An observational study of the D-region winter anomaly and sudden stratospheric warmings

Abstract

An observational study of the link between the winter anomaly in ionospheric absorption and sudden stratospheric warmings for the 1967/1968 winter has been made. On the basis of the daily large-scale distributions of the absorption index, fmin, it is found that the winter anomaly during sudden warming could result from a NO increase induced by southward transport from the polar region, where NO is most abundant associated with a well-developed vortex in the D-region (large amplitude planetary wave). © 1982.