High electron temperature associated with the prereversal enhancement in the equatorial ionosphere

Abstract

High electron temperature in the equatorial ionization anomaly region detected first by Kyokko satellite and later observed frequently by Hinotori satellite are found to be closely associated with the ionization crests of the anomaly. This phenomenon, called the equatorial electron temperature anomaly, is found to occur predominantly in the equinoctial months and to become enhanced with the increase in solar activity. It is mainly a nighttime phenomenon and shows maximum temperature enhancement at around 2100 LT. Using a theoretical model, a mechanism for its occurrence is presented. The mechanism is based on the plasma transport in the evening equatorial ionosphere resulting from the sunset electrodynamical processes.