Three‐dimensional fluid simulations of plasma asymmetries in the Martian magnetotail caused by the magnetic anomalies

Abstract

Three‐dimensional single fluid nonideal MHD simulations of the solar wind interaction with Mars show that the strong magnetic anomalies in the Southern Hemisphere of Mars cause asymmetries in the near tail plasma. The simulations were run with the strong southern magnetic anomalies (SSMA) facing midnight, dawn, or dusk. The interplanetary magnetic field (IMF) was set to 1 nT in the By direction. The steady state results were then compared to the case when no surface magnetic field is present. The comparisons show regions of plasma depletion of ∼60% and enhanced plasma densities of over 200% for different SSMA orientations. The depleted plasma regions are similar to the plasma voids detected by Mars Global Surveyor. A minimagnetopause forms inside the magnetic pileup boundary for all three cases. When the SSMA are at the dusk terminator, the IMF drapes over dipole‐like surface magnetic fields, creating a magnetic field geometry reminiscent of a closed magnetosphere at Earth. When the SSMA are at dawn, the magnetic field geometry resembles that of an open magnetosphere at Earth, as the IMF reconnects substantially to the surface magnetic field. The complex magnetic field geometry for all three cases presented leads to large‐scale modification of the plasma flow in the tail.