The field-aligned plasma transport in the plasmaspheric plume during a magnetic storm: A simulation study

The Storm Enhanced Density (SED) plume and plasmaspheric plume are defined as regions filled with dense and cold plasma and are associated with enhanced geomagnetic activities, particularly magnetic storms. The storm-time interaction of plumes has been intimately connected to Subauroral Polarization Streams (SAPS) electric field and contributes to a comprehensive understanding of magnetosphere-ionosphere coupling. Based on a calculated open drift trajectory of a flux tube with SAPS electric field involved, we use the Dynamic Fluid-Kinetic (DyFK) model to simulate the transport of major ion species (H⁺, He⁺ and O⁺) along magnetic field line (field-aligned) within the flux tube during storm time. The drift trajectory is confirmed to be quite realistic compared to observations and empirical models meanwhile the foot print of flux tube is initiated from subauroral latitudes toward polar latitudes along this drift pass. The DyFK simulation displays interesting temporal evolution of the field-aligned plasma distribution between plumes at subauroral latitudes. Further analyses show that the SAPS have prominent impacts on magnetospheric convection and associated mass loading at magnetospheric equator. This work reveals intimate storm-time interaction of inner magnetosphere and ionosphere which may affect the dynamics in outer magnetosphere or even at magnetopause with flux tube convection.