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Description
Along with magnetic reconnection, Kelvin-Helmholtz (KH) waves are the main mechanisms controlling the solar wind-magnetosphere interaction. Kelvin-Helmholtz waves have been shown to be important for plasma transport into the magnetosphere, enabled by secondary processes such as reconnection, diffusion and wave-particle interactions. Here we use magnetohydrodynamical (MHD) simulations for studying how the Kelvin-Helmholtz instability (KHI) is modulated by the dipole tilt angle and IMF By. We find that KH wave activity on the magnetopause maximizes in the winter hemisphere and at dawn sector for positive IMF By. These asymmetries of KHI are caused by asymmetric draping of interplanetary magnetic field (IMF) in the magnetosheath and dawn-dusk asymmetry in magnetic reconnection, creating a broader boundary layer slowing the growth of KHI at dusk for positive By. These results are important for understanding field-aligned currents generated by the KH vortices and their effects on geomagnetic activity and its seasonal variation.