Item

Abstract

The Harang reversal represents a critical region in the nightside magnetospheric and ionospheric convection and maps to the transition region between the near-Earth plasma sheet and the inner magnetosphere ring current. It forms during enhanced solar wind driving conditions, particularly during substorms. Previous studies have shown that the convection flows and current closure near the Harang reversal region exhibit repeatable, distinct variations and revealed a current closure relation between the Region 2 and the substorm field-aligned current systems. Our recent study comprehends this picture by showing the impact of Bursty Bulk Flows (BBFs) on the near-Earth pressure distribution and field-aligned current formation using the two-way coupled BATSRUS MHD-PIC simulation. The simulation results are also analyzed to reveal the particle distribution functions and energization during the evolution and propagation of the BBFs. In addition, distributed and heterogeneous measurements, such as from coherent and incoherent scatter radars, GNSS receivers, and ground magnetometers, have been fused together to build a holistic picture of dynamics in the Harang reversal region and deepen our system understanding of the nightside MI coupling dynamics.