HR: 11:20h
AN: P22B-05    [Abstracts]
TI: Meteorological Conditions During Extreme Dust Events in North Africa
AU: * Ballantine, J C
EM: andyb@bren.ucsb.edu
AF: Department of Geography, University of California, Santa Barbara, Santa Barbara, CA 93106
AU: Okin, G S
EM: okin@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904-4123
AU: Mahowald, N
EM: mahowald@cgd.ucar.edu
AF: National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80305
AB: North Africa contains a wide diversity of dust sources, including the most productive dust sources on Earth. The emission of dust by these sources occurs in response to a wide range of surface and meteorological conditions. At several locations spanning representative geographies of North Africa, the landform, vegetation, and meteorological conditions were examined to identify the conditions associated with extreme (surface visibility ≤ 1 km) dust events. Landforms were identified using satellite imagery, vegetation using satellite imagery and measures of antecedent precipitation, and meteorological conditions using wind vectors and visibility measurements from the meteorological station in question. The time of year and wind vector that dominated dust production during these events varied by location and the prevalence of antecedent precipitation controls on dust emission through vegetation cover. The magnitude of the influence of antecedent precipitation through vegetation was found to be geographically variable. Stations in the Sahel and at the Saharan margin show a delayed suppression of dust emission after rainfall due to vegetation growth. Stations in the central Sahara show an immediate positive correlation between rainfall and dust production, possibly indicating the exposure or mobilization of fine sediments due to fluvial action. Meteorological data were also used to assemble wind speeds associated with extreme dust events at each of the stations studied. In this manner, an approximate regional measure of threshold velocity for dust emission could be measured.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 5415 Erosion and weathering
DE: 9305 Africa
SC: Planetary Sciences [P]
MN: Fall Meeting 2005