engleski

MLT dependence in the relationship between plasmapause, solar wind and geomagnetic activity based on CRRES: 1990-1991

Using the database of CRRES in situ observations of the plasmapause crossings, we develop linear and more complex plasmapause (Lpp) models parametrized by (a) solar wind coupling functions V (solar wind velocity), BV (related to the solar wind electric field, where B is the magnitude of the interplanetary magnetic field IMF), and dΦmp/dt (which combines different physical processes responsible for the magnetospheric activity), and (b) geomagnetic activity indices Dst, Ap and AE. The complex models are built by including a first harmonic in MLT. As in many previous studies, all our results show that the plasmapause is more earthward during geomagnetically active periods. Our approach based on the cross correlation analyses provide a similar Lpp shape as found by O'Brien and Moldwin [2003], but additionally yield the information of the delays in the MLT response of the plasmapause. This study suggests that convective instabilities that occurred first in the postmidnight MLT sector are transported to other MLT sectors via interchange motion. We observed that any change quickly propagate across dawn to noon, and then at lower rate toward midnight. The results based on CRRES observations confirm those obtained with CLUSTER [Verbanac et al., 2015], but indicates additionally that the instability propagates much faster during maximum than around minimum of solar activity. This study contributes to determine the MLT dependence of the plasmapause.

Plasmapause ; solar wind ; geomagnetic activity ; CRESS Satellite

Verbanac Giuliana je autor za korespondenciju (corresponding author).