A possible explanation of weak cyclic variations of the absorption of radio waves at high latitudes

The contribution of electron streams to the ionization of the lower atmosphere at high latitudes has been estimated to investigate possible reasons for observed differences in the variability of the absorption of radio waves at middle and high latitudes. The electron concentration in the interval from 75 to 85 km varies less over the period of the solar cycle at high latitudes than at middle latitudes. The electron concentration at altitudes of 80 to 88 km is 10-15% higher at high latitudes than at middle latitudes during periods of intense solar activity, and up to 30% higher in quiet periods. Results of the analysis indicate that observed differences in the variability of radio wave absorption may be due to the presence at high latitudes of background electron streams which display little variability with the solar cycle.