Plasmasphere electron temperature model based on Akebono data Original Research Article

Average electron temperature (Te) distribution in altitude range 1000–10,000 km and in geomagnetic latitude range ± 70° are used to construct a simple analytical model of Te. Te distribution is considered constant during daytime (9–16 h) and nighttime (22–04 h) local time sectors. Transition between the constant thermal states is described by cubic splines. The vertical Te profiles at fixed geomagnetic latitudes are approximated by second order polynomials and then the three constants of these polynomials are approximated by another set of analytical expressions, being explicit functions of altitude, geomagnetic latitude and local time. No seasonal variation or hemispheric asymmetry is considered in the model. The average Te distributions at L shells greater than three were reconstructed, in order to avoid the unrealistically high temperatures measured in the regions with low plasma density. For this purpose, Te distributions above 3000 km along the L shells were calculated, taking the gradients obtained at L=2 (0.3 K/km during the day and 0.1 K/km during the night), reduced with latitudes as 1/(L−1). The accuracy and limitations of the model are discussed.