,5 ,3,

8.- The disturbed solar wind

Fig, land 2 show that the solar wind flow is not as steady and structureless as assumed in almost all theoretical models.

- w from 300 kmlsec to 700 km/sec

-3 -3

from 1 cm to 20 cm , etc.

- n

Different types of variations are observed: High speed plasma streams, are ed interpl Shock waves, discontinuities ...

(F , 3 , 4)

w rises steeply and decreases more slowly in 3-5 days n increases to 15-20 cm -3 and near 1

increases from 4 l04K to 40 l04K

,

(T

IT

1 )

II p

T

IT

a. p

n

In

IX p

Iv -v

I

IX p

F , 5 shows that high speed streams are associated with the structure,

ic sector

- Fig. 6 shows how a high speed stream overtakes the slow solar wind plasma and illustrates the possible shock formation at the front and the rarefaction zone behind the stream,

High s streams seem to or te in lived coronal magnetic field structure above with a predominant ic ity which is the same as in the of the Sun.

- Some numerical time 1 models have been crudely

account for the observations at 1 AU,

-91-

- The lack of any apparent relationship between the 11 year solar cycle and the average solar wind properties indicates that high speed streams are probably not associated with active centers on the surface of the Sun.

Flare produced interplanetary shock waves

Fig. 7 shows the solar wind changes associated with a solar flare produced interplanetary shock wave.

Enriched helium plasma shell is ejected out of the sun with a high speed. It compresses the ambient solar wind. A shock front is produced at the leading edge with magnetic field distorsion (Fig. 8).

- w, nand T increase after the shock which propagates in the interplanetary medium with a speed of 500 km/sec (Ma~h number

=

(from

1%

- Not all observed shock waves can be attributed to flares !

- Some theoretical time dependent models have been proposed to describe "piston driven" and "blast" shock waves in the solar wind.

- These very fast interplanetary plasma stream are sometimes associated with intense H emission at the surface of the Sun.

0:

Directional discontinuities

- Fig. 9 illustrates the two possible types of directional discontinuities in the magnetic field distribution (rotational discontinuity with

B.; F

--

tangential discontinuity with B.n = 0)

- The high time resolution magnetic field measurements of IMPI (Explorer 34) (one measurement of Beach 0.08 sec) show the detailed structure of the change of B inside these discontinuity layers convected pass the spacecraft with the solar wind speed.

Fig. 10 illustrates the large change observed in the B and magnetic field x

component in a period of 4 seconds. The axis is the minimum variance direction determined by numerical analysis.

- 128 events of this have been examined. In all cases considered we found that B was almost equal to zero : this indicates that these directional

z

are actually ial discontinuities.

- The minimum variance directions (Fig. 11) cluster mainly in a direction per-

pendicular to the spiral direction (Le. the surface of discontinuity is leI to s 1 direction) and leI to the ecl ic plane.

- The total angular change of the magnetic field range fram zero to 150⁰ as can be seen in Fig. 12.

The thickness distribution usually in seconds of time is illustrated in Fig. 13.

- Using the simultaneous solar wind velocity (~) mrasurements of IMPI, and the

...

between wand OZ, (the minimum variance direction) the thickness in kilometers could be determined for each of the 128 events. . 14 illustrates the thickness distribution in kilometers for this sample.

The thickness distribution was also calculated in average proton gyroradii (See Fig. 15). The thickness distribution is much better with the average gyroradius as unit of length instead of kID in Fig. 14). This is an indication that the gyroradius determines probably the intrins thickness of these current

- A kinetic model of these al discontinuities enabled us to show that the electric currents that maintain these are ic currents

undissipated along the boundary surface of field al plasma elements or ties convected by the solar wind. The theoretical thickness are found of the order of the 3-5 times the average proton gyroradius and are there- fore comparable with the observed thickness of discontinuities,

u

Q)

\J\

>-

-

u o

Q)

>

-93-

800 ~-- ---~.~~--,----,~

7

ao _

500 1.00

- 00 .

j Aug.27 S<-e-Pt'".I-"-- SePt5~Sept11 Seot.16 Sept. 21 800,' . ^{~- ~---} - ^~ . ..,. ^{r --~,-, --, --'-' ,--~,} -,,~~-r--'-=~~-

L Rotation 1768 700,

600

f~

500 )1'

J

I. 00

10

100

10

~ ~~ 'r:SC:-e-=CptC--:. 23"*"· ... ~--;~;f-e-~-';-t.~2~~-_-'-:_ 0::-c~~-;:-3~T.-~~ ^.. .J_.,-~g.-:c'-',t--::,,,,,.8~'=:.:~.L,_-:O"i,c"2t·r,l:O-3:-,r--,:~,-,--;0-:-C-:-t.';;,18o-"r""""---"-...J ¹⁰⁰

