National Institute of Polar Research
Upper Atomosphere and Space Research Laboratory, Tohoku University
Geophysics Research Laboratory, University of Tokyo
Institute of Research and Development, Tokai University
Faculty of Engineering, Tokai University
The EXOS-D satellite was launched on February 22,1989 into an elliptic orbit with a 75°inclination and with an initial perigee and apogee of about 275km and 10500km, respectively. Although the complete set of observations did not begin until the beginning of April, the fluxgate magnetometer was in operation during the great magnetic storm of March 13,1989,which has been one of the greatest storms this century. This preliminary report describes the characteristics of the field-aligned currents (FACs) observed by EXOS-D in the morning and evening sectors during this magnetic storm. The FAC system in the morning sector observed during the main phase spread greatly in invariant latitude (33°), its lowest latitude reaching as low as 50°. FAC events both in the main and recovery phases showed the following common features : (i) The presence of a pair of distinct FAC regions, an upward current on the poleward part and a downward current equatorward; (ii) the existence of a pair of FACs with narrow latitudinal width (1.5°) at the poleward edge of upward current in (i). In the evening sector the lower latitude boundary of the FACs began to move equatorward right after the SSC and eventually reached as low as 50°, but the higher latitude one did not immediately respond to the SSC. As the recovery the storm progressed, on the other hand, the higher latitude boundary of the FACs returned poleward more quickly than the lower latitude boundary.
EXOS-D 搭載磁力計で観測された 3 月 13 日大磁気嵐中の沿磁力線電流分布
SA0166928.pdf
(427.46KB)
