Detecting Small‐Scale Ionospheric Current Signatures Using MAVEN Observations | CU Experts

Abstract; Small‐scale (10 s of km) currents in the Martian atmosphere may result in atmospheric heating, ionization, discrete aurora, and atmospheric escape. We have developed a semi‐automated method to identify current signatures in the Martian upper atmosphere using perturbations in the local magnetic field. We use magnetic field measurements taken by Mars Atmosphere and Volatile EvolutioN to investigate the incidence of ionospheric current signatures on the nightside of the planet in regions of moderate to strong crustal fields ( 25 nT). We find that current signatures are uncommon in horizontal magnetic fields but are detected up to 100% of the time in magnetic cusp regions, where the field is nearly radial. Current signatures are more common post‐dusk than predawn, which is consistent with auroral emission. Current signatures are most common in the ionospheric dynamo region, where ion motion is driven by the neutral atmosphere and electrons are bound to magnetic field lines. The occurrence of current signatures does not appear to be influenced by interplanetary magnetic field direction, solar wind dynamic pressure, or solar extreme ultraviolet photon flux.

Hanley KG; Brain DA; Weber T; Mitchell DL; Espley J; Halekas JS; Lillis R; Thiemann E; Curry S

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