IONOSPHERIC EFFECTS ASSOCIATED WITH GEOMAGNETIC AND SOLAR ACTIVITY DURING SUNDIAL IN SEPTEMBER-OCTOBER 1989
摘要：<正>We present the investigations of ionospheric disturbances as made during the SUNDIAL Campaign from September 8 to October 8,1989,based on data from Russia’s ionospheric stations.That period was characterised by disturbed geomagnetic conditions and high solar activity.Dst-variations,and data from ionosondes,magnetometers and riometers were used.Ne（h）-profiles were calculated for some disturbed time intervals. By analysing ionosphric parameters, it was possible to identify the following patterns in their behaviour. During world storms the F-region electron density decreases more than twice and maintains low values during 24 hours.This applies for both high- and midlatitude stations and is attributed to a rapid equatorward movement of the main ionospheric trough and to the decay of its equatorward wall.A proton flare caused the polar cap absorption （PCA） event which was observed at 30- hour intervals at the Norilsk latitude.At lower latitudes,the proton flare manifested itself as an increase in minimum reflection frequencies.
1997 International Symposium on Radio Propagation（ISRP’97）