Satellite model of foF2 in winter high-latitude ionosphere describing the trough structure

An empirical foF2 model was constructed for the winter high-latitude ionosphere taking into account the structure of the ionization trough. This model describes the trough position and its shape in terms of longitudinal-latitudinal variations in foF2 in geographic latitude intervals of 40–85°N and 40–85°S. The model is valid for November to February in the Northern hemisphere and May-August in the Southern hemisphere. The simulation describes quiet geomagnetic conditions (Kp from 0 to 3+ for all local time (LT) and universal time (UT) hours at any solar activity level in the interval F10.7 = 70–200 s.f.u. The model is based on the Cosmos-900, Interkosmos-19 and CHAMP satellite data. The radio occultation observation data obtained from the GRACE, CHAMP and COSMIC/FORMOSAT experiments were partially used. The International Reference Ionosphere (IRI) was also used; thus, the ground-based station data were indirectly considered. Within the model framework, the variations in the trough minimum position with longitude and local time were identified and studied in detail. The latitudinal and longitudinal variations in foF2 were also revealed and investigated. The constructed model more adequately reproduces variations in foF2 than the IRI-2016 model. The new model is available on the IZMIRAN website: http://www.izmiran.ru/ionosphere/sm-mit/.