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withers

HR: 0800h
AN: SA31B-05
TI: Simulations of the Mars Ionosphere during a Solar Flare
AU: * Withers, P
EM: withers@bu.edu
AF: Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, United States
AU: Wroten, J
EM: jwroten@bu.edu
AF: Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, United States
AU: Mendillo, M
EM: mendillo@bu.edu
AF: Center for Space Physics, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, United States
AU: Chamberlin, P
EM: Phillip.Chamberlin@lasp.colorado.edu
AF: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, CO 80303, United States
AB: Increased fluxes of X-rays during solar flares have been observed to enhance electron densities in the lower ionosphere of Mars. The photochemical timescale at these altitudes is on the order of minutes, so these electron density enhancements do not persist for substantially longer than the flare duration. We present the results of photochemical model simulations of the Mars ionosphere driven by temporally-varying solar fluxes, concentrating on 15 and 26 April, 2001. The Mars Global Surveyor (MGS) Radio Science (RS) instrument observed flare- enhanced electron densities on these dates. Solar fluxes are derived from the Flare Irradiance Spectral Model, which outputs the solar spectrum at 1 nm intervals from 0.5 to 195.5 nm every 1 minute. This empirical model is based on TIMED SEE, UARS SOLSTICE, GOES, and other observations. For a short period at the peak of a large solar flare, X-ray photoionization rates exceed EUV photoionization rates and the electron density peak altitude decreases by tens of kilometres. Simulations will be compared to MGS RS measurements of electron density profiles.
DE: 2400 IONOSPHERE (6929)
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly