Global features of Kelvin-Helmholtz waves at the magnetopause for northward interplanetary magnetic field

We investigate the global features of Kelvin-Helmholtz waves (KHW) at the low-latitude magnetopause for constant northward interplanetary magnetic field conditions, using global magnetohydrodynamic simulations. The root-integrated power (RIP) of X component of bulk velocity is employed to analyze the magnetopause mode of KHW along the boundary layer. The RIP distribution of the outer KHW is much broader than that of the inner one, and the maximum amplitude of global KHW occurs near the dawn/dusk terminator regions. In the dayside magnetopause, the phase of the waveform at middle latitudes leads to that at low latitudes, while the situation reversed in the nightside. The global evolution of KHW phases is a representation of an interesting feature that the axis of the Kelvin-Helmholtz vortex aligns with the geomagnetic field lines. We suggest that the reported features may also exist in other KHW active regions with flow-sheared plasma.