HR: 16:50h
AN: SM34A-03    [Abstracts]
TI: Numerical Simulations of the Magnetic Topology Near Mars Auroral Observations
AU: * Liemohn, M W
EM: liemohn@umich.edu
AF: University of Michigan, Atmospheric, Oceanic, and Space Sciences Dept, 2455 Hayward St., Ann Arbor, MI 48109-2143, United States
AU: Ma, Y
EM: yingjuan@umich.edu
AF: University of Michigan, Atmospheric, Oceanic, and Space Sciences Dept, 2455 Hayward St., Ann Arbor, MI 48109-2143, United States
AU: Kozyra, J U
EM: jukozyra@umich.edu
AF: University of Michigan, Atmospheric, Oceanic, and Space Sciences Dept, 2455 Hayward St., Ann Arbor, MI 48109-2143, United States
AU: Nagy, A F
EM: anagy@umich.edu
AF: University of Michigan, Atmospheric, Oceanic, and Space Sciences Dept, 2455 Hayward St., Ann Arbor, MI 48109-2143, United States
AU: Winningham, J D
EM: dwinningham@swri.edu
AF: Southwest Research Institute, 6220 Culebra Rd, San Antonio, TX 78228, United States
AU: Frahm, R A
EM: rfrahm@swri.edu
AF: Southwest Research Institute, 6220 Culebra Rd, San Antonio, TX 78228, United States
AU: Sharber, J R
EM: jsharber@swri.edu
AF: Southwest Research Institute, 6220 Culebra Rd, San Antonio, TX 78228, United States
AU: Barabash, S V
EM: stas@irf.se
AF: Swedish Institute of Space Physics, PO Box 812, Kiruna, S-98128, Sweden
AU: Lundin, R
EM: rickard.lundin@irf.se
AF: Swedish Institute of Space Physics, PO Box 812, Kiruna, S-98128, Sweden
AB: Magnetohydrodynamic (MHD) simulation results are presented of the magnetic topology near the location where auroral emissions were observed. MHD simulations were conducted for this scenario with high spatial resolution centered on the region where the Mars Express SPICAM instrument observed intense aurora-like emissions (as published in Nature). This is also the region of strong magnetic field source in the Mars crust. A dense array of field lines were then extracted from the MHD simulation results in order to determine the most likely source population for these emissions. Specifically, two sources are being evaluated: solar wind electrons precipitating from the magnetosheath along open field lines, and atmospheric photoelectrons crossing the terminator on closed field loops. The ASPERA-3 ELS instrument on Mars Express observed photoelectrons near the time of the SPICAM measurements of auroral emissions, raising the possibility of photoelectrons as the auroral energy source. It is shown that closed field loops can indeed cross the terminator, thus depositing atmospheric photoelectrons into the nightside ionosphere, and possibly causing auroral/airglow emissions. However, for the specific location of the SPICAM auroral observations, the MHD results show only open field lines connected to the solar wind. The conclusion is therefore that the ELS in situ observations of atmospheric photoelectrons are most likely unrelated to the SPICAM limb scan optical measurements of auroral emissions.
DE: 2704 Auroral phenomena (2407)
DE: 2784 Solar wind/magnetosphere interactions
DE: 5408 Aurorae and airglow
DE: 5421 Interactions with particles and fields
DE: 5443 Magnetospheres (2756)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly