Plasmapause evolution during prolonged conditions of quiet geomagnetic activity 

Ljiljana Ivanković - University of Applied Sciences Velika Gorica, Croatia; Mario Bandić - Astronimical Observatory Zagreb, Croatia; Giuliana Verbanac - Department of Geophysics, Faculty of science, University of Zagreb, Croatia; Viviane Pierrard - Royal Belgian Institute for Space Aeronomy (Space Physics and STCE), Belgium 

Session: QV - Earth's Magnetosphere and Radiation Belts

Abstract

We observe changes in plasmapause position during the time period from 21 August to 1 September 2008. During this time geomagnetic activity was low, indicated by low values of geomagnetic index Kp (Kp<2). Plasmapause positions were identified from electron density profiles measured by THEMIS satellites. Each profile shows dependence of electron density on shell parameter L, and six ones were used in this analysis. In every profile, satellite crosses plasmapause around MLT=15. For each profile, we determined plasmasphere boundary layer (PBL) by identifying two boundaries, inner and outer. Then, we examined velocities of the boundaries from a graph showing PBL position against
time. We estimated that PBL for all profiles is less than 1 L wide, with the mean width 0.5L. Also, we found that PBL moves outward and its velocity decreases as geomagnetic activity remains low.