Equatorial trench at the magnetopause under saturation

TL;DR

This study analyzes the shape and distortions of the equatorial magnetopause under saturated reconnection conditions using GOES satellite data, revealing a trench and duskward shift caused by storm-time currents.

Contribution

It provides the first detailed statistical analysis of the equatorial magnetopause shape during saturation, highlighting the trench formation and duskward shift.

Findings

Magnetopause exhibits a prominent trench in the postnoon sector.

The shape is significantly distorted with a duskward shift.

Distortions are linked to storm-time currents and large-scale reconnection.

Abstract

Magnetic data from GOES geosynchronous satellites were applied for statistical study of the low-latitude dayside magnetopause under a strong interplanetary magnetic field of southward orientation when the reconnection at the magnetopause was saturated. From minimum variance analysis, we determined the magnetopause orientation and compared it with predictions of a reference model. The magnetopause shape was found to be substantially distorted by a duskward shifting such that the nose region appeared in the postnoon sector. At equatorial latitudes, the shape of magnetopause was characterized by a prominent bluntness and by a trench formed in the postnoon sector. The origin of distortions was regarded in the context of the storm-time magnetospheric currents and the large-scale quasi-state reconnection at the dayside magnetopause.