Different Faces of the Martian Magnetosphere

Abstract

The Martian magnetosphere contains components of the induced and intrinsic magnetospheres. Since we can not get a global snapshot of the magnetosphere we use a statistical picture based on a large number of measurements. Depending on the choice of coordinate system and the data selection we can observe different faces of the Martian magnetosphere. If we map data in the Martian Solar Electric coordinate system, then we can separate the induced features of the magnetosphere which appears similar to the magnetosphere of Venus. If we use the Martian Solar Orbital coordinate system and select together the orbits with positive and negative $B_y$-component of the IMF, then the effects related to draped magnetic field and the high order harmonics of the crustal magnetic field are significantly weakened because of averaging over many orbits and a dipole-like magnetosphere of Mars becomes visible. If we select separately the orbits with positive and negative $B_y$-component we observe a twist of the magnetotail in the direction determined by the sign of $B_y$ that is typical for a hybrid magnetosphere with the induced and intrinsic components. The intrinsic and induced components are also well separated when we select the orbits with northward IMF. Then we observe the features that are somewhat similar to those at the Earth magnetosphere. When we use the MSO coordinates and separate by the phase of Mars rotation, the tail topology occurs more complex. This indicates that the effects of the local crustal magnetic field turn out as being also important.