HR: 1340h
AN: A23C-0817    [Abstracts]
TI: A New, Physically Based Algorithm, for Retrieving Aerosol Properties over Land from MODIS
AU: * Levy, R C
EM: levy@climate.gsfc.nasa.gov
AF: SSAI, NASA GSFC Code 913, Greenbelt, MD 20771 United States
AU: * Levy, R C
EM: levy@climate.gsfc.nasa.gov
AF: Department of Meteorology, University of Maryland College-Park, College Park, MD 20442 United States
AU: Remer, L A
EM: remer@climate.gsfc.nasa.gov
AF: Laboratory for Atmopsheres, NASA GSFC Code 913, Greenbelt, MD 20771 United States
AU: Kaufman, Y J
EM: kaufman@climate.gsfc.nasa.gov
AF: Laboratory for Atmopsheres, NASA GSFC Code 913, Greenbelt, MD 20771 United States
AU: Mattoo, S
EM: mattoo@climate.gsfc.nasa.gov
AF: SSAI, NASA GSFC Code 913, Greenbelt, MD 20771 United States
AU: Dickerson, R R
EM: russ@atmos.umd.edu
AF: Department of Meteorology, University of Maryland College-Park, College Park, MD 20442 United States
AB: The MODerate Imaging Spectrometer (MODIS) has been successfully retrieving aerosol properties, beginning in early 2000 from Terra and from mid 2002 from Aqua. Over land, the retrieval algorithm makes use of three MODIS channels, in the blue, red and infrared wavelengths. As part of the validation exercises, retrieved spectral aerosol optical thickness (AOT) has been compared via scatterplots against spectral AOT measured by the global Aerosol Robotic NETwork (AERONET). On one hand, global and long term validation looks promising, with two-thirds (average plus and minus one standard deviation) of all points falling between published expected error bars. On the other hand, regression of these points shows a positive y-offset and a slope less than 1.0. For individual regions, such as along the U.S. East Coast, the offset and slope are even worse. Here, we introduce an overhaul of the algorithm for retrieving aerosol properties over land, to include more physical, less empirical assumptions. The new algorithm will include surface type information, instead of assuming globally fixed ratios of visible to infrared surface reflectance. It will include updated aerosol optical properties to reflect the growing aerosol retrieved from eight-plus years of AERONET operation. The effects of polarization will be including during lookup table creation, using vector RT calculations. Most importantly, the new algorithm does not assume that aerosol is transparent in the infrared channel. This new formulation will invert reflectance observed in the three channels (blue, red, and infrared), rather than performing iterative single channel retrievals.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0345 Pollution--urban and regional (0305)
DE: 0360 Transmission and scattering of radiation
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting