Possible magnetospheric Kelvin-Helmholtz vortex signatures near the post-noon magnetopause

We report on magnetospheric Kelvin-Helmholtz (KH) vortex signatures detected by THEMIS probes located near the post-noon magnetopause in the magnetosphere side for northward magnetosheath magnetic field. Oscillations of the magnetic field and of the ion velocity are measured with a period around 300 seconds. Once we moved into a magnetopause boundary coordinate system, the magnetic field and ion velocity oscillations display vortex-like signatures. Yet ion spectrograms show no strong magnetosheath/magnetosphere plasma mixing and these vortices appear mostly as magnetospheric vortices. Numerical simulations of the KH instability are presented to support this possibility.