HR: 08:30h
AN: A11B-03    [PDF]
TI: Summer African Dust and Florida Thunder Storms: Are CRYSTAL-FACE Anvils Typical of the Subtropics?
AU: * Sassen, K
EM: ksassen@gi.alaska.edu
AF: Geophysical Institute Univ. of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Campbell, J R
EM: campbell@virl.gsfc.nasa.gov
AF: Geophysical Institute Univ. of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Prospero, J M
EM: jprospero@rsmas.miami.edu
AF: Rosenstiel School od Marine and Atmospheric Sciemce, Univ. of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 United States
AB: The Florida peninsula can be viewed as an outdoor laboratory for the study of the indirect effects of aerosols on the properties of deep convective clouds, and the possible subsequent impact on precipitation. Depending on the seasonal weather patters affecting the area, sources of aerosols can be continental, smoke-produced, oceanic, and, as long known, of Saharan Desert origin. During the recent CRYSTAL-FACE field campaign, a variety of in situ and remote sensing evidence shows that after transport across the mid-Atlantic Ocean, episodes of African dust were widespread in the region. This is a well-known summer-time phenomenon. In one study using aircraft ice nuclei (IN) data and ground-based polarization lidar measurements, the dust was observed to induce the glaciation of a slightly (about -5.0 to -8.0 degrees C) supercooled altocumulus cloud. Extrapolating the finding that African dust particles are especially active IN, it follows that the ingestion of boundary-layer Saharan aerosol could have a strong potential for modifying the microphysical content, dynamics and precipitation of summer thunderstorms in southern Florida. In the current study, we will attempt to identify connections between the characteristics of the intensively-studied thunderstorms and the nature of the dominant aerosols involved in cloud particle formation. As a first step, the near-continuous data record from the Micropulse Lidar, supplemented by Polarization Diversity Lidar data, will be used to monitor aerosol conditions. Backtrack and satellite analyzes, along with the University of Miami surface aerosol sampling record, will identify their source and likely cloud particle forming characteristics. The final stage of this research will search for correlations in in situ-derived cloud microphysical properties such as ice crystal concentration and type. If such connections are found, it must be recognized that the CRYSTAL-FACE dataset may not be representative of subtropical thunderstorms and the anvils derived from them.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 3314 Convective processes
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting