Solar Activity Variation of Electron & Ion Temperatures in Equatorial Topside Ionosphere

Abstract

The daytime electron and ion temperature <i>(T_e </i> and <i>T_i) </i> profiles in the topside ionosphere in the equatorial region are theoretically investigated for low and medium solar activity conditions. The available ion composition data from incoherent back-scatter radar and satellite <i>in situ </i> measurements are used in studying the thermal structure. The local and non-local electron heating rates due to photoelectrons are evaluated for these solar activity conditions. The results show that the plasma temperature at 400 km as well as at 1000 km increases from low to medium solar activity conditions, while it decreases at 700 km, The altitudinal extent of isothermal region around 500 km increases with increasing solar activity and the temperature gradient above the isothermal region is lower for medium solar activity as compared to low solar activity. The calculated temperature profiles are in fair agreement with the direct measurements of <i>T_e </i> and <i>T_i </i> taken at Jicamarca for similar conditions.