1Space Sciences Laboratory, University of California, Berkeley
2Geophysical Institute, University of Alaska, Fairbanks
3Department of Atmospheric, Oceanic and Space Sciences,
University of Michigan, Ann Arbor
Auroral emission has been detected at every planet in the solar system which has a known global magnetic field and a substantial atmosphere. Recent Mars Express observations have shown that auroral emission also exists on Mars, which lacks a global magnetic field but does have localized regions of strong magnetic crustal sources. Additionally, accelerated electron spectra, reminiscent of those observed in Earth's auroral region, have recently been found in data from Mars Global Surveyor. These recent developments have prompted us to revisit the question of auroral emission on Mars. Previous calculations of auroral emission on Mars have neglected the effects of strong magnetic field gradients associated with converging fields near localized crustal sources. Also, previous calculations used typical sheath or tail electron spectra rather than the newly discovered accelerated spectra. We use observed MGS electron spectra as input into a new coupled electron transport and emission model which includes realistic magnetic field gradients. We analyze the effect the strong gradients have on the electron intensity in the upper atmosphere and the resulting excitation and ionization rates and emissions. In addition, we explore the range of excitation and ionization rates and emissions due to the different classes of observed electron spectra from sheath-like, to highly accelerated, to those observed during solar energetic particle events.
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