Cluster and MMS Simultaneous Observations of Magnetosheath High Speed Jets and Their Impact on the Magnetopause

Abstract

Escoubet et al. Cluster-MMS High Speed Jets and six magnetopause crossings were observed, respectively, on Cluster and MMS with a significant angle between the observation and the expected normal deduced from models. The angles observed range between from 11 • up to 114 •. One inbound magnetopause crossing observed by Cluster (magnetopause moving out at 142 km s −1) was observed simultaneous to an outbound magnetopause crossing observed by MMS (magnetopause moving in at −83 km s −1), showing that the magnetopause can have multiple local indentation places, most likely independent from each other. Under the continuous impacts of HSJs, the magnetopause is deformed significantly and can even move in opposite directions at different places. It can therefore not be considered as a smooth surface anymore but more as surface full of local indents. Four dust impacts were observed on MMS, although not at the time when HSJs are observed, showing that dust clouds would have been present during the observations. No dust cloud in the form of Interplanetary Field Enhancements was however observed in the solar wind which may exclude large clouds of dust as a cause of HSJs. Radial IMF and Alfvén Mach number above 10 would fulfill the criteria for the creation of bow shock ripples and the subsequent crossing of HSJs in the magnetosheath.

Higher-Order Statistics in Compressive Solar Wind Plasma Turbulence: High-Resolution Density Observations From the Magnetospheric MultiScale Mission

“…Both measurement techniques show good agreement for the electron density. An important caveat of the spacecraft potential is that it can be severely affected by dust strikes or similar inverted signatures discussed by [e.g., [66][67][68]. These events are characterized by an abrupt jump or drop in the density estimation which can affect the calculation of higherorder statistics [69,70].…”

Curlometer Technique and Applications

“…However, in another simultaneous event (Event 3) which was studied by Escoubet et al. (2020), the magnetopause current structures encountered by Cluster and MMS are totally different under the effect of the high‐speed jet in the magnetosheath. This suggests that similar current structures across a wide region can only remain during relatively stable solar wind conditions.…”

“…Above all, the magnetopause boundary layer sampled at two locations has a similar overall form for the magnetic field suggests that the MP should have a similar current structure across a wide region during specific IMF conditions. However, in another simultaneous event (Event 3) which was studied by Escoubet et al (2020), the magnetopause current structures encountered by Cluster and MMS are totally different under the effect of the high-speed jet in the magnetosheath. This suggests that similar current structures across a wide region can only remain during relatively stable solar wind conditions.…”

Mechanisms and Evolution of Geoeffective Large-Scale Plasma Jets in the Magnetosheath

“…A highly complex and non-linear interaction that ensues in this region has been the subject of rigorous study in the past few decades. In particular, the deceleration of the solar wind at the bow shock causes significant transient flux enhancements, which are also known as magnetosheath plasma jets [2,3]. These jets can interact with the magnetopause, the magnetic boundary shielding the Earth, which makes them geoeffective, that is they can cause disruptive events on either the Earth or in the space near the Earth [2,4,5].…”