Characteristics of the Flank Magnetopause: THEMIS Observations

TL;DR

This study uses THEMIS satellite data to compare the properties of the Earth's flank and dayside magnetopause, revealing differences in thickness, current density, and dawn-dusk asymmetry.

Contribution

It provides new observational insights into the macroscopic properties and asymmetries of the flank magnetopause using THEMIS data.

Findings

Flank magnetopause is thicker than dayside.

Lower current density at the flank.

Persistent dawn-dusk asymmetry observed.

Abstract

The terrestrial magnetopause is the boundary that shields the Earth's magnetosphere on one side from the shocked solar wind and its embedded interplanetary magnetic field on the other side. In this paper, we show observations from two of the Time History of Events and Macroscales Interactions during Substorms (THEMIS) satellites, comparing dayside magnetopause crossings with flank crossings near the terminator. Macroscopic properties such as current sheet thickness, motion, and current density are examined for a large number of magnetopause crossings. The results show that the flank magnetopause is typically thicker than the dayside magnetopause and has a lower current density. Consistent with earlier results from Cluster observations, we also find a persistent dawn-dusk asymmetry with a thicker and more dynamic magnetopause at dawn than at dusk.