Meeting abstract

AGU Fall Meeting, San Francisco, 6-10 December 1998

Abstract:
The German Equator-S satellite observed, between December 1997 and March 1998, a large number (more than 100) magnetopause crossings in the low-latitude morning sector of the magnetosphere. The apogee of the spacecraft at 67,000 km allowed the observation of magnetopause crossings for medium to high pressure solar wind conditions. We review briefly the magnetopause locations observed by Equator-S and relate them to solar wind and geomagnetic conditions, as well as to geomagnetic field models. Close to several of the crossings, intense mirror-mode structures were observed. The orbit of Equator-S was particularly advantageous for such observations as it remained at a nearly constant radial distance for significant periods near apogee. Spectral analysis of the mirror-mode structures shows a characteristic shape of a well defined shoulder at about 0.05 Hz. The main features of the spectrum appear to be stable, despite significant changes in the temporal distribution and shape of the structures. We discuss the occurrence and characteristics of the observed mirror-mode episodes in relationship with the location and nature of the magnetopause crossings associated with them.