Changes of the near-Earth cross-tail current sheet associated with dipolarizations: a statistical study based on THEMIS observations

The aim of this study is to compare the macroscopic characteristic of the near-Earth current sheet before and after the passage of the dipolarizations. We took advantage of the three closely separated inner probes of the Time History of Events and Macroscale Interactions during substorms (THEMIS) mission. We selected dipolarisation events when two spacecrafts (i) were encircling the neutral sheet and (ii) were at the same location in the XYGSM plane, i.e. separated only in the ZGSM direction. Assuming 1D current sheet pressure balance, this particular configuration allowed to evaluate the thickness of the cross-tail current sheet, its current density and the associated JxB force before and after the passage of the dipolarization front for twenty-seven events. In this presentation, we report and discuss the assessment of the changes of these quantities from both superimposed-epoch and statistical analysis.