average value of $ i s a decreasing function of the angle between

interplanetary magnetic f i e l d and t he e c l i p t i c as t h i s angle changes

from south t o north.

The above analysis supports the connection of intgrplanetary and geomag-

ne t i c f i e l d l i n e s as suggested by Dungey (1961).

I n each Bartels so la r rotat ion observed by IMP-3 the average value of

during away sectors was la rger than the average value of 5 during toward

sectors .

Crosscorrelation analysis suggests t h a t most of the geomagnetic response

to the interplanetary medium occurred during the 3-hour period of K

- -

3.

4.

Kp 5 .

6.

P'

10.

Acknowledgements. We thank N. F. Ness for sharing with us the obser-

vations of the IMP-3 magnetometer experiment and for several discussions.

This research was supported in part by the Office of Naval Research

under Contract Nom 3656(26), and the National Aeronautics and Space Admi-

nistration under Grant NsG 243.

express his gratitude for a National Science Foundation Fellowship and for

support from the National Aeronautics and Space Administration under Grant

NsG 695 for the University of Maryland summer program.

One of the authors (KHS) would like to

11.

REFERENCES

Chapman, S., and J. Bartels, Geomagnetism, pp. 582-586, Clarendon Press,

Oxford, 1940.

Dungey, J. W., Interplanetary magnetic f i e l d and the auroral zone, Phys. - - Rev. Letters, - 6, 47-48, 1961.

Fairf ie ld , D. H., and N. F. Ness, Magnetic f i e l d measurements with the IMP-2

s a t e l l i t e ,

Levy, R. H., H. E. Petschek, and G. L. Siscoe, Aerodynamic aspects of

magnetospheric flow, AIAA J. 2, 2065-2076, 1964. -- -

Lin, R. P., and K. A. Anderson, Evidence fo r connection of geomagnetic

t a i l l ines t o the interplanetary f i e ld , J. Geophys. Res., 71, - 4213-4217, 1966.

Ness, N. F., C. S. Scearce, and J. B. Seek, I n i t i a l resu l t s of the IMP-1

magnetic f i e l d experiment, J. Geophys. Res 69, 3531-3569, 1964. L -*’ -

Parker, E. N., Dynamics of the interplanetary gas and magnetic f ie lds ,

Astrophys. - - J. 128, 664-676, 1958.

Patel , V. L., L. J. Cahill, Jr., and A. J. Dessler, Magnetosheath f i e l d ,

geomagnetic index % and s t ab i l i t y of magnetopause, J. Geophys.Res., - - 72, 426-430, 1967.

Wilcox, J. M., and N. F. Ness, Quasi-stationary corotating structure i n

the interplanetairy medium, L J. Geophys. -*’ Res - 70, 5793-5805, 1965.

12.

Wilcox, J. M., K. H. Schatten, and N. F. Ness, Influence of interplanetary

magnetic field and plasma on geomagnetic activity during quiet-sun

conditions, - J. Geophys. - Res., 72, 19-26, 1967.

Zhulin, I. A., Geophysical effectiveness of solar corpuscular streams,

Geomag. and Aeronomy, 6 , 154-159, 1966.

1:3.

Figure Captions

Figure 1.

interplanetary magnetic f i e l d magnitudes. The s m a l l dots represent the

o r ig ina l 3-hour data values, and the so l id c i r c l e s are each the average

of 131 or ig ina l data points, as explained i n the t ex t . "he l a r g e s t and

smallest probable e r rors associated with the so l id c i r c l e s are indicated.

One gamma equals t en microgauss.

Scat terplot of the 3-hour Kp values with the +hour average

Figure 2.

points as small open c i r c l e s and the average as so l id c i r c l e s . The IMP-3

(1965-6) averages ( the so l id c i rc les i n Figure 1) are shown for comparison

as t r iangles .

Similar s ca t t e rp lo t showing the 3-hour IMP-1 (1963-4) data

Figure 3.

planetary f i e l d magnitude.

Scat terplot of the l i nea r geomagnetic index % with i n t e r -

The l i ne i s described by 5 = (1.5 f 0 . 1 ) B + 0.7

2 0.5.

Figure 4.

magnetic f ie ld . and the e c l i p t i c .

Scat terplot of I$, with 8 , the angle between the interplanetary

Figure 5.

planetary magnetic f i e l d .

