Three-Dimensional Configuration of Induced Magnetic Fields Around Mars

Using over 6 years of magnetic field data (October 2014-December 2020) collected by the Mars Atmosphere and Volatile EvolutioN, we conduct a statistical study on the three-dimensional average magnetic field structure around Mars. We find that this magnetic field structure conforms to the pattern typical of an induced magnetosphere, that is, the interplanetary magnetic field (IMF) which is carried by the solar wind and which drapes, piles up, slips around the planet, and eventually forms a tail in the wake. The draped field lines from both hemispheres along the direction of the solar wind electric field (E) are directed toward the nightside magnetic equatorial plane, indicating that they are sinking toward the wake. These sinking field lines from the +E-hemisphere (E pointing away from the plane) are more flared and dominant in the tail, while the field lines from the -E-hemisphere (E pointing toward) are more stretched and pinched toward the plasma sheet. Such highly pinched field lines even form a loop over the pole of the -E-hemisphere. The tail current sheet also shows an E-asymmetry: the sheet is thicker with a stronger tailward J -> xB -> $\overrightarrow{J}\times \overrightarrow{B}$ force at +E-flank, but much thinner and with a weaker J -> xB -> $\overrightarrow{J}\times \overrightarrow{B}$ (even turns sunward) at -E-flank. Additionally, we find that IMF B-x can induce a kink-like field structure at the boundary layer; the field strength is globally enhanced and the field lines flare less during high dynamic pressure.

Automated summary

Using data from the Mars Atmosphere and Volatile EvolutioN mission, researchers conducted a statistical study on the magnetic field structure around Mars. They found that the magnetic field conforms to the pattern of an induced magnetosphere, with the interplanetary magnetic field from the solar wind draping around the planet and forming a tail. Field lines from both hemispheres sink toward the nightside magnetic equatorial plane, and there is asymmetry in the tail current sheet. The study also showed that the IMF B-x can induce kink-like field structures and enhance the field strength globally.