Association of Geomagnetic Storms with CME and Solar Wind Velocity during Solar Cycle-24

Abstract: Using a time series of geomagnetic storm (GMs) events between 2008 to 2019 obtained by selecting storms where disturbance short time Dst ≤-50nT, we have analysed the probability of association of Moderate, Intense and Severe events. We have found 73 GMs associated with Dst observed during 2008-2019 of solar cycle 24. Total 43% GMs linked with CMEs in which 3.8% are Halo CMEs and 1.9% are Partial Halo CMEs associate with severe GMs. Severe GMs are observed to be the largest 5.5% of all GMs in which 5.1% severe GMs relate with CMEs. During the period of study, we observed total 169 CMEs associated with GMs in which 5.3% CMEs associated with severe GMs. During the period of study, we have analysed the correlation between GMs magnitude with CME speed and SWpv, with correlation coefficient -0.736 and -0.975, but for intense GMs the correlation coefficient obtained -0.620 and -0.578. Our study shows that CMEs in which Halo CMEs and SWpv are good parameter to study the severe GMs. The study also analyses on the daily average database that GMs of largest magnitude with -127nT occurred in year 2015, which is the strongest GMs of solar cycle 24.

Keywords: Geomagnetic storm (GMs), Disturbance short time (Dst), Coronal Maas Ejection (CME), Solar wind plasma velocity (SWpv), Solar Cycle 24.