Electron Cooling in the, F₂-Region at Low & Middle Latitudes

Abstract

Experimentally observed electron concentration, electron temperature and ion temperature profiles for ionospheric conditions, corresponding to low and middle latitudes, are used to calculate the electron cooling rates arising from the two major cooling mechanisms in the F₂-region, namely the electron.ion collisions and the electron impact-induced transitions among the fine structure levels of atomic oxygen. When electron concentration is low, the cooling due, to fine structure excitation of atomic oxygen dominates and conversely, when electron concentration is high the cooling due to oxygen ions dominates. For midlatitudes the electron concentration rarely exceeds 5 x 10⁵/cm³ and so, for these latitudes, the dominant cooling mechanism is the fine structure excitation of atomic oxygen. For low latitudes, the electron concentration is generally more than 6 x 10⁵/cm³ and thus, the electron-ion collisions become the dominant cooling mechanism.