Double Superposed Epoch Analysis of Geomagnetic Storms and Corresponding Solar Wind and IMF in Solar Cycles 23 and 24

Abstract

The large (fluctuating) electric currents flowing at different regions in the magnetosphere and ionosphere during space weather events produce large fluctuations in the geomagnetic field lasting from several hours to several days in all latitudes (e.g., Akasofu, 1981;Gonzalez et al., 1994;Svalgaard, 1977). The field fluctuations at low latitudes are produced mainly by the enhanced low latitude magnetospheric ring current; they undergo 3-phase variations and are referred as geomagnetic storms. At high latitudes, the field fluctuations are produced mainly by the enhanced high latitude ionospheric auroral electrojet current; they undergo irregular variations and are referred as storm-time substorms or activities. At mid latitudes, the field fluctuations are the combined effect of the poleward extension of the low latitude fluctuations and equatorward extension of the high latitude fluctuations; they undergo 2-phase variations and are referred also as geomagnetic storms (e.g.

A fresh look at the intensity and impulsive strength of geomagnetic storms

“…To improve the time and spatial resolutions, the SymH index of 1-minute resolution was developed (Iyemori et al,1992) using the H-component data from up to 6 stations of MLS ~70º. The Dst and SymH indices have been used for studying not only the geomagnetic storms (e.g, Russell et al, 1973;Burton et al, 1975a;Gonzalez et al, 2011;Gopalswamy et al, 2015;Yermolaev et al, 2021;Balan et al, 2021;Manu et al, 2022Manu et al, , 2023 but also the disturbed upper atmosphere, ionosphere and magnetosphere (e.g., Fuller-Rowell et al, 1994;Manuucci et al, 2005;Tulasiram et al, 2010). For reviews, see Akasofu (1981Akasofu ( , 2021, Proless (1995), Daglis (1997), Luhr et al (2017) and Zong et al, (2021).…”