Magnetospheric Convection in a Hybrid-Vlasov Simulation

The Dungey cycle is a fundamental process governing large-scale plasma dynamics in near-Earth space. Traditionally, it has been studied using Magnetohydrodynamic (MHD) simulations and ionospheric observations. However, MHD models often oversimplify the complexities of reconnection dynamics and kinetic processes, while observational data tend to lack sufficient coverage. In this study, we investigate the Dungey cycle in a 3D hybrid Vlasov simulation. We also introduce a new method for quantifying reconnection rates in different Magnetic Local Time (MLT) sectors.

During the simulation, we quantify Dungey cycle motion by using reconnection rates in different MLT sectors and identify azimuthal convection channels on the dawn and dusk flanks, which are modulated by dayside reconnection events. Notably, we observe that the effective length of dayside reconnection fluctuates, even under steady solar wind conditions. Our results further reveal significant deviations from ideal MHD theory, which predicts that plasma flows within the magnetosphere should follow flux tube entropy isocontours. Instead, we demonstrate that plasma flows near reconnection sites and in the twilight zone exhibit more intricate and dynamic patterns, deviating from this idealized alignment.

This work validates the Vlasiator 3D simulation as a powerful tool for studying global plasma convection and provides a novel method of quantifying reconnection rates in simulation, as well as showing new results of azimuthal convection channels. Future work should focus on identifying the kinetic processes driving deviations in the alignment of plasma convection with flux tube entropy isocontours between MHD theory and the kinetic approach.