A Systematic Look at the Temperature Gradient Contribution to the Dayside Magnetopause Current

TL;DR

This study systematically analyzes how temperature gradients contribute to the magnetopause current system, revealing significant ion temperature effects that oppose classical currents and vary across boundary regions.

Contribution

It provides the first systematic quantification of temperature gradient contributions to magnetopause currents using MMS data.

Findings

Ion temperature gradients contribute up to 37% of ion diamagnetic current.

Temperature effects oppose classical Chapman-Ferraro currents, reducing total current.

Electron diamagnetic currents are significantly weaker than ion currents.

Abstract

Magnetopause diamagnetic currents arise from density and temperature driven pressure gradients across the boundary layer. While theoretically recognized, the temperature contributions to the magnetopause current system have not yet been systematically studied. To bridge this gap, we used a database of Magnetospheric Multiscale (MMS) magnetopause crossings to analyze diamagnetic current densities and their contributions across the dayside and flank magnetopause. Our results indicate that the ion temperature gradient component makes up to 37% of the ion diamagnetic current density along the magnetopause and typically opposes the classical Chapman-Ferraro current direction, interfering destructively with the density gradient component, thus lowering the total diamagnetic current density. This effect is most pronounced on the flank magnetopause. The electron diamagnetic current was found to be 5 to 14 times weaker than the ion diamagnetic current on average.