Tracing Geomagnetic Conjugate Points by means of Extremely

Similar Interhemispheric Auroras

N. Sato (1), A. Kadokura (1), Y. Ebihara (1) ,H. Deguchi (1), and T. Saemundsson (2)

(1) National Institute of Polar Research, Tokyo, Japan (nsato@nipr.ac.jp)

(2) Science Institute, University of Iceland, Iceland

National Institute of Polar Research (NIPR)

IAGA 2005

Auroral Conjugate Observation at Syowa and IcelandVisualization of the conjugate foot prints of the geomagnetic field lines

Mapping of Northern/Southern hemispheres with geomagnetic coordinate

Conjugate point of Syowa Station (IGRF model)

Station

Glat (deg)

Glon (deg)

Inv.lat

(deg)

Mlon (deg

)

MLT (hr)

at 0.0 UT

L valu

e

D (deg)

I (deg)

B (nT)

Tjornes

66.20 -17.12 66.41 71.26 23.46 6.25 -16.21 76.57 52321

Syowa -69.00 39.58 66.27 71.75 23.49 6.17 -48.68 -63.61 43178

Comparison of geomagnetic parameters (Epoch: 23:20:00 UT, 26 Sep, 2003)

All-Sky Image and Geomagnetic mesh

at 120 km altitudeTJORNES SYOWA

at 23:23:00 UT on Sep. 26, 2003Magnetic zenith

Projection on Geomagnetic planeat 120 km altitude

TJORNES SYOWA

at 23:23:00 UT on Sep. 26, 2003 (elevation > 10 ﾟ )

Abstract of the Syowa-Iceland Auroral Conjugate Observation, so far

• Starting from 1984 (20 years anniversary ）• Executed every year in the equinox season,

mainly in September, for about two weeks• Simultaneous darkness for about 4 hours• Only 2～ 3 nights of simultaneous observation

in one season, mainly due to weather condition• Good conjugate event is rare

★September 26, 2003 event : 　 The best conjugate event in the 20 year

history

SYOWA IcelandFluxgate magnetometer ○

Induction magnetometer ○

Riometer ○

VLF receiver ○

Imaging Riometer ○

All-sky TV camera ○ (only equinox)

All-sky monochromatic Imager ○ (from 2005)

Meridian Scanning Photometer

Fabry-Perot ImagerSuperDARN radar ○

MF-radar

Ionospheric vertical sounder

VHF Doppler radar

Instruments at conjugate stations

Iceland ～ UK SAMNET magnetic meridian

September 26, 2003 event

HAD

YOR

UPS

NUR

HAD

YOR

UPS

NUR

H D

SAMNET data Pi2 onset : 23:18 UTOnset occurred at westward of Iceland

meridian

TJR

TJR

TJR

SYW

SYW

SYW

MN

S

W E

N

MS

W E

September 26, 2003 event all-sky TV data (23:19:30 ～ 23:23:50 UT, 10 sec interval)

TJR

TJR

TJR

SYW

SYW

SYW

September 26, 2003 event all-sky TV data (23:24:00 ～ 23:28:20 UT, 10 sec interval)

TJR

TJR

TJR

SYW

SYW

SYW

September 26, 2003 event all-sky TV data (23:28:30 ～ 23:32:50 UT, 10 sec interval)

September 26, 2003 event Total Intensity & E-W Keogram

TIME (UT)

Finding one-to-one correspondenceTracing temporal variation of conjugate location

Tracing temporal variation of conjugate location of Syowa

IMAGE/FUV WIC and POLAR VIS Earth Camera

Longitudinal displacement depending on the clock angle

Satellite Observation

Østgaard et al. (JGR, 2004)

-6

-4

-2

0

2

4 Sep.26, 2003

BxGSM(nT)

-4

-2

0

2

4

ByGSM(nT)

-4

-2

0

2

4BzGSM(nT)

0

90

180

270

360

21.0 21.5 22.0 22.5 23.0 23.5 24.0CLOCK ANGLE(deg)

TIME (UT)

(X, Y, Z)gsm = (29.0 ～ 28.6, 11.1 ～ 12.5, 2.4 ～ 1.9) ReACE Vsw ～ 500 km/s

IMF dataGeotail

Østgaard et al. (JGR, 2004)

T – 8.3 minfor X= -10

Re

Magnetic variation at Syowa and Tjornes

TJR

SYW

TJR

SYW

H（ｎT)

TJR

SYW

D（ｎT)

Z（ｎT)

26-27 September, 2003

Equivalent current & Ionospheric potential

H

D

Z

equivalent current

&ionospheric p

otentialB

＋TJRSYW

TJR

SYW

j|| N

j|| S

If BN < BS then NP could be located eastward of SP

NP

SP

North-South asymmetry of magnetospheric configuration ?

dB

dB

BN

BS

Why BN < BS ?

IMF Bx effect ? (Bx < 0 in this case)

IMF Bx

SummarySummary The September 26, 2003 event is the best one in

the 20 year history of the Syowa-Iceland conjugate auroral observation.

Extremely similar auroral activities were observed for more than 1 hour.

During the observation, the conjugate point moved about 200 km in longitude and about 50 km in latitude.

This movement cannot be explained only by the By or clock angle effect of the IMF.

North-south asymmetry of magnetospheric configuration could be a cause of the movement.

Vsw(km/s)

B (nT)

By(nT)

Bz(nT)

ASY-D(nT)

ASY-H(nT)

SYM-H(nT)

ACE

Overview of the solar – geomagnetic condition

14-29 September, 2003

September 26, 2003 event All-sky TV data (23:50:00 ～ 23:55:50 UT, 10 sec

interval)TJORNES

SYOWA

MH

ML

W E