MLT Dependence of Contribution of Charge Exchange Loss to the Storm Time Ring Current Decay: Van Allen Probes Observations

Much evidence has indicated that charge exchange with the neutral atoms is an important loss mechanism of the ring current ions, especially during the slow recovery phase of a geomagnetic storm. Most of the studies, however, were focused on the global effect of the charge exchange on the ring current decay. The effect on different magnetic local times and L shells has not been achieved. In this study, based on the in-situ energetic ion data (Level 3) from RBSPICE onboard two Van Allen Probes, we study the contribution of the charge exchange, calculated from the differential flux of ions, to the local ring current decay at different magnetic local times and radial distance. Results indicate that the charge exchange effect on the ring current decay shows clear MLT and L dependence. Our study provides important information of spatial distribution of the ring current loss evolution, which could be as a reference during the ring current modeling.