700 ^Rotation 1769 600

500 l.OO

10<") E

300~~~~,~~~~~~~~~~~~~~~~~~~~~

800 Oct19 _--r,...:..N-;:,(}J...:...,~4~~.--:-;.=;'--r-~-,-'-'-.;::..c;r-,..~_...--, 100 Rotation 1770

700 600

y,

500 J\,

~~~ (~~

~;:----'---'--c~:--'----'---~-;::--~-~'~~--'-~'---'

10

Nov16 Nov 21 Nov26 Decl Dec.6 Dec.l1

800 . ---. ·r .-~ ... - . - r r -,--, - , =,., ~, - - ' - - . - T - '--' -,--,--, ---r ----r~ ~ -r-r-- 100 Rotation 1771 1\

700

j \

600 MJiJ1J

~I \ 1 ~ ~ ~

500

I

r ^~ .

1.00

Fig_ 1. Three·hour averages or the solar wind rroton dcn,ity and Ilpw sreed observed by Mariner 2 in 1962 The time coordlnatc has bcen hroken into n-day solar rotation periods

10

--

~ o _a.

300

20

E 15-

<>

Z 10

1.4

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1.2

IMP 6

~ .\. ^/rI1M~

1\4j""'VL·\,\i---,'-'1-L.J-~~~~

:. (') 1 8 9 10 II 12 13

April Time (days)

Figure

:z

Up (km/secl

no/np

-95-

~o- -

"llf~- ~ ~~:;'

SHOCK

I SH<X..-: INIf~lnc[

500 I

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350 N< ~

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, ·1·· .. ^'110 ~ ~~"'i '..,,; #"-r";:' v,. . .1>..: :).'n .,.:..r- ----"I ----,

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(U p- Ua ) IUp I

(PERCENT) -10- I

1 I"., .... · ~ , I ,.~ f'~~ -, to .::,. I

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- 20^LJ-'I"'9-'-2"'Oo-'--=Z""I-"-=2""Z--'-Z::-:3'"" fO-^L' ""2~5-'--,2~6-"-'~L"7...J..~2'""B..L-.2'""9.J.1-::3~0-,,,-1 3~1-'--.I-1J ~-'sL'-':'~-'---'--8--"~9~

MARCH ₁₉₇₁ APRil

101"1<)

I IO-~

Fig. J(T0[l [lJnel) i'ru1011 hulk s[leet.! Jild tCllI[lcr;lIure. (Se~"lId [l"ncl)I'rtIIOIl dCllsil\. (111m] [lJllel) IlcliulIl 10 h)dro·

gen temperature ralio. (Fourth [lanel) Normalilcd bulk _'[leeti dilfercncc for the [lcriod March IX to /\pril 9, 1971.

Fig. t.;

IAU

o w-;-

wu

Q w ( / ) ( / )

~~ 00<:

...J LL

u ~

>--

f- (/) Z W o

Q

~

600

500

400 300

~ 105 Z ~ o

.

...

....

.

21 22 23 24 25 26 27

~ 104L-_~ _ _ -L _ _ l -__ ~ ____ -L--J--~

APR.21 22 23 24 25 26 27

TIME OF OBSERVATION

1\ nonlinear. transient. srherically·symmctric solar willJ disturh;tlllC at Vela J ohservations . , are shown for c(lmparison

'-' c

CJ)

'"

EO c Q '-'

.111 ,---,----,---, -- - - r - -. , - ---,--, ---,

0 0 0

A I'ield away rrom sun --- field loward slin

o I-Icld ilW,I)' + lield Iowa rd

::!()

~ -~---

0 ~

- 0 0

15 ⁰⁰

-

00

.

10

~~--~--~--~-~--_L--~--~~-----~

'() 2 3 4 5 6 7 ~

Position within ~n sectors (d;l)s)

TI(;UI<I' ,f

Actual cLuJ fOl' the variation of "::,/(/' (twenty-four-hour sum) with nosition in the (two-sevenths) sector.

Fig.

6

-97-

i'

o 500~

w-

t

we.,

e;w 400

(/) , ... :, ... "' ...

~ ~ , . - r

g"" 300 ... :.~ .. -.

u. l_ . . L I

0000 0600

OC14 1 OCT 5

'.'

... .:.r~ .

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

-

...

..

.:._..J,..~ .... ...-O_.-... ... _--"---'-_I

1200 1800 2400

ocr 5'

Fig.:;' The rroton density. now sreed. and kinetic energy nux density observed before and during the interplanetary shock wave of Oct. 5. 196~

FLARE SITE AT TIME OF I AU ARRIVAL OF SHOCK (2 TO :3 DAYS AFTER

FLARE)

f I~

t / ' ( /

I /

Fig. H.

A synortic view of narc-associatcd Sircam features.

Tangential discontinuity. B is parallel to the surface of the disconlin~~iIY, but its direction may change across the surface.

I I ! ^{I I I I}

I I I I I

I >< >-

l- ^I I

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ALFVEN SHOCK

R OTATIONAL DISCONTINUITY

B --.

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60~----~---~----~---~----~---~

50

40 -

o o

N 128

-

50° 22 .

X

()X

30°42

30 60 90 120 150 180

"

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X = ANGLE (B 1

B

I N DEGREES

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(f)

W t-

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x = T Hie KNESS INK M

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