Dependence of geomagnetic activity during magnetic storms on the solar wind parameters for different types of streams: 2. Main phase of storm

Abstract

The paper analyses the development of the main phase of magnetic storms with Dst ≤ −50 nT, the interplanetary source of which consists of eight types of solar wind streams: magnetic clouds (MC, 17 storms); corotating interaction regions (CIR, 49 storms); Ejecta (50 storms); compressed region (Sheath) before Ejecta Sh_E (34 storms); the Sheath before a magnetic cloud Sh_MC (6 storms); all Sheath before all ICME, Sh_E + Sh_MC (40 storms); all ICME, MC + Ejecta (67 storms); and an indeterminate type of stream IND (34 storms). Threshold value estimates of the integral electric field sumEy to attain an intensity level of moderate (Dst ≤ −50 nT) and strong (Dst ≤ −100 nT) magnetic storms indicate a tendency toward their dependence on the type of magnetic storm source. It can be assumed that, on average, Sheath before ICME have threshold values 1.5 times less that ICME themselves.