MAVEN observations of tail current sheet flapping at Mars

Abstract

The Martian magnetotail is a complex regime through which atmospheric particles are lost to space. Our current understanding of Mars' tail continues to develop with the comprehensive particle and field data collected by Mars Atmosphere and Volatile EvolutioN (MAVEN). In this work, we identify periods when MAVEN encounters multiple current sheet crossings through a single tail traversal in order to understand tail dynamics. We apply an analysis technique that has been developed and validated by using multipoint measurements in order to separate the spatial and temporal properties associated with current sheet flapping. Events are classified into periods of steady flapping, due to a global motion of the current sheet, and kink‐like flapping, resulting from localized wave propagation along the tail current sheet. Out of 106 periods during which multiple current sheet crossings were observed, 20 were due to steady flapping and 10 from kink‐like flapping. A majority of the kink‐like events resulted from waves propagating in the opposite direction of the solar wind convection electric field, regardless of their location in the tail, unlike at Earth and Venus. This finding suggests that possible magnetosphere energy sources, whereby plasma is accelerated and removed from the Martian environment, are not located in the central magnetotail; rather, these waves may be driven by a source located at the tail flank based on the direction of the solar wind electric field. Therefore, by identifying potential sources of impulsive energy release in the tail, we may better understand mechanisms that drive atmospheric loss at Mars.

Effects of the Crustal Magnetic Fields and Changes in the IMF Orientation on the Magnetosphere of Mars: MAVEN Observations and LatHyS Results

“…These two arguments make unlikely to explain these measurements in terms of an IMF rotation, and, since the model considers effects derived from CFs, we conclude that the observed polarity change in the tail lobe is likely due to flapping (steady or kink) of the neutral current sheet. Similar signatures have been recently reported and studied based on MAVEN data (DiBraccio et al, , ). Indeed, multiple current sheet crossings are often observed on any given orbit as MAVEN crosses the Martian magnetotail, under stable IMF conditions.…”

“…Draping of the IMF is well reproduced in both direction and magnitude during the majority of the studied event. Numerical simulations do not reproduce the B x component between 08:00 and 08:14:30 UT where a change of sign is observed and difficult to interpret with a stationary picture of magnetic field draping, suggesting magnetotail flapping in the absence of IMF variabilities (DiBraccio et al, , ). The main difference at high altitudes concerns the predicted BS location, particularly during the flank BS crossing.…”

The Distribution of Two Flapping Types of Magnetotail Current Sheet: Implication for the Flapping Mechanism

“…Using the four‐point analysis of the Cluster (Escoubet et al, ), many studies demonstrated that the flapping CS can propagate as kink‐like waves from the midnight region toward both magnetotail flanks, with a velocity of several tens of km/s (Petrukovich et al, ; Rong et al, ; Runov et al, ; Sergeev et al, , ; Shen et al, ; Sun et al, ; Zhang et al, , ). CS flapping motions are observed not only in the Earth's magnetotail but also in the magnetotails of other planets, such as Mercury (Poh et al, ), Venus (Rong, Barabash, Stenberg, Futaana, Zhang, Wan, Wei, Wang, Chai, et al, ), Mars (DiBraccio et al, ), Saturn, and Jupiter (Volwerk et al, ).…”

Cluster Observations of a Dispersive Flapping Event of Magnetotail Current Sheet

“…Many studies based on the four‐point analysis of Cluster (Escoubet et al, ) demonstrate that the flapping motions can propagate as kink‐like waves from midnight toward both magnetotail flanks with the velocity of several tens of km/s (Petrukovich et al, , ; Rong et al, ; Runov et al, ; Sergeev et al, , ; Shen et al, ; Zhang et al, , ). In addition to Earth's magnetotail, the flapping motions are also commonly observed in planetary magnetotails, such as Mercury (Poh et al, ), Venus (Rong, Barabash, Stenberg, Futaana, Zhang, Wan, Wei, Wang, Chai, et al, ), Mars (DiBraccio et al, ), Saturn, and Jupiter (Volwerk et al, ).…”