Properties of the Main Phases of the Super Geomagnetic Storms (ΔSYM-H ≤ −250 nT) with Different Heliolongitudes

Abstract

Abstract We studied the properties of the main phases of 24 super geomagnetic storms (SGSs) (ΔSYM-H ≤ −250 nT) since 1981. We divided the SGSs into two subgroups: SGSs-I (−400 nT <Δ SYM-H ≤ −250 nT) and SGSs-II (ΔSYM-H ≤ −400 nT). Of the 24 SGSs, 16 are SGSs-I and eight are SGSs-II. The source locations of SGSs were distributed in the longitudinal scope of [E37, W66]. 95.8% of the SGSs were distributed in the longitudinal scope of [E37, W20]. East and west hemispheres of the Sun had 14 and 10 SGSs, respectively. The durations of the main phases for six SGSs ranged from 2 to 4 hr. The durations of the main phases for the rest 18 SGSs were longer than 6.5 hr. The duration of the SGSs with source locations in the west hemisphere varied from 2.22 to 19.58 hr. The duration for the SGSs with the source locations in the east hemisphere ranged from 2.1 to 31.88 hr. The averaged duration of the main phases of the SGSs in the west and east hemispheres are 8.3 hr and 13.98 hr, respectively. ∣ΔSYM−H/Δt∣ for six SGSs with source locations distributed in the longitudinal area ranging from E15 to W20 was larger than 1.0 nT · minute−1, while ∣ΔSYM−H/Δt∣ for the rest 18 SGSs was lower than 1.0 nT · minute−1.∣ΔSYM−H/Δt∣ for SGSs-I varied from 0.18 to 3.0 nT · minute−1. ∣ΔSYM−H/Δt∣ for eight SGSs-II varied from 0.37 to 2.2 nT · minute−1 with seven SGSs-II falling in the scope from 0.37 to 0.992 nT · minute−1.