Electron Jets in the Terrestrial Magnetotail: A Statistical Overview

Abstract

Abstract Electron jets, common transient phenomena for which the electron velocity is much larger than the ion velocity, play an important role in the energy dissipation and transport in the terrestrial and other planetary magnetospheres. Using the unprecedented high-resolution data provided by the Magnetospheric Multiscale mission from May to August in 2017, we perform one systematically statistical study on the electron jets in the terrestrial magnetotail for the first time. In total, 466 electron jet events are selected, which mainly concentrate in the region −25 < X < −17 R E, −14 < Y < 12 R E, and 0 < Z < 6 R E (R E is the Earth’s radius). The electron velocity within the electron jets is much larger than the local Alfvén speed, implying that these jets belong to super-Alfvénic flows. The average occurrence rate of electron jets is 0.217 events hr−1 in the X–Y plane and 0.189 events/hour in the Z–Y plane. The durations of the electron jets are mostly within 6 seconds with the average value of 2.89 seconds, which are much shorter than the duration of bursty bulk flows (BBFs) having the typical duration of several to tens of minutes. Through further analysis of the magnetic field, we find that electron jets can occur at five different structures, including 224 events detected during the crossing of current sheet, 57 events observed during the crossing of PSBL, 83 events around DFs, 79 events around magnetic holes, and 23 events around flux ropes. In addition, the relative positions of the electron jets in different structures are also identified in the present study. Our statistical results reveal the comprehensive features of electron jets in the terrestrial magnetotail, which can also be applied in the other planetary magnetosphere.