HR: 0800h
AN: SA31B-04    [Abstracts]
TI: Localized Ionization Patches on the Nightside of Mars and Their Dependence Upon Atmospheric Variations
AU: * Fillingim, M O
EM: matt@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, United States
AU: Peticolas, L M
AF: Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, United States
AU: Lillis, R J
AF: Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, United States
AU: Brain, D A
AF: Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, United States
AU: Halekas, J S
AF: Space Sciences Laboratory, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720-7450, United States
AU: Lummerzheim, D
AF: Geophysical Institute, University of Alaska, Fairbanks, AK 99775, United States
AU: Bougher, S W
AF: Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109, United States
AB: Using an electron transport model, we investigate the effect of ionization due to electron precipitation on the electron density and total electron content in the nightside ionosphere of Mars. As input we use typical tail electron spectra and recently reported auroral-like peaked electron spectra that appear to have undergone an acceleration process. The accelerated electron spectra increase the maximum number density and total electron content by nearly a factor of 3 over that produced by typical tail spectra. The regions of enhanced ionization are localized in space and correspond to magnetic cusps formed by the interaction of the Martian crustal sources with the interplanetary magnetic field. We find that our modeled peak ion production rates are several times less than previous calculations and that our calculated maximum ionospheric electron densities are less than recent observations. The main source of the discrepancy between our results and previous work appears to arise from differences in the neutral atmosphere profile. The upper atmosphere of Mars changes significantly with season and solar cycle. Likewise, peak ionization rates and maximum ionospheric electron number densities can also change significantly, with these quantities being minimum for conditions of large atmospheric scale heights; however, the thickness of the ionospheric layer is greatest under these conditions leading to a small net change in total electron content.
UR: http:sprg.ssl.berkeley.edu/matt/AGUS2007/mars/ DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2439 Ionospheric irregularities
DE: 2447 Modeling and forecasting
DE: 2455 Particle precipitation
DE: 5435 Ionospheres (2459)
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly