The importance of photoionization in the production of the daytime F-region at high latitudes during winter

Abstract

Solutions of the continuity equation for steady state conditions using reasonable values of photoionization, electron loss, and diffusion rates have indicated that photoionization can contribute a large part to F-region ionization at high latitudes in winter at sunspot maximum and might also be important at sunspot minimum. Most of the computations refer to an iso-thermal atmosphere in which thermal equilibrium exists between the neutral gas, electrons, and ions. It has been found, however, that the results are not altered significantly when account is taken of possible differences in temperature between the neutral gas, electrons, and ions unless the electron loss rate is dependent on the electron or ion temperatures. For large solar zenith angles, when electron production occurs at great heights, the F-layer is formed at a fixed height and assumes a constant shape, while its magnitude depends only on the height integral of the electron production and not on its form. These properties also apply when F2-ionization is produced at great heights by low energy ionizing particles.