A modelling study of the effects of neutral air winds on electron content at mid-latitudes in winter

Abstract

A modelling study of the effects of neutral air winds on the electron content of the mid-latitude ionosphere and protonosphere in winter has been made. The theoretical models are based on solutions of time dependent momentum and continuity equations for oxygen and hydrogen ions. The computations are compared with results from slant path observations of the ATS-6 radio beacon made at Lancaster (U.K.) and Boulder, Colorado (U.S.A.). It is found that the magnitude of the poleward neutral air wind velocity has a strong effect on the general magnitude of the electron content, but that the daily pattern of electron content variation is relatively insensitive to changes in the magnitude and phase of the wind pattern. These results are in contrast with the behaviour reported previously (Sethia et al., 1983) for summer conditions. However, the night-time electron content is increased by advancing the phase of the neutral air wind and decreased by retarding it. It appears that day-to-day variations in the electron content pattern in winter cannot be explained as effects of changing neutral air winds, which again contrasts with the findings for summer. As in summer, the wind has a major effect on the filling of the protonosphere, but in opposite sense. It is argued that the effect of the neutral air wind on the ionospheric and the protonospheric electron contents depends on the duration of the poleward wind in relation to daylight and on whether or not the wind reverses direction whilst the ionosphere is sunlit.