HR: 0800h
AN: A11A-0030    [Abstracts]
TI: MODIS Aerosol Optical Depth retrieval over South America: sensitivity on modeled aerosol from improved AERONET regional climatology
AU: * Pires, C
EM: cpires@cptec.inpe.br
AF: INPE, National Institute for Space Research, R Dutra, km 39, Cachoeira Pta, SP 12630000, Brazil
AU: Correia, A L
EM: acorreia@climate.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, United States
AU: Paixao, M
EM: melina@if.usp.br
AF: Institute of Physics, University of Sao Paulo, R do Matao, tr R, 187, Sao Paulo, SP 05508900, Brazil
AB: Atmospheric aerosols affect climate directly, through absorption and scattering of solar radiation, and indirectly, altering cloud formation mechanisms and properties. The radiation balance is a critical component of climate system and an increase in aerosol concentration causes a net change in radiation budget. Estimating aerosol direct radiative forcing combines, as input to radiative transfer codes, aerosol optical and microphysical models obtained through surface remote sensing and aerosol optical depth (AOD) from satellite data. Besides information on aerosol, atmospheric and surface conditions play also significant role along the estimation process. The purpose of this work is to study the sensitivity of AOD MODIS retrievals over South America to regional aerosol properties from AERONET ground-based data, and to typical atmospheric and surface conditions observed from satellite. Since May 2007, INPE counts on a regional system of aerosol retrieval from MODIS, based on NASA/GSFC algorithms. A new version of this product is under development, with changes on aerosol properties assumed inside the retrieval. Long-term measurements (1999-2006) from 9 AERONET sites over South America were used by LFA (Laboratory of Atmospheric Physics, USP) to produce a new set of regional aerosol models, allowing better characterization of aerosol types over this region. These models were combined with AOD from