Seasonal features of geomagnetic activity: a study on the solar activity dependence

Abstract. Seasonal features of geomagnetic activity and their solar-wind–interplanetary drivers are studied using more than five solar cycles wind observations. This study involves a total 1296 storms varying intensity identified the Dst index from January 1963 to December 2019, 75 863 substorms SuperMAG AL/SML 1976 2019 145 high-intensity long-duration continuous auroral electrojet (AE) (HILDCAA) events AE 1975 2017. The occurrence rates storms, including moderate (-50nT?Dst>-100nT) intense (-100nT?Dst>-250nT) exhibit significant semi-annual variation (periodicity ?6 months), while super (Dst?-250 nT) HILDCAAs do not any clear seasonal feature. indices ap variation, exhibits an annual ?1 year). variations attributed speed Vsw coupling function VBs (where V = Vsw, Bs is southward component interplanetary magnetic field), respectively. We present detailed analysis dependencies on separated as odd, even, weak strong cycles.