Universal Time Variation of ISIS-2 6300Å Auroral Observations During the Quiet Period Dec. 9-13, 1975
1983 年 35 巻 4 号 p. 87-102
詳細
1983 年 35 巻 4 号 p. 87-102
Data obtained by the ISIS-2 6, 300Å photometer were analysed for a relatively undisturbed five day winter period. Auroral emission intensity data were available for 50 out of 60 possible passes. A clear Universal Time pattern for auroral oval intensity repeated each day. The initial analysis was simplified by fitting the maximum intensity oval to a circle, which was 15 latitude degrees in radius most of the time, and offset from the geomagnetic axis by 4 to 5° away from the direction of the sun.
The daily pattern showed a maximum intensity on the dayside in the morning hours UT. It split into two peaks as the day progressed and migrated around the auroral circle to about 9 to 21h LGT at about 18-20UT, gradually becoming indistinct. The phenomenon was confirmed by more detailed examination of all available data. Although the UT variation is reasonable to expect, the intensity split and migration are more difficult to explain.
