HR: 17:20h
AN: A54A-06    [Abstracts]
TI: Aerosol Optical Depth Retrievals From High-Resolution Commercial Satellite Imagery Over Areas of High Surface Reflectance
AU: * Vincent, D A
EM: davincen@nps.edu
AF: Naval Postgraduate School, 589 Dyer Rd, Rm 254, Monterey, CA 93943 United States
AU: Nielsen, K E
EM: knielsen@nps.edu
AF: Naval Postgraduate School, 589 Dyer Rd, Rm 254, Monterey, CA 93943 United States
AU: Durkee, P A
EM: durkee@nps.edu
AF: Naval Postgraduate School, 589 Dyer Rd, Rm 254, Monterey, CA 93943 United States
AU: Reid, J S
EM: reidj@nrlmry.navy.mil
AF: Naval Research Laboratory - Marine Meteorology Division, 7 Grace Hopper Ave, Stop 2, Monterey, CA 93943-5502 United States
AB: The advancement and proliferation of high-resolution commercial imaging satellites presents a new opportunity for overland aerosol characterization. Current aerosol optical depth retrieval methods typically fail over areas with high surface reflectance, such as urban areas and deserts, since the upwelling radiance due to scattering by aerosols is small compared to the radiance resulting from surface reflection. The method proposed here uses shadows cast on the surface to exploit the differences between radiance from the adjacent shaded and unshaded areas of the scene. Shaded areas of the scene are primarily illuminated by diffuse irradiance that is scattered downward from the atmosphere, while unshaded areas are illuminated by both diffuse and direct solar irradiance. The first-order difference between the shaded and unshaded areas is the direct component. Given uniform surface reflectance for the shaded and unshaded areas, the difference in reflected radiance measured by a satellite sensor is related to the direct transmission of solar radiation and inversely proportional to total optical depth. Using an iterative approach, surface reflectance and mean aerosol reflectance can be partitioned to refine the retrieved total optical depth. Aerosol optical depth can then be determined from its contribution to the total atmospheric optical depth (following correction for molecular Rayleigh scattering). Intitial results based on QuickBird imagery and AERONET data collected during the United Arab Emirates Unified Aerosol Experiment (UAE2) indicate that aerosol optical depth retrievals are possible in the visible and near-infrared region with an accuracy of ñ0.04.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005