Night time geomagnetic effects of solar flares

A study of the normal run magnetogram data of two equatorial stations: Kodaikanal and Huancayo for a three year period (1969-1971), showed that solar flare effects on geomagnetic variation do occur even in the dark hemisphere. The night time geomagnetic effects of solar flares as observed at Kodaikanal are noticed to exhibit a distinct shape and possess sufficient amplitude in the H-component (>4r at the maximum). A comparative study of the characteristics of the night time geomagnetic effects of solar flares observed at Kodaikanal in relation to the simultaneous day time effects (SFE or Crochet) observed at Huancayo, revealed that the night time effects are characterized by slower rise and decay compared to day time effects