GeophysicalResearchLetters RESEARCH LETTER Electrodynamics of the Martian dynamo region 10.1002/2013GL059130 near magnetic cusps and loops Key Points: Jeremy A. Riousset1, Carol S. Paty1, Robert J. Lillis2, Matthew O. Fillingim2, Scott L. England2, • The dynamo current forms in a Paul G. Withers3, and John P.M. Hale1 torus shape due to the E⃗× B⃗ drift of electrons 1School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA, 2Space Sciences • Asymmetries in the electric field Laboratory, University of California, Berkeley, California, USA, 3Astronomy Department, Boston University, Boston, are due to the collision-driven ion dynamics Massachusetts, USA • Magnetized region can alter charge carrier motion from lower to upper atmosphere Abstract 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 Supporting Information: structures that are unique among the bodies of the solar system. In the atmospheric dynamo region • Readme (∼100−250 km altitude), ions depart from the gyropath due to collisions with neutral particles, while • Figure S1 electron motion remains governed by electromagnetic drift. This differential motion of the charge • Figure S2 • Text S1 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 Correspondence to: modeling to investigate the dynamics around an isolated magnetic cusp and around magnetic loops or J. A. Riousset, arcades representative of the magnetic topology near, for example, Terra Sirenum. Our results show
[email protected] consistent, circular patterns in the electric current around regions with high local field strength, with possible consequences on atmospheric escape of charged particles.