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The Influence of Crustal Magnetic Fields on the Martian Bow Shock Location: A Statistical Analysis of MAVEN and Mars Express Observations

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posted on 2022-06-10, 15:39 authored by P Garnier, C Jacquey, X Gendre, V Génot, C Mazelle, X Fang, JR Gruesbeck, B Sánchez‐Cano, JS Halekas

Previous missions underlined the complex influence of the crustal magnetic fields on the Martian environment, including the plasma boundaries. Their influence on the bow shock is however poorly constrained, with most studies showing North/South differences attributed to the crustal fields, with various conclusions from little to strong variabilities. We analyze for the first time in detail the influence of crustal fields on the Martian shock location based on a multi-mission analysis (MAVEN and MEX). We introduce the angular distance to the strongest crustal field region in the southern hemisphere that induces the largest influence (but not unique, with a minimum pressure threshold analyzed). Its impact is at large scale (>40–60° around), is modulated by the local time of the strongest source region (with no influence beyond terminator), and maximizes when the Interplanetary Magnetic field (IMF) is stable during the preceding hours. We introduce a technique, that is, partial correlations, to provide a coherent picture for both MAVEN/MEX due to existing cross correlations with Extreme UltraViolet (EUV). A composite parameter is proposed, that represents the combined influence of EUV, magnetosonic mach number (two major drivers) and crustal fields, the latter having an impact of hundreds of km. The influence of crustal fields on the shock appears seasonal and correlated with the Total Electronic Content, revealing a large scale coupling between the crustal fields, the ionosphere and the shock. The crustal field influence on the shock is thus significant and complex, with a coupling to both the ionosphere below and the IMF above.

Funding

UKRI | Science and Technology Facilities Council. Grant Numbers: ST/V004115/1, ST/S000429/1, ST/W00089X/1

NASA grant. Grant Number: 80NSSC19K0562

History

Citation

Journal of Geophysical Research: Space Physics, Volume 127, Issue 5, May 2022, e2021JA030146

Author affiliation

School of Physics and Astronomy, University of Leicester

Version

  • AM (Accepted Manuscript)

Published in

Journal of Geophysical Research: Space Physics

Volume

127

Issue

5

Publisher

American Geophysical Union (AGU)

issn

2169-9380

eissn

2169-9402

Acceptance date

2022-04-04

Copyright date

2022

Available date

2022-06-10

Language

en

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