Localized Oscillatory Dissipation in Magnetopause Reconnection

TL;DR

This paper uses MMS data to identify localized standing wave structures near the magnetopause that cause oscillatory energy dissipation during magnetic reconnection, revealing new insights into electron-scale processes.

Contribution

It uncovers highly localized (~15 electron Debye lengths) wave structures associated with oscillatory dissipation in asymmetric magnetopause reconnection, highlighting their dependence on guide magnetic field strength.

Findings

Localized standing wave structures with large electric fields identified.

Oscillatory dissipation characterized by alternating positive and negative J dot E.

Different locations of wave structures depending on guide magnetic field strength.

Abstract

Data from the NASA Magnetospheric Multiscale (MMS) mission are used to investigate asymmetric magnetic reconnection at the dayside boundary between the Earth's magnetosphere and the solar wind (the magnetopause). High-resolution measurements of plasmas, electric and magnetic fields, and waves are used to identify highly localized (~15 electron Debye lengths) standing wave structures with large electric-field amplitudes (up to 100 mV/m). These wave structures are associated with spatially oscillatory dissipation, which appears as alternatingly positive and negative values of J dot E (dissipation). For small guide magnetic fields the wave structures occur in the electron stagnation region at the magnetosphere edge of the EDR. For larger guide fields the structures also occur near the reconnection x-line. This difference is explained in terms of channels for the out-of-plane current (agyrotropic electrons at the stagnation point and guide-field-aligned electrons at the x-line).