HR: 0800h
AN: AE31A-0040    [Abstracts]
TI: Electrical activity and dust lifting on Earth and Mars
AU: * Renno, N O
EM: renno@alum.mit.edu
AF: Applied Physics Program, University of Michigan, Ann Arbor, MI 48109,
AU: * Renno, N O
EM: renno@alum.mit.edu
AF: Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109,
AU: Kok, J F
EM: jfkok@umich.edu
AF: Applied Physics Program, University of Michigan, Ann Arbor, MI 48109,
AU: Kok, J F
EM: jfkok@umich.edu
AF: Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109,
AB: Dusty phenomena, such as dust devils and dust storms, are the primary sources of atmospheric dust on both Earth and Mars, and are the most important currently active geological processes on Mars. Electric fields larger than 100 kV/m have been measured in terrestrial dusty phenomena. Such electric fields can substantially reduce the critical wind speed necessary for wind to move sand grains and can even directly lift them from the surface (Kok and Renno, 2006). On Mars, these electric fields have potentially important implications for atmospheric chemistry. Indeed, they dissociate water vapor and produce large amounts of hydrogen peroxide (Atreya et al., 2006). The emission of dust is driven by saltation, the process by which sand grains bounce on the surface and eject the smaller, harder to lift, dust particles into the air. We developed the first physically based numerical model for saltation that has been tested with data from measurements. Our model includes the generation of electric fields and the effects of electric forces on saltation. Preliminary results confirm that electric fields strong enough to directly lift particles from the surface can develop in terrestrial dust storms and dust devils. Our model results suggest that on Mars electric fields frequently exceed the 25 kV/m for the thin Martian air to break down. We thus expect electric discharges to commonly occur in Martian dust storms, which could have important implications for atmospheric chemistry and dust lifting.
DE: 3304 Atmospheric electricity
SC: Atmospheric and Space Electricity [AE]
MN: 2007 Fall Meeting