Seminars

Lecturer: Audrey Schillings (IRF)
Date: 2016-05-19 10:00
Place: Aniara

Ion escape during extreme events - Cluster observations

Audrey Schillings
Swedish Institute of Space Physics

Abstract
Cluster is a constellation of four satellites flying in tetrahedral formation around Earth in a polar elliptical orbit. Using Cluster data, four extreme events of ion outflow were identified between 2001 and 2004. For each event, the oxygen and hydrogen ions fluxes (O+ and H+) are analyzed. After the case studies of individual events, a statistical study of ion escape is realized, which contains many years of data including the extreme events. The main objectives of this study are to determine the order of magnitude for the ion escape during extreme events and to define the area that contributes to the escape compared to the quiet times.
Currently, two extreme events were studied, the first one occurred in March 2001 and the second one, the Halloween event, occurred in late October 2003. The durations of the extreme events were determined from examination of energy spectrograms and pitch-angle spectrograms. Oxygen and hydrogen ion fluxes as well as the plasma beta were studied along the satellite trajectory. The plasma beta and the spatial region together determine the magnetospheric region where the observations were made. Finally, the start of the statistical study seems to indicate a two order of magnitude increase for the oxygen ions flux compared to fluxes observed during quiet times.


Created 2015-11-06 10:19:25 by Mats Holmström
Last changed 2016-05-12 09:33:59 by Mats Holmström