This paper presents for the first time a study of HINOTORI satellite measurements of electron density and electron temperature in the topside ionosphere exclusively for magnetic storm departures. Special focus was given to the major storm of 1 March, 1982. While large enhancements in T e characterize the day time storm response, marked increases in N e dominate the night time deviations. The night time N e enhancements which are rather remarkable during 0000-0400 LT are also found to be

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... ied by significant T e increases, by as much as 300 K. The statistical picture that emerges from the study of a large number of storms suggests significant nocturnal T e enhancements which correlate with the magnitudes of storm intensities. Ring current particles through charge exchange processes seem to be a major source of heat input to thermal electrons, though other sources may also be important.