HR: 0830h
AN: P51C-0455    [PDF]
TI: Global Dispersal of Dust Following Impact Cratering Events on Mars
AU: Cho, J Y
EM: jcho@dtm.ciw.edu
AF: Carnegie Institution of Washington, Department of Terrestrial Magnetism 5241 Broad Branch Rd., N. W., Washington, DC 20015 United States
AU: * Stewart, S T
EM: sstewart@eps.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences 20 Oxford St., Cambridge, MA 02138 United States
AB: Hypervelocity impacts on Mars inject dust and vapors into the upper atmosphere. If the particles derived from the projectile or surface are widely distributed, impact events could drive intense weather patterns and perhaps transient climate change on Mars [Segura et al., {\it Science} (2002)]. Recent work on small impact events (100 m-sized projectiles) find that the mass of dust stirred into the troposphere may be equivalent to global dust storms [Nemtchinov et al., {\it JGR} (2002)]. For $\sim$10 to $\sim$100 km-sized impactors, dust and greenhouse vapors may be delivered to the upper troposphere and lower stratosphere, where the long residence time has the potential for regional or perhaps even global effects on the weather. In this work, we investigate the transport mechanisms that control the dispersion of dust injected into the upper troposphere from large impact events using a high-resolution global atmospheric dynamics model [Cho \& Polvani, {\it Science} (1996)]. The spreading rates, dispersal extent, and the potential for weather and climatological perturbations from both large ($\sim$10 km) and giant ($\sim$100 km) impactors are studied. The overarching goals in this study are to identify locations of persistent concentrations of aerosols and to estimate the smallest impact which may generate transient rainfall on Mars. From our simulations we find that modeling of the climatological response from giant, basin-forming events may assume nearly homogeneous aerosol distribution. However, understanding the atmospheric response to the more frequent, smaller cratering events requires explicit treatment of the spatial inhomogeneities caused by the atmospheric motion. Hence, 2-D or 3-D atmospheric models are needed. Intriguing flow concentrations in the southern hemisphere, which could serve as locations for storm fronts, are observed following large impacts over a wide range of conditions.
DE: 3346 Planetary meteorology (5445, 5739)
DE: 5400 PLANETOLOGY: SOLID SURFACE PLANETS
DE: 5409 Atmospheres--structure and dynamics
DE: 5420 Impact phenomena (includes cratering)
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting