Identifying Boundary Layer Signatures of the Kelvin-Helmholtz Instability Using Hall-MHD Simulations and Virtual Spacecraft

Abstract:

It is well known that the Kelvin-Helmholtz instability can be generated by the velocity shear at the flanks of the planetary magnetospheres. Previous studies indicate that KHI and associated secondary processes (such as magnetic reconnection, kinetic Alfven waves and diffusion through the thin boundaries generated by the KHI) play a complementary part to the traditional reconnection process, thus contributing to the plasma heating and exchange between solar wind and magnetospheric plasma. However, sometimes KHI is difficult to identify as multiple processes can lead to the excitation of the magnetopause surface waves. Furthermore, sometimes the low latitude dayside reconnection can simultaneously occur with flank KHI, during the intervals of strongly southward IMF, and the generated structures may run into flank KH vortices. Therefore, it is important to develop detection techniques of the KHI in order to unambiguously identify it from other processes in the spacecraft data. In this presentation we show results of series of 2.5-dimensional Hall-MHD simulations with different virtual spacecraft trajectories through the KHI at different stages of the instability development, as well as simulations for pure reconnection. For the same plasma parameters across the magnetosphere and magnetosheath, just adjusting the direction of the magnetic field slightly at both sides of the boundary and assuming 3 different spacecraft trajectories can lead to 36 different KHI signatures. We characterize and compare these 36 KHI signatures with another set of simulations with virtual spacecraft, where magnetic reconnection starts as a primary process.