Statistical Study of Magnetopause Flux Ropes associated with Electron Diffusion Region (EDR) Encounters

Magnetopause reconnection is a fundamental driver of magnetospheric dynamics and plays an important role in transferring energy from the solar wind into the Earths magnetosphere. During magnetic reconnection, helical magnetic field structures known as flux ropes are commonly observed. Flux ropes are thought to be important for energy transfer in the reconnection process and can transfer flux from the magnetopause to the magnetotail. Previous work has investigated the properties of magnetopause flux ropes and highlighted the significance of flux rope interactions, including magnetic reconnection between two coalescing flux ropes, and secondary reconnection at the edge of flux ropes. The Earth-orbiting Magnetospheric Multiscale (MMS) mission measures the thermal electron and ion 3D distributions at 30 msec and 150 msec time resolution, respectively, and at spacecraft separations down to a few kilometres. This high-resolution data enables detailed study of the electron-scale dynamics of the magnetopause, and MMS has reported multiple encounters with the magnetopause Electron Diffusion Region (EDR). In this study, we investigate magnetopause flux ropes using data from MMS, focussing in particular on small-scale flux ropes observed near EDR encounters. We propose that such flux ropes are potentially recently formed by processes at the EDR, and characterise their properties, including their size, core field strength, and flux content. We compare the properties of the flux ropes observed at varying timespans from the EDR with the aim of understanding if such flux ropes are a distinct category of young flux ropes, or if they follow previously reported trends.