Jets downstream of the Martian bow shock

Occurrence in the 2014–2024 period

¹ Department of Physics, Umeå University, 901 87 Umeå, Sweden
² HiQ, Stockholm, Sweden
³ Austrian Academy of Sciences, Space Research Institute, 8042 Graz, Austria

^★★ Corresponding author; herbert@herbertgunell.se

Received: 20 December 2024
Accepted: 5 March 2025

Abstract

Context. Dynamic pressure enhancements, known as magnetosheath jets, are plasma structures with a higher dynamic pressure than the surrounding plasma. They have been thoroughly studied at Earth and recently discovered around other planetary bodies. However, studies on jets outside of the terrestrial magnetosheath have only been performed as case studies.

Aims. We present the first statistical study of jets in the Martian plasma environment.

Methods. Our database was assembled using ten years of Mars Atmosphere and Volatile Evolution (MAVEN) mission data sampling various regions in the Martian plasma environment.

Results. Our database contains 82 645 jets, which have an average dynamic pressure increase of a factor of 2.34. The majority of jets are observed close to the bow shock in the magnetosheath. Most jets are driven by a combination of velocity and density enhancement, although the distribution is skewed toward density enhancement, as compared to jets at Earth. The jets are often colder than their background. The median scale size of Martian jets is 0.67 R_M.

Conclusions. Jets in the Martian plasma environment are similar to jets observed in the terrestrial magnetosheath, however, there are some differences. In Martian jets, the density enhancement dominates over the velocity; whereas in terrestrial jets, the velocity enhancement dominates over the density enhancement. Furthermore, jets are more deflected compared to the surrounding magnetosheath plasma. Martian jets are likely to be smaller than terrestrial jets, but they are larger relative to the scale size of the magnetosphere.