Electrodynamics of the Martian dynamo region near magnetic cusps and loops

Strong and inhomogeneous remanent magnetization on Mars results in a complex pattern of crustal magnetic fields. The geometry and topology of these fields lead to atmospheric electrodynamic structures that are unique among the bodies of the solar system. In the atmospheric dynamo region (∼100−250 km altitude), ions depart from the gyropath due to collisions with neutral particles, while electron motion remains governed by electromagnetic drift. This differential motion of the charge carriers generates electric currents, which induce a perturbation field. The electromagnetic changes ultimately alter the behavior of the local ionosphere beyond the dynamo region. Here we use multifluid modeling to investigate the dynamics around an isolated magnetic cusp and around magnetic loops or arcades representative of the magnetic topology near, for example, Terra Sirenum. Our results show consistent, circular patterns in the electric current around regions with high local field strength, with possible consequences on atmospheric escape of charged particles.