Electron diffusion region embedded in a dipolarization front – an MMS/Cluster conjunction event

Abstract

Magnetic reconnection, a key energy conversion process in the Earth’s magnetosphere, has extensively been studied during the last few decades. Multi-point missions such as Cluster or Magnetospheric Multiscale (MMS) showed that magnetic reconnection takes place not only at large-scale stable magnetopause or magnetotail current sheets but also in transient localized current sheets.Here, we revisit the Dipolarization Front (DF) event, observed by the MMS spacecraft on September 08, 2018/14:51:30 UT in the Earth’s magnetotail. Previous studies reported that this DF shows a strong non-ExB type electron flow and a crescent-shaped distribution function, suggesting that this DF hosts an electron diffusion region (Marshall et al. JGR, 2020).To further characterize this special event, we (1) use conjunction observations of the MMS and Cluster spacecraft to investigate the event in the context of large scales and (2) apply the polynomial magnetic field reconstruction technique by Denton et al. (JGR, 2020) to characterize the embedded electron current sheet including its velocity and the X-line exhaust opening angle.