The importance of electron heat conduction in the energy balance of the F‐region

Abstract

Further analysis of the ionospheric electron heat balance using measurements by Atmosphere Explorer C has shown that electron heat conduction is important not only in the upper F‐region but throughout the lower ionosphere as well. The discrepancy between local heating and cooling rates reported by Brace et al., using similar AE‐C data, has been removed in the present study by selecting middle latitude passes in which horizontal gradients in Te are minimized, thus permitting the vertical or field aligned gradients to be resolved for use in the heat conduction equation. The inclusion of heat conduction consistently improves the agreement between theoretical and experimental Te6 profiles. Accordingly, poor agreement is obtained when using AE‐C data at low latitudes where large scale horizontal gradients in Te and Ne preclude the resolution of field‐aligned gradients in Te. Thus it would appear that current electron heating and cooling rates are consistent with the AE‐C observations. This study was limited to the effects of EUV heating at solar minimum, thus we do not imply that the electron energy balance is understood globally. Heating at high latitudes and nocturnal heating require further study.