Variations in Topside Ion Temperature at Different Solar Activity Levels

Continuous operation of the ICON mission during 2021 and 2022 allows a description of the thermal plasma number density, composition and temperature to be obtained at low and middle latitudes near 600 km altitude, during low and moderate solar activity levels. With appropriate averaging of the data over a 2‐month period, we describe the latitude, longitude and local time distributions of the ion number density, composition and temperature to reveal systematic differences at different seasons and different levels of solar activity. We find that near the equator the daytime ion temperature near 600 km is relatively insensitive to changes in solar activity, while at middle latitudes the ion temperature is higher at low solar activity levels than at moderate solar activity levels. At night, the topside ion temperature cools toward the neutral gas temperature and the ion temperature is lower at low solar activity than at moderate solar activity. This behavior is modified by seasonal variations, which show that the presence of interhemispheric flows induced by F‐region winds changes the latitude distribution of ion density, composition and temperature.