Universal time control of the parameters of the electron temperature enhancement zone in the winter subauroral ionosphere

Abstract

Comparison of the numerical simulation results with experimental data obtained aboard the CHAMP spacecraft has shown that in the eastern longitudes during the local winter period the parameters of electron temperature (Te) enhancement zone in the subauroral ionosphere undergo significant changes depending on the universal time (UT control) as a result of the formation of the shadow region, almost devoid of direct sources of ionization due to the displacement of the geographic and geomagnetic poles. Thus, in the time interval of 04–07 UT in the northern hemisphere and 16–19 UT in the southern hemisphere, a zone of increase of Te in the region of main ionospheric trough can have the greatest length and square, and take a ring-shaped configuration; in the time interval of 16–19 UT in the northern hemisphere and 04–07 UT in the southern hemisphere the length and square of Te enhancement zone decrease, and its configuration becomes crescent. The study has been carried out under the assumption that the main reason for the Te enhancement is the ring current that causes a downward heat flow from the plasmasphere.