Hot oxygen profiles for incoherent scatter radar analysis of ion energy balance

Thermospheric density and temperature are often derived from ionospheric ob servables measured by incoherent scatter radar (ISR) via solutions of the F region ion energy balance equation. However, this equation, consisting of an electron heat source balancing a neutral heat sink, can break down near the exobase, where the electron heat source can be too small by as much as 40%. An additional heat source is required, and theoretical and experimenta l studies point to a hot neutral oxygen (hot O) geocorona near the Earth's exobase to supply it. Hot O must therefore be included in the ion energy ba lance equation; however, its profile shape and concentration are unknown. W e develop a simple method for including hot O profiles in the ion temperatu re fitting equation by calculating hot O concentration as a function of alt itude and including the hot O heat source in the ion energy equation. The t echnique is tested as a function of solar cycle for March equinox condition s, and a chi(2) analysis indicates that the hot O is more likely to form a layer than a concentration profile which decreases as a function of altitud e.