Two-phase storm profile of global electron content in the ionosphere and plasmasphere of the Earth

摘要

[1] The global electron content (GEC) derivation is initiated by summing up the total electron content of each cell of Global Positioning System GPS-TEC global map multiplied by the cell area. Algorithm of GEC calculation is improved in the present paper using the electron density varying with height through the total volume of a spherical layer in near-Earth space up to 20,200 km (GPS orbit) reconstructed from TEC with the International Reference Ionosphere model extended to the Plasmasphere (IRI-Plas). An analytical model is first derived for two-phase typical GEC storm profile by a common epoch analysis of 10 storms during 2001-2011 with the starting time put at the origin of the negative phase of GEC departure from the quiet reference (5 day median). It is found that GEC depletion occurs synchronously with decrease of the solar wind velocity and the outset of recovery of the magnetospheric ring current (the equatorial Dst index) and the auroral electrojet (AE index). Thus, the GEC is an indicator of the plasma injection in the ionosphere and plasmasphere with the solar wind energy inducing the positive phase of GEC storm during 24 h with electron number increased by 10-20% followed by a negative phase with GEC decrease by 10-20% during 40 h of a plasma release (ejection) into the magnetosphere tail beyond the three Earth radii (GPS orbit).