Are Dipolarization Fronts a Typical Feature of Magnetotail Plasma Jets Fronts?

TL;DR

This study analyzes five years of magnetospheric data to determine how often dipolarization fronts occur at plasma jet fronts in Earth's magnetotail, revealing they are less common than traditionally thought.

Contribution

It provides a comprehensive statistical analysis showing that classical dipolarization fronts are not the predominant feature at plasma jet fronts in the magnetotail.

Findings

Approximately 42% of jet fronts show large magnetic field changes.

Only 25% of these large changes are classical dipolarization fronts.

Most jet fronts have complex magnetic structures rather than classical DFs.

Abstract

Plasma jets are ubiquitous in the Earth's magnetotail. Plasma jet fronts (JFs) are the seat of particle acceleration and energy conversion. JFs are commonly associated with dipolarization fronts (DFs) representing solitary sharp and strong increases in the northward component of the magnetic field. However, MHD and kinetic instabilities can develop at JFs and disturb the front structure which questions on the occurrence of DFs at the JFs. We investigate the structure of JFs using 5 years (2017-2021) of the Magnetospheric Multiscale observations in the CPS in the Earth's magnetotail. We compiled a database of 2394 CPS jets. We find that about half (42\%) of the JFs are associated with large amplitude changes in $B_z$. DFs constitute a quarter of these large-amplitude events, while the rest are associated with more complicated magnetic field structures. We conclude that the ``classical" picture of DFs at the JFs is not the most common situation.