Scat terplot of $ with the north-south component of t he in t e r -

Scat terplot of K with the radial component of the interplanetmy P Figure 6.

mwnetic f i e l d .

Figure 7.

plarietary magnetic f i e l d .

Scat terplot of 5 with the azimuthal component of the in t e r -

14.

Figure 8.

magnetic f i e l d component i n the e c l i p t i c plane.

Scatterplot of %-with the direct ion of the interplanetary

Average value of f o r the away sectors and the toward YP Figure 9.

sectors within each Bartels solar rotat ion. Typical probable errors are

shown including an estimate of the e f f ec t of the conservation property

of the data.

Figure 10.

and interplanetary f i e l d magnitude.

and the north-south angle 8 of the f i e l d .

Top curve crosscorrelation as a function of time l a g of Kp

Bottom curve crosscorrelation of Kp

Figure 11.

north-south field direct ion angle 8 , and of Icp.

Autocorrelations of interplanetary magnetic f i e l d magnitude,

. . . .

,.

:

* t ..

l-44 .* * . .

. . . .. * .

* * . * . . e . . . . _

e . . : . . * .: * . * * . . . . -. . ..' - . . . . . ..

. * . . *

.. . *

* - . . .. .

. . . * . . . . . .

..

. . . . : .' .

. . .. * -

1 . : .

0

0 0

0

0 0

0 0

0

0

0

0

0

0

0

0 0

0

0

0

0

0

0

0 * 0 0

0 0

0 0

0

O 0 0 0

0 0 0

0 0 0 0

O O

0 0 0

0 O O O

0 0 o o 0 O 0" ,"O"

0 0 0 0 0 0

0 0 0

0 0

0

0 0

0 0

0

0

o o

0

0

O 0 P o

0 O , " 0

0

0

0 0

O O

0 0 0

0

u)

1 r 1

. .

. .

.. . .

. . . * . . . . .

. .

* . . . . . . . . . . . . . .

. * . . . . . . . i , ' :

. . - . . 3 . . .

. . . .

0 0

\

. .

. . . . . .

*. . . . . +a+. . . . * . . . . . . 0 .

. . . :*. ;*. . . .' . . : .. . * * . . .. . . . . .. .

. . . *

* . . f

. . . . . . *. . .

- .

0 0.

0 9

0 m

T 0: 0 Z

. . .. . . . .: . .

. . . . . . . . .

. . . . . . ..

. .

Y

0 c u)

. .

. . . .

. .

. . * ..

. .

. .

. .

. . . . . . . . . . .

a . * . . I ; . . . . . . . . . . . . .

, e - . *.

. . . . . . * . . * . 1 . 1 . . . . . . . . . . . . . . . . . . . '.: -. . . . .

......... ..'.*'. . . . . - .(.. . .k. :*: ;.

. . . . . . . * . . . . . . .

. . .' . - ..... . . * . . . . .. . . . . . . . . . ;.a . . . . . .. . . . . . . .. . . . . , . . ..... . . . . . . . . . . . . . . . . . . . " .

. * . . . . . . . . . . . . . .... . . . . , .. , . . . . , . . . . . . . . :. * . . . . . . . . . . . . . . . . . ' .% . ** . * . *. . . . . . * * . . :

. e . . . e.. .. 9 ....... *. .* *'. .i :* . . . . . . . * .

. -- ..- . , ..

. . ,I. . . ;. ... . .* \ . ' . . . .

z . - * * .. * .

. . . . . . . . . . . . . . 0 . : . . . . . . . .. . . . . . . . .

. . . . . . .. . . . . . . . . . . . I . * " .:. .

, , . I ... . \ . . . . . . . . . . . . . . I . . . . . . . . * . * . a " * . .

. . * .. * . . . . . .

* * . . * . .

. . . . . . . . . . . . - . . :. . . . . * . . . . . . . . * . ,

* * . . , * * .

u) 0 0 c

0 - 0 u) 0 0 0 0 0 a h 9 u) * c ) c y cy c

I I N

. .

. . . . . . . . . . . . . . ..:&

... . . . . . . . .

. . .

. . . . .. *

. . . . . . . . . . . *

I

.. . . . .

. . 0 . .

I

c

Do

t

0

* I

a I

cy c

9 u) * Lri P

c) cy c 01

s m

n 0

v) 0 v) 0 0 0 0 0 0 0 - 0

a h 9 v) * m a cy c c

I 0 . .

