HR: 0800h
AN: A31C-0076    [Abstracts]
TI: Explicit Simulations of Convective-Scale Transport of Mineral Dust in Severe Convective Weather
AU: * Takemi, T
EM: takemi@depe.titech.ac.jp
AF: Tokyo Institute of Technology, Department of Environmental Science and Technology, G5-7, 4259 Nagatsuta, Yokohama, 226-8502 Japan
AB: Convective-scale transport of mineral dust in a severe weather setting is investigated with the approach of three-dimensional cloud-resolving simulations coupled with a dust emission-transport modeling. The simulations are intended to explicitly represent convective- and cloud-scale processes (such as updraft/downdraft, surface cold pool, precipitation) in a squall-line-type convective system, and are performed in an idealized setup in order to focus the primary mechanisms for convective-scale dust transport within a squall-line system. Initialized based on an observation in a severe duststorm case over the Gobi Desert in China, the cloud model well simulates an observational feature of the squall line and the associated duststorm in spite of a simplified model setup. Dust is emitted by strong surface winds associated with a well-developed surface cold pool, and is contained and mixed within the cold pool: a high dust concentration of greater than 10 mg m$^{-3}$ is induced. Owing to a high subgrid-turbulence mixing at the leading edge of the cold pool, the contained dust is transferred out of the cold pool and is entrained into the updraft region at the cold pool edge. Dust is then transported upward by the convective updraft which is continuously regenerated at the cold-pool leading edge and spread in the cross-line directions in a layered form at upper levels by system-scale circulation. Rearward dust transport relative to the leading edge of the system is pronounced at upper levels, according to the prevalent front-to-rear flow typically found in the squall-line systems. These convective-scale mechanisms for dust transport should be applicable to the cases in synoptic-scale cold-frontal rainbands containing a high thunderstorm activity.
DE: 3329 Mesoscale meteorology
DE: 3314 Convective processes
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting