HR: 1340h
AN: A33E-1642    [Abstracts]
TI: Optically thick aerosol layers over clouds in the South-East Atlantic Ocean
AU: * Chand, D
EM: duli@atmos.washington.edu
AF: Dept. of Atmospheric Science, University of Washington, Seattle, WA 98195, United States
AU: Wood, R
EM: robwood@atmos.washington.edu
AF: Dept. of Atmospheric Science, University of Washington, Seattle, WA 98195, United States
AU: Anderson, T L
EM: tadand@atmos.washington.edu
AF: Dept. of Atmospheric Science, University of Washington, Seattle, WA 98195, United States
AU: Charlson, R J
EM: bobwhan@comcast.net
AF: Dept. of Atmospheric Science, University of Washington, Seattle, WA 98195, United States
AU: Hu, Y
EM: yongxiang.hu-1@nasa.gov
AF: NASA Langley Research Center, 11 Langley Blvd, Hampton, VA 23681, United States
AB: Aerosols have important impacts on the earth's radiation budget and the general circulation of the atmosphere. The magnitude of the solar absorption and scattering by aerosols is poorly constrained observationally and model estimates of the direct climate forcing (DCF) differ widely as a consequence. In order to better understand the role of aerosols and clouds on Earth's radiative budget, a space borne observing system, ‘Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations' (CALIPSO) was launched in June 2006. CALIPSO is part of the A-Train multi-satellite observing system and provides high temporal and spatial resolution lidar data that is designed to shed light on both aerosol and cloud physical properties and the interactions between them. We evaluate an existing method, and present a new method, to use CALIPSO Level-1 and Level-2 data to determine the optical thickness and Angstrom exponent of tropospheric aerosol layers overlying low clouds over the tropical South-East Atlantic Ocean. This region is frequently characterized by optically thick aerosol layers from southern African biomass burning advecting over extensive marine boundary layer clouds. In such a situation the effect of the aerosols on the top-of-atmosphere radiation is unclear and is sensitive to aerosol optical properties (especially aerosol optical depth and single scattering albedo) and the underlying cloud/surface albedo. We attempt to place observational constraints on the possible magnitude of the radiative effects of these aerosol layers using a combination of CALIPSO and MODIS satellite observations together with in-situ and surface-based observations of the single scattering albedo of the aerosol layers.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0321 Cloud/radiation interaction
DE: 0360 Radiation: transmission and scattering
DE: 1640 Remote sensing (1855)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting