The winter anomaly and medium-scale traveling Ionospheric disturbances (MSTIDs) detected during the DYANA campaign in 1990 are analyzed to investigate their characteristics and possible relationship to meteorological phenomena in the lower atmosphere. Anomalous f-min enhancements (FMEs), an indication of the winter anomaly, occurred around January occurrence are controlled by F-region electron density (foF2). 1.

No abstract

No 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.