Characteristics of storm time ion composition in the near-Earth plasma sheet using Geotail and RBSP measurements

Abstract

Solar wind particles and ionospheric O + ions influence the near-Earth plasma sheet and inner magnetospheric composition. We studied the behavior of H + , O + and He + ions (9–210 keV) for intense and moderate geomagnetic storms of solar cycle 23 and 24. An average energy density < ε > of ions over a given interval and flux enhancement is estimated using observations from satellites at different L values, namely STICS sensor on-board Geotail spacecraft and HOPE spectrometer on-board Radiation Belt Storm Probes. It provides a comprehensive understanding of the energy density variation of H + , O + and He + ions with the strength of IMF Bz, Psw, intensity of storms and L value. Statistically, we observed that (1) In the plasma sheet region, during main phase of the intense geomagnetic storm, and enhances, (2) is well correlated with Psw (CC = 0.86) and IMF Bz (CC = 0.85), (3) shows higher correlation (CC = 0.73) with Kp than (CC = 0.65), indicating a fairly good dependence on the strength of geomagnetic activity, (4) and dependence on L value indicates that O + /H + and He + /H + is more pronounced near L = 3. It is a cumulative extension of the previous studies on ion composition change which is in accordance with the existing picture of the plasma sheet and inner magnetosphere. [Figure not available: see fulltext.].