. . .. . .

. *

. . . . . . . . . I :

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

,. - . . . . . . . - : , . . . . . . . . .

.' . . . . .

. . . . 1 . . . . . .

.. *. . . . - .

.... . * * .

. . . . . . . " . .' . . : .. . . . ... . . . . . . . 4 .

. .

. .

: :. - .. '

. . . . ..

... 1.. !-- .. . . .

. . . . ..

. . . . . . . . . . . . . . . . *.: . . . . . - .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 :.* : . . . .

. .

..

. .

. . . . . . . . . . I . . .

. . . . ... . e

. . : .. : . . . . . . . .

. . . *

- .' .

. . . . . . . . . . . . . . . . ' >.

. .

. . . . . . . - . .

. . 0 . . . . . . . . . .

. . .

. . - . . . .

. .

-

-

. . . .

9 u) 9

x P

cy ~

0 c

.

0 0 0 0 ci 7

.

>-

c

I 0 c + I I I e c 0 c + I

3 a n i i ~ ~ w ai314 aNv dl

:NOIlV13tl?IO3-SSOtl3

9 7

cy c

00

*

0

T I

00 I

cy c

I

9 c

I

AUTO-CORRELATION:

FIELD MAGNITUDE + 0 d

I -.I

e-

c I

1. OSlGlNATlN G ACTIVITY (Corporate atathorl

Space Sciences Laboratory I . 2.. R E P O R T S E C U R I T Y C LASSIFICATION

mcLAssIF1ED

UNCLASSIFIED

6. REPORT DATE 7.. T O T A L NO. O F P A G E S

March 28, 1967 25

~~ ~~

Security Classification DOCUMENT Ci?.::i”i?OL DATA - R&D

7 b . NO. O F R E F S

11 - 0.3. CONTRACT O H G R A N T NO.

Nom 3656(26)

University of California Berkeley, California 94720

9.. O R I G I N A T O R ’ S R C P O R T NUMSEF1(S)

Z b G R O U P

c Sb. oTnER R E P O R T NO(S? (Any othsrn-Toers chat may be asalpled

&la mport)

3 . REPORT T I T L E

11. SUPPLEMENTARY NOTES

-

RESFONSE OF THE GZOlUGIVETIC ACTIVITY INDEX 5 TO THE I l f f E R ~ A R Y MAGNETIC FIELD

Technical Report 4 DESCRIPTIVE NOTES (Typa of report and Inclusive dates)

5. AUTHOR(S) (Last namo. l i n t name, InltlaI)

12 SPOHSORING M I L I T A R Y ACTIV ITY

Huclear Physics Eranch Office of Naval Research Washington, D. C. 20360

Schatten, Kenneth H. and Wilcox, John M.

b. P R O J C C T NO.

NR 021 101 E.

Series No. 8, Issue No. 22 I d. I --

10 A V A IL ABILITY/LIMITATION NOTICES

Qualified requesters may obtain copies of t h i s report from DDC.

rotat ions i n the winter of 1963-4, indicating a s t a b i l i t y i n the response of geoQag-

ne t ic ac t iv i ty during these years near solar ae t tv i ty minimum. The 1arger.data

sample i n the present investigation reduces the probable error and delineates some ! ‘ in te res t ing resul ts .

, interplanetary f i e l d and the ec l ip t ic changes from south t o north.

/ t e n t with the reconnection of interplanetary and geomagnetic f ield l ines as suggeste

The average value of Kp decreases as the angle between the ,

This is consis-

by Dungey.

the index a i s =re l inear than , as might be expected. The re lat ion cau be

described by ap = (1.5 f 0.1) B + 0.7 f 0.5.

As a function of interplanetary f i e l d magnitude B, the average value of

‘b - P In the time in te rva l covered by these

I

WUSSIFIED Security Classification

UNCLASSIFIED Security Classification

K E Y WORDS L

Interplanetary magnetic field

Geomagnetic activity

Reconnection of magnetic field lines

- -

13. Abstract--cont'd.

LIC - R O L E

A W T

LII

R O L E

B

W T

obrenations the average value of 5 is consistently higher in sectors with interplane tary field directed away from the sun than in sectors with field directed toward the

Sun.

, r

I