MORPHOLOGY ANALYSIS OF MID AND LOW LATITUDE IONOSPHERIC RESPONSE TO GEOMAGNETIC STORM

Using the ionosonde data at 12 stations in East Asia, the response of mid and low latitude ionosphere to geomagneitc storm is analyzed for a typical case of August 27, 1978. Four processes affecting the mid and low latitude ionospheric disturbance morphology are discussed. Accompany with SSC, their appears the sudden increase of the peak density and decrease of its height; the storm circulation causes negative phase usually appears at the main phase of geomagnetic storm with the decrease of the peak density and increase of its height; TIDcan cause the small scale disturbances superposed in negative phase; and the movement of the equqatorial anomaly crest caused by neutral wind or electric field disturbances is the most important factor to determine the ionospheric storm morphology at stations near the crest.