Coordinated rocket measurements on the D-region winter anomaly-II. Some implications

A diagnostic study is carried out on the results of a D-region winter anomaly program reported by Sechrist et al. (1969). This study examines the implications of the following possible causes of the winter anomaly: an enhancement in nitric oxide concentration; a decrease in the efficiency of electron loss; and an increase in energetic electron precipitation. It is concluded that the most likely of the three causes is a decrease in the efficiency of electron loss. This decrease in the efficiency is thought to be a consequence of changes in the relative abundance of hydrated positive ions above 80 km.