Applying Magnetic Curvature to to MMS data to identify thin current sheets relative to tail reconnection

TL;DR

This study uses MMS data to analyze the distribution and thickness of thin current sheets in Earth's magnetotail, revealing dawn-dusk asymmetries and providing insights into tail reconnection processes.

Contribution

It introduces a novel application of magnetic curvature analysis to MMS data for assessing current sheet thickness across a broad radial range.

Findings

MMS spends more than twice as long in ion-scale thin current sheets pre-midnight.

Dawn-dusk asymmetry observed in the distribution of thin current sheets.

Results support theories linking thin current sheets to tail reconnection onset.

Abstract

Magnetic reconnection X-lines have been observed to be more common duskward of midnight. Thin current sheets have also been postulated to be a necessary precondition for reconnection onset. We take advantage of the MMS tetrahedral formation during the 2017--2020 MMS tail seasons to calculate the thickness of the cross-tail neutral sheet relative to ion gyroradius. While a similar technique was applied to Cluster data, current sheet thickness over a broader range of radial distances has not been robustly explored before this study. We compare this to recent theories regarding mechanisms of tail current sheet thinning and to recent simulations. We find MMS spent more than twice as long in ion-scale thin current sheets in the pre-midnight sector than post-midnight, despite nearly even plasma sheet dwell time. The dawn-dusk asymmetry in the distribution of Ion Diffusion Regions, as previously reported in relation to regions of thin current sheets, is also analyzed.