| 摘要(英) |
Abstract
The ROCSAT-1 satellite was launched into a circular orbit at about 600 km altitude with an inclination of 35 degrees. The onboard ionosphereic plasma and electrodynamic instrument (IPEI) takes in-situ measurements of ionospheric parameters. The ROCSAT-1 orbits cover the geographic latitude range between 35°N and 35°S (maximum magnetic latitude, about ±50°). The data used here include ionospheric ion density, temperature, ion drift velocity and ions composition measured by IPEI during the great magnetic storm on March 31 and April 1, 2001. These data are used to demonstrate the presence and the local time (LT) distribution of the ionosphere plasma density troughs whose equator-ward boundaries extended to the lower mid-latitude region during the heights of this storm. Furthermore, wave spectra of ion density, and the two cross-track velocity components at equatorward boundaries of troughs are analyzed to investigate the spatial scales of the irregularities and the associated processes. During this storm (DST is at the lowest –390 nT in 09:00 ~10:00 UT, kp > 7), the trough equatorward boundary were found at magnetic latitudes as low as -40° ~ -43°. In pre-midnight sector, the latitude of this boundary moved equator-ward as local time increasing. Inside the trough region, at latitudes which are higher than those of trough equatorward boundary, large westward ion drifts were detected (about 1000 m/s ~ 1600 m/s). In addition, significant disturbances in temperature and ion composition were observed inside the trough region. The poleward electric field observed in this region was increasing with increasing latitude in the pre-midnight sector. The results of spectral analysis indicate that there exist irregularity structures with spatial scale size from 100 m to 10 km, and electromagnetic wave signatures at the eguatorward boundary of the trough. |
| 參考文獻 |
參考文獻
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