Statistical Survey of Thin Current Sheets in Earth's Magnetotail: MMS Observations

Abstract

Thin current sheets (TCS) formed in Earth's magnetotail and hosting magnetic field line reconnection are important element of magnetospheric dynamics. In this paper, a statistical survey of 163 TCS crossing events in Earth's magnetotail using observations by MMS during 2017–2020 is performed. We find that magnetotail TCSs typically have a very strong current density primarily carried by electrons, with a thickness of a few ion inertial lengths. Our statistical results reveal different characteristics between TCSs located on the duskside and dawnside. Specifically, we find that TCSs on the duskside have a smaller thickness, higher current density, and stronger Hall electric field than on the dawnside. Our results also show that there is a correlation between the TCS thickness and the Hall electric field magnitude, with a stronger Hall electric field present in thinner TCSs. Our statistics results confirm previously reported key TCS dawn‐dusk asymmetries, with the main advance of directly measurable plasma currents. TCS characteristics of the presented data set will be useful for initialization of realistic numerical simulations and theoretical investigations of TCS instabilities resulted in various dynamical models of the magnetotail.