THE MAGNETIC FIELD STRUCTURE OF THE MARTIAN MPB FROM MAVEN DATA

GABRIELA BOSCOBOINIK; CÉSAR BERTUCCI; CHRISTIAN MAZELLE; DANIEL GÓMEZ

Viena

Congreso; EGU General Assembly 2019; 2019

The study of the current systems within the magnetosphere of Mars is essential tounderstand the energy and momentum transfer processes that lead to atmosphericescape. Since 2014 the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft hasbeen in elliptical orbit around Mars characterizing its atmosphere and plasma environment.In the present work we analyze data from the magnetometer (MAG), and solar windparticle instruments (SWIA and SWEA) to identify the Martian magnetic pileup boundary(MPB) and to characterize its magnetic morphology.More specifically, we used the minimum variance analysis of the magnetic field (MVAB) toderive the boundary?s normal vector, its thickness and the associated current density. Wefind that within the MPB the minimum variance direction of the magnetic field is welldefined, and it is approximately normal to the surface of the discontinuity derived from theexisting conic section fits. This analysis also reveals that the MPB behaves either as arotational or a tangential discontinuity in the magnetohydrodynamical sense.As reported in previous works, the thickness of the discontinuity in the normal direction isof the order of the solar wind proton inertial length and not the gyroradius, suggesting thatthe role of Hall effects near the MPB is important. We then studied the relative importanceof the electric Hall field with respect to the convective electric field within the generalizedOhm's Law.