Development of a plasmapause model derived from Van-Allen-Probe data and IMAGE RPI data via automatic detection

Abstract

The outer boundary of the plasmasphere, the plasmapause, is characterised by a sharp electron density gradient which changes under varying space weather conditions. With NEPPM (Neustrelitz ESOC Plasmapause Model), we introduce a new model of the plasmapause location Lpp based on electron density measurements made by the Van Allen probes from 2012 to 2016 and the IMAGE satellite from 2000 to 2005 that were automatically processed, yielding an improved performance for plasmapause detection. A 2D model provides a simple elliptical approach in the equatorial plane determined by the semi-major axis, the eccentricity, and the orientation angle. The Lpp varies as a function of Dst index and magnetic local time (MLT), resulting in a tighter fit compared to the GCPM (Global Core Plasma Model). The distinctive bulge in the evening hours follows the level of solar activity. By extending the ellipse fitting from the equatorial plane to a 3D approach, the NEPPM also allows non-dipole B vectors, providing 3D positions on the plasmapause torus for given latitude, longitude, epoch and Dst.