A comparative study on geoeffective and non-geoeffective corotating interaction regions

Abstract

A long database of corotating interaction regions (CIRs) is used to investigate their geoeffectiveness. Among 290 CIR events identified during Solar Cycle 24 (2008–2019), 88 (30%) are found to be geoeffective in causing geomagnetic storms with the symmetric ring current index [SYM-H] peak ⩽-50nT, and 202 (70%) are non-geoeffective with the minimum SYM-H >-50nT. Based on a comparative study of the geoeffective and non-geoeffective CIRs, following results are obtained. Geoeffective and non-geoeffective CIRs have comparable duration (28±15hours, 26±14hours, respectively) and radial extent (0.33±0.17AU, 0.30±0.17AU, respectively), on average. While the mean solar-wind plasma speed during the geoeffective (503±70km s−1) and non-geoeffective (491±63km s−1) CIRs exhibits no statistical difference, the geoeffective CIRs have ≈25% higher peak plasma density, ≈45% higher ram pressure, ≈42% higher temperature, ≈39% higher interplanetary magnetic field (IMF) magnitude, ≈57% stronger IMF southward component, and ≈61% stronger reconnection electric field than the non-geoeffective events, on average. The auroral electrojet index [AE] and SYM-H are found to be, respectively, ≈58% and ≈192% stronger during the geoeffective CIRs than the non-geoeffective events. The typical characteristic solar-wind and geomagnetic activity parameters given in this article can be useful for space weather modeling and prediction purposes.