Winter anomaly of radio wave absorption and D-region modification

Results of a quantitative investigation of winter anomalous radio wave absorption are discussed and causes of the phenomenon are suggested. A correlation analysis between local wind and radio wave absorption is presented along with a time history of the development of the winter anomalous state of the D region in terms of electron density profiles. Winter anomaly precursors and the parameter normalized absorption contribution are considered. The relationship between the normalized absorption contribution and the development of the winter anomalous state of the D region is discussed.