Investigating seasonal features of electron temperature enhancement regions in the subauroral ionosphere

The electron temperature enhancement is known to occur in the main ionospheric trough during geomagnetic disturbances. In this paper, we study features of the formation of the electron temperature ( Т е) enhancement in the subauroral ionosphere by comparing results of the numerical simulation with measurements of T e onboard the CHAMP satellite under moderate geomagnetic activity conditions. It is shown that depending on the terminator position and universal time (UT), the location of the enhanced T e regions in the subauroral ionosphere varies in different seasons. So, in winter ring-shaped and sickle-shaped regions can be formed, whereas during the equinox and summer periods sickle-shaped regions of different lengths and clarity are generally observed.