A simulation of the field‐aligned plasma transport in the plasmaspheric plume during the 2015 St. Patrick's Day storm

In this paper, based on a calculated open E x B convection passage of a flux tube with subauroral polarization streams (SAPS) electric field involved, we use the Dynamic Fluid-Kinetic model to simulate the transport of major ion species (H+, He+, and O+) along magnetic field line (field-aligned) within the flux tube during the 2015 St. Patrick's Day storm. The drift trajectory is confirmed to be quite realistic based on observations and empirical models, meanwhile, the foot print of flux tube is initiated from subauroral latitudes toward polar latitudes along this drift pass. The Dynamic Fluid-Kinetic simulation displays interesting temporal evolution of the field-aligned plasma distribution at subauroral latitudes: The storm-enhanced density region continuously provides upward ion flux filling into plasmasphere, but the equatorial mass loading in plasmaspheric plume increases at first and then decreases. Further analyses found that the SAPS particularly impact the field-aligned transport of O+ particles from ionosphere to plasmasphere but have much less effect on H+ and He+ particles at subauroral latitudes, which causes significant enhancements of equatorial O+ density. The results show that the SAPS have significant effects on both drifting trajectory of the flux tube and associated field-aligned ion dynamics. This work reveals intimate storm time interaction between the inner magnetosphere and ionosphere which may affect the dynamics in outer magnetosphere or even at magnetopause with flux tube convection.