Experimental Study of the Plasmasphere Boundary Layer Using MAGION 5 Data

Abstract

The in situ cold plasma measurements onboard MAGION 5 were carried out with very good time resolution, and this permitted to analyze thin plasmasphere boundary layer (PBL) near the plasmapause. In this layer the plasma density N is decreasing exponentially with L: N~exp((LPP − L)/WB), where WB corresponds to the characteristic width of the PBL, the distance in L within which the density varies by a factor of e, and LPP is the position of the plasmapause. The density in the boundary layer is inversely proportional to the volume of the unit magnetic flux tube, whereas its width is proportional to the volume of magnetic flux tube. The characteristic width of the PBL linearly depends on the time elapsed since the most recent maximum value of KP. Empirical relation for the dependence of the PBL width on most recent maximum value of KP and on the lapse time between this maximum and the plasmapause observations is proposed.

Improving Predictions of the 3D Dynamic Model of the Plasmasphere

“…But the plasmapause is not always a sharp frontier. A thin plasmasphere boundary layer (PBL), where the plasma density starts to decrease exponentially with L below the plasmapause limit allows taking into account the width of the PBL, which is observed to linearly depend on the time elapsed since the most recent maximum value of Kp (Kotova et al, 2018). This happens especially during refilling periods after geomagnetic storms, as taken indeed into account by the model (see Pierrard and Stegen, 2008).…”

The Role of Plasmasphere in the Formation of Electron Heat Fluxes

“…Besides, these results indicate excellent comparison of selected plasmaspheric model by Pierrard, Botek, and Darrouzet (2021) with the thermal density of RBSP observations. The proper selection of plasmaspheric temperatures in 3D model (Pierrard & Voiculescu, 2011) was also an important element contributed to successful comparison of this model with different kinds of plasmaspheric observations (Kotova et al., 2018). The BSPM model was recently used to compare the positions of the plasmapause with the boundaries of the auroral oval and the radiation belts (Pierrard, Botek, Ripoll, et al., 2021), and in the past with suboval auroral spots (Yahnin et al., 2013) and spatiotemporal structures of poloidal Alfvén waves detected by Cluster adjacent to the dayside plasmapause (Schäfer et al., 2008).…”