A Two-Spacecraft Study of Mars Induced Magnetosphere's Response to Upstream Conditions

Abstract:

We investigate the effects of the upstream solar wind magnetic field on the Martian induced

magnetosphere. This is a two-spacecraft study, for which we use Mars Express (MEX) magnetic field

magnitude data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS)

instrument and Interplanetary Magnetic Field (IMF) measurements and solar wind density and

velocity from the magnetometer (MAG) and the Solar Wind Ion Analyzer (SWIA) on board Mars

Atmosphere and Volatile EvolutioN (MAVEN), from November 2014 to November 2018. Equally

temporally spaced echoes appear in MARSIS' ionograms from which the electron cyclotron frequency

and eventually the magnitude of the local magnetic field can be calculated. At the same time solar

wind magnetic field data and solar wind parameters from MAG and SWIA respectively are utilized,

providing the solar wind input to the Martian system. We make real time comparisons of the IMF

and the induced magnetic field in the environment of Mars and we test the ratio B_(MEX) /B_(MAVEN)

against various parameters such as the solar wind dynamic pressure, velocity, density, Mach

number as well as the Martian seasons, latitudes and heliocentric distances. Additionally, we search

for disturbances in IMF which then can be traced in the induced field ultimately revealing the

response time of the induced magnetosphere to the solar wind behaviour.

MEX and MAVEN measurements combined allow us to investigate the response of the Martian

induced magnetosphere to the solar wind magnetic field. Real time comparisons of the IMF and the

induced field could help us understand the mechanisms controlling the structure of the Martian

induced magnetosphere.