Chain of responses of geomagnetic and ionospheric storms to a bunch of central coronal hole and high speed stream of solar wind

Results of analysis of the proxy of Coronal Hole (CH) Power index, Pch, combined with the high speed streams HSS of solar wind for a period from 2011 to 2019 are presented. It is found that the long-term variation of Pch index shows a trend of growing Pch towards the minimum of solar cycle while most of other identities of solar activity tend to diminish. Superposition of fast solar wind of CH origin with slow SW of CME's origin synchronized with SC explains increasing/decreasing solar wind speed Vsw at L1 point. Total 136 geo-effective Pch/HSS storms are selected with 4 criteria: (1) 3-day increment ΔPch ≥ 90 i.u. where ΔPch = Pch(1d_dmax) – Pch(-3d_dmin); (2) the Pch event is consistent with data of VizieR catalogue of CHs; (3) during 1–4 days after Pch(1d_dmax) the jump of HSS solar wind speed ΔVsw exceeds 50 km/s where ΔVsw = Vswmax(t0 + Δt) - Vswmin(t0) for running time window Δt ≤ 24 h; (4) index kp ≥ 3 occurs during 48 h after zero time t0. Example of moderate storm on 27–28 September 2019 is provided to illustrate Pch/HSS related storm. The superposed epoch analysis is applied to the solar wind speed Vsw, geomagnetic AE, AU, AL, aa, ap, kp, Dst indices and planetary ionosphere TEC-based Wp index during time t0-24 h ≤ t < t0 + 48 h with zero time t0 = 0 at Vswmin. The indices are chained by increasing time lag (delay) of index peak observed after t0 for more than 50% of Pch/HSS storms while the percentage occurrence of peak indices for minimum lag Δt = 8 h after Vswmin was decreasing. The highest rank belongs to AU, kp, ap and aa indices which demonstrate more than 50% of storms with lag Δt = 8 h followed by AE, AL and Vswmax (Δt = 10 h), Wp index (Δt = 13 h) and Dst index (Δt = 15 h). The model relations indicate potential to derive predictions of chain of the peak storm indices in the solar wind, magnetosphere and ionosphere from 1 to 5 days in advance when the relevant increment of Pch index is observed.