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

• Published in: Journal of Geophysical Research, Washington, DC Washington, DC, 2000-06, Vol.105 (A6), p.12823-12832
• Main Authors: Schoendorf, J., Young, L. A., Oliver, W. L.
• Format: Article
• Language: English
• ISSN: 0148-0227; 2156-2202
• DOI: 10.1029/1999JA000369

Thermospheric density and temperature are often derived from ionospheric observables 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 experimental 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 balance equation; however, its profile shape and concentration are unknown. We develop a simple method for including hot O profiles in the ion temperature fitting equation by calculating hot O concentration as a function of altitude and including the hot O heat source in the ion energy equation. The technique is tested as a function of solar cycle for March equinox conditions, and a χ2 analysis indicates that the hot O is more likely to form a layer than a concentration profile which decreases as a function of altitude.