HR: 1340h
AN: A33C-0934    [Abstracts]
TI: Comparison of Angstrom Exponent and Optical Depth of Aerosol among POLDER-2, MODIS and AERONET over Ocean
AU: * WU, Y
EM: yhwu@atmos.washington.edu
AF: University of Washington, Department of Atmospheric Sciences,Box 351640/408ATG, Seattle, WA 98195 United States
AU: Anderson, T L
EM: tadand@atmos.washington.edu
AF: University of Washington, Department of Atmospheric Sciences,Box 351640/408ATG, Seattle, WA 98195 United States
AU: Goloub, P
EM: philippe.goloub@univ-lille1.fr
AF: Universit‚ des Sciences et Technologies de Lille 1, Batiment P5, Villeneuve d'Ascq, 59655 France
AU: Chu, A
EM: achu@climate.gsfc.nasa.gov
AF: JCET/UMBC-NASA GSFC, Code 613.2, Greenbelt, MD 20771 United States
AU: Dubovik, O
EM: dubovik@aeronet.gsfc.nasa.gov
AF: NASA/GSFC, Code 614.4, Greenbelt, MD 20771 United States
AB: The wavelength dependence of aerosol optical depth, commonly expressed as an Angstrom exponent (AE), is sensitive to aerosol size and thereby provides information on aerosol type. In-situ measurements indicate that AE is closely related to the sub-micron fraction of aerosol extinction or, equivalently, aerosol optical depth (AOD).Therefore, satellite retrievals of AOD and AE can potentially be combined to provide global maps of sub-micron AOD. Such maps, in turn, would serve a variety of scientific purposes such as constraining chemical transport models and helping to diagnose the global distribution of anthropogenic aerosols. Currently, the uncertainty of satellite-derived AE is not well characterized. In an effort to improve knowledge in this area, we compare AE and AOD from the over-ocean retrievals of two advanced satellites POLDER-2 on ADEOS-2 and MODIS on Terra to ground-based AERONET measurements. Eight AERONET maritime sites are selected during the POLDER-2 operational periods from April to October 2003. Generally, AODs at 865 nm and 670 nm show good correlation and agreement, respectively, while agreement for AE depends on the magnitude of AOD. AEs are poorly correlated when all data are considered. However, good correlation is found for AE when AOD at 865 nm is restricted between 0.1 and 1.0. Large discrepancies between satellite and AERONET values of AE are found when AOD is low. Our results indicate that the satellite retrieval of AE is unreliable at low AOD but, with proper restrictions, can provide a sufficiently accurate estimate of AE for use in global aerosol assessments.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 1640 Remote sensing (1855)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005