Development of substorm bulges

during storms of different

interplanetary origins

 I.V. Despirak1, A.A. Lubchich1, V. Guineva2

 1. Polar Geophysical Institute, Apatity, Russia

2. Solar-Terrestrial Influences Laboratory,

Stara Zagora, Bulgaria

IntroductionThe storms are mainly generated by different types of solar

wind:

ICME including Sheath and body of ICME (MC) and CIR

(Vieira et al. (2004); Huttunen and Koskinen (2004);

Yermolaev et al.,(2005); Yermolaev and Yermolaev (2006))There are differences between storms generated by Sheath, MC and

CIR (in intensity, recovery phase duration, etc.)

(Borovsky and Denton, 2006; Denton et al., 2006; Pulkkinen et al, 2007).

Motivation of studyTo investigate the distinctions in the development of

substorms occurring during geomagnetic storms

connected with the MC, Sheath and CIR.

We use the optical data of substorm development from the Polar satellite which are compared with interplanetary medium parameters measured by the Wind satellite.

L lo n g

2 1 :5 7 :2 5 U T

0

6

1 2

1 88 0

7 06 0

L mL la t

S

2 1 :3 2 :5 3 U T

0

6

1 2

1 88 0

7 06 0

L o

Lo- onset latitude Lm- maximum latitude

Llat, Llong- latitudinal and longitudinal

size of the bulge

The auroral substorm development is studied here on the basis of the

Polar UVI data in LBHL band (1600-1800 Å).

Examples of the Sheath, MC and CIR observations from WIND spacecraft data

 

0

10 000 00

20 00 00 0

3 00 00 00

T, K

0

10

2 0

30

N, c

m-3

-2 0

0

20

40

6 0

Ey, m

V/m

-1 20 0

-10 00

-8 00

-60 0

Vx, k

m/s

-6 0

-30

0

30

6 0

BT

, Bz ,

nT

00 :00 12 :00 24 :00 36 :00 48 :00

15 .07 .20 00 16 .07 .2 00 0

SS h . M C

0

1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0

T, K

1 0

2 0

3 0

4 0

N, c

m-3

-2 0

-1 0

0

1 0

2 0

Ey, m

V/m

-8 0 0

-6 0 0

-4 0 0V

x, km

/s

-3 0

-1 5

0

1 5

3 0

4 5

BT

, Bz ,

nT

1 2 :0 0 2 4 :0 0 3 6 :0 0 4 8 :0 0

1 7 .0 9 .2 00 0 18 .0 9 .2 0 00

S h . M CS

0

2 5 00 0 0

5 0 0 0 0 0

7 5 00 0 0

T, K

1 0

2 0

N, c

m-3

-5

0

5

Ey, m

V/m

-6 0 0

-4 0 0

Vx, k

m/s

-1 0

0

1 0

BT

, Bz ,

nT

12 :0 0 2 4 :00 3 6 :0 0 4 8 :0 0 6 0 :0 0

2 8 .0 2 .1 9 9 7 0 1 .0 3 .1 9 9 772 :0 0 8 4 :0 0

C IR R SS

CIR-generated magnetic storm:

0 12 24 36 48 60 72hour

-100

-75

-50

-25

0

25

50

75

100

Dst

RS RSCIR RS

during CIR of 28 February 1997  

Onset latitude 55.3º ;

Maximal latitude 82.3 º;

The ratio between longitudinal and

latitudinal sizes (Ld/LF) 8.8

substorm occurred under high values of

solar wind parameters

(VX ~ - 705 km/s , BZ ~ - 12.5 nT) and

during the storm main phase

(Dst ~ - 67).

0 8 1 6 2 4 3 2 4 0 4 8h ou r

-300

-200

-100

0

100

200

300

Dst

1 507 00 1607 00MC

Sheath

Sheath or MC – generated magnetic storm:

during MC of 15 July 2000

Onset latitude 50.5º ;

Maximal latitude 68.7 º;

The ratio between longitudinal and latitudinal sizes (Ld/LF) 17.7

substorm development under extremely

high values of solar wind parameters

(VX ~ - 1022 km/s, BZ ~ - 35 nT) and

the auroral bulge dynamics during

magnetic storm main phase (Dst ~ - 198).

Event 21-22.10.2001: (Pulkkinen et al., 2006)

0 8 16 24 32 40 48 56 64 72h ou r

-200

-150

-100

-50

0

50

100

150

200

Dst

2 1 1 0 0 1 2 2 10 0 1

Sheath

1) 2) 3)1) 2) 3)

2)

3)

Event 21-22.10.2001: (Pulkkinen et al., 2006) 1)

5 10 1 5 20 25L d /L f

0

5

1 0

1 5

2 0

2 5

3 0

Íîì

åð ñ

ëó÷

àÿ

0 5 1 0 1 5 2 0 2 5L d /L f

0

5

1 0

1 5

2 0

2 5

3 0

Íîì

åð ñ

ëó÷

àÿ

MC: CIR:

Ratio of longitudinal to latitudinal dimension of the auroral bulge:

Median and quartile values of the latitudinal and longitudinal sizes

for the substorms

during MCs and RS’s

for CIR- and Sheath- associated

substorms

Conclusion

The auroral bulge “geometry” differs for substorms occurring during storms generated by different interplanetary origins.

Especially during MC- storms the auroral bulge is confined in latitude and extended in longitude. We relate this to MC-like configuration of the near-Earth magnetotail, which is very stretched in wide range of MLT.