The effect of neutral winds on the seasonal F-region variation

Abstract

Recent measurements of the O and O 2 densities in the thermosphere have supported earlier theories that the seasonal F-region ‘anomaly’ is caused by composition changes in the neutral gas. In the present paper, the contribution of neutral winds to the F-region seasonal variation is investigated. It is found that the meridional winds have a modulating effect on the seasonal F-region variation, enhancing the seasonal ‘anomaly’ for high solar activity at mid-latitudes, but reducing it at low latitudes and for low solar activity.