Latitudinal Extent of the f-min Winter Anomaly Region during the DYANA Campaign.

Abstract

The f -min data obtained at eight ionosonde stations in the Far East during the DYANA campaign in January 1990 is analyzed to investigate the latitudinal extent of the ionospheric D-region winter anomaly region. The f -min anomaly is most intensified around the geographic latitudes of 40-45°N, becomes weaker toward higher and lower latitudes, and on occasion extends down to 26°N. Anomalous VLF and LF radio wave propagations strongly suggest the existence of D-region electron density enhancements during the winter anomaly. We hypothesize that this anomaly is triggered by planetary wave activity in the stratosphere and mesosphere.