A Statistical Study of Slow-Mode Shocks Observed by MMS in the Dayside Magnetopause

Abstract

We investigated characteristics of slow-mode shocks in the dayside magnetopause based on Magnetospheric Multiscale observations from September 2015 to February 2017. We analyzed 99 magnetopause crossings with reconnection jets and high time resolution data, out of which 20 crossings showed slow-mode shock signatures. Out of these crossings, one crossing showed slow-mode shock signature on both sides, and the rest had slow-mode shock signatures on one side, six (13) on magnetosphere (magnetosheath). The detection probability of slow-mode shocks in the magnetopause is ~20%, which is greater than that reported in the magnetotail. We also found 12 rotational discontinuities in these slow-mode shock events. The results also show that the observation of magnetosphere side slow-mode shock is favored when the number density ratio of magnetosheath to magnetosphere is small. No clear dependence of the existence of slow-mode shocks on other parameters such as, plasma beta, temperature anisotropy, and jet velocity, was found.