Seminars

Lecturer: Dr Masatoshi Yamauchi
Date: 2005-10-27 10:00
Place: Aniara

Sub-keV ring current ions as the tracer of substorms

Dynamics of the structured dispersive sub-keV trapped ions inside the ring current region, so called wedge-like dispersions structure, were statistically studied using Viking satellite data. Probabilities with/without these signatures at various local times in dayside are obtained in terms of different time lags from the substorm activity monitored by the AE index. The structure appears in the early morning sector within a few hours after a substorm, and it slowly propagates eastward while decaying with a time scale of several hours. The result qualitatively confirmed the previous model that the wedge-like dispersions are the signatures of past substorm injections that slowly move mainly by the ExB eastward drift from nightside. However, the drift speed is twice or three times faster than the model prediction, and some drift can reach even to the evening sector. We also detected the evacuating effect starting right after the substorm (or storm) onset. The electric field imposed in the dayside magnetosphere seems to remove the remainder of trapped ions.

Created 2005-10-24 14:19:11 by Rick McGregor
Last changed 2005-10-24 14:19:11 by Rick McGregor