A Model of the Influence of Neutral Air Dynamics on the Seasonal Variation in the Low Ionosphere

Recently it has become clear that the phenomena in the ionospheric D-region are determined to a great extent by dynamical processes in the strato-mesosphere D-region. In this respect much attention is paid to the study of the winter anomaly (WA) phenomenon on medium and short radiowaves, in which the meteorological character of the lower ionosphere is most prominent. Significant experimental data about the variations of the electron concentration, N, ion composition, temperature and dynamic regime during WA permit a better understanding of the character of the physical processes in the middle atmosphere. The influence of the neutral wind on the seasonal variation of the electron concentration N for the altitude interval 90 or = z or = 120 km, where the ratio upsilon sub in/omega sub i, of the ion-neutral collision frequency, upsilon sub in and the ion gyrofrequency, omega sub i decreases from 40 to 1 was evaluated. CIRA-72 is used as a model of the zonal wind.