On the Prevalence of Lower-Hybrid Wave-Induced Electron-Scale Current Sheets related to Kelvin-Helmholtz Vortices during Southward IMF

Numerous spacecraft missions, theories and numerical modelling have studied the Kelvin-Helmholtz instability (KHI) excited at the Earth’s magnetopause at different scales. Important insights into particle transport and mixing as well as energy conversion related to the KHI were obtained from these studies and linked to processes such as magnetic reconnection and plasma turbulence.Recently, Blasl et al. (2022, 2023) and Nakamura et al. (2022 a, b) reported the first observations of the KHI during southward Interplanetary Magnetic Field (IMF) conditions from the Magnetospheric Multiscale (MMS) mission together with fully-kinetic Particle-In-Cell simulations designed for this event. The unprecedented resolution of the MMS mission together with large-scale kinetic simulation runs enabled a multi-scale study of the KHI. Their results showed the onset and evolution of secondary instabilities such as the Rayleigh-Taylor Instability responsible for globally deforming the vortex structures as well as the Lower-Hybrid Drift Instability (LHDI) leading to plasma mixing along the spine region of the vortices. Additionally, at 1 out of the 11 KH wave crossings they reported the observation of an electron-scale reconnecting current sheet at the interface between this mixing region and the magnetospheric plasma, as suggested by simulation results.In this study, we revisit this previously reported MMS KH event during southward IMF and study the remaining 10 vortex structures in detail. Especially, we will characterize the signatures of LHDI-induced plasma mixing from both simulations and observations at different evolutionary stages and discuss the prevalence and signatures of small-scale current sheets at these vortex structures. First results suggest the coexistence of vortex structures at different evolutionary stages in this KH event, which will be discussed in detail. A short discussion on the influence of the IMF on this mechanism will be given at the end of the presentation.