IMF B y ‐Controlled Dawn–Dusk and Hemispheric Asymmetries of Kelvin–Helmholtz Waves and Reconnection Geometry Under Negative Dipole Tilt

Abstract Along with magnetic reconnection, Kelvin‐Helmholtz (KH) waves are the main mechanisms controlling the solar wind‐magnetosphere interaction, enabling plasma transport into the magnetosphere due to secondary reconnection, diffusion and wave‐particle interactions. In this paper we use global magnetohydrodynamical (MHD) simulations for studying how the Kelvin‐Helmholtz instability (KHI) is modulated by interplanetary magnetic field (IMF) during negative dipole tilt. We find that KH wave activity on the magnetopause maximizes in the winter hemisphere and at dawn sector for positive IMF . These asymmetries of KHI are caused by dawn‐dusk asymmetries of velocity shear on the magnetopause and draped IMF in the magnetosheath. These factors are linked to magnetic reconnection geometry, which also creates a broader boundary layer, slowing the growth of KHI at dusk for positive . These results are important, for example, for understanding field‐aligned currents generated by KH vortices and their ionospheric effects during different seasons and IMF conditions.