The lorentz force at the martian MPB: Observations from MAVEN data in the subsolar region

BERTUCCI, C.; MAZELLE, C.; ESPLEY, J.; GOMEZ, D.; MITCHELL, D.; ANDERSSON, L.; BOSCOBOINIK, G.; MORALES, L.; HALEKAS, J.

San Francisco

Congreso; AGU general assembly; 2020

AGU

The study of the current systems within the magnetosphere of Mars is essential to understand the energy and momentum transfer processes that lead to atmospheric escape. Since 2014 the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has been in elliptical orbit around Mars characterizing its atmosphere and plasma environment.In the present work we analyze data from the magnetometer (MAG), solar wind particleinstruments (SWIA and SWEA) and Langmuir Probe (LPW) to identify the Martian magnetic pileup boundary (MPB) and to characterize its magnetic morphology near the subsolar region. More specifically, we used the minimum variance analysis of the magnetic field (MVAB) to derive the boundary?s normal vector, its thickness and the associated current density. We find that within the MPB the minimum variance direction of the magnetic field is well defined, and it is approximately normal to the surface of the discontinuity derived from the existing conic section fits.We estimated the current density on the MPB in the subsolar region and measured the Lorentz force associated with it. We observed that the Lorentz force near the subsolar region is mostly due to the gradient of the magnetic field pressure and not the magnetic tension, which is consistent with a deflection of the solar wind ions. We also measured the MPB thickness, which is of the order of the solar wind ion inertial length. This suggests that in the subsolar region the Hall electric field dominates over the convective electric field and electron pressure gradient within the generalized Ohm?s Law.