Electron temperature and electron density in the F-region of the ionosphere. II. The role of atomic oxygen and molecular nitrogen

Abstract

Atomic oxygen and molecular nitrogen play several important roles in the processes that control the thermal balance of the electron population near the F-region peak. Both O and N 2 are ionised by EUV radiation and produce photoelectrons. Ion exchange with N 2 contributes to the recombination of O 2+ and in this way controls the equilibrium electron density. In the transfer of photoelectron energy to thermal electrons competition arises from ionisation and excitation of oxygen and nitrogen. Finally, of the processes by which thermal electrons lose energy, the three most important are Coulomb collision with ionised oxygen, excitation of the fine-structure states of neutral oxygen and vibrational cooling by molecular nitrogen. A simple model expresses all these processes and accurately describes the observed relationship between electron temperature, electron density and solar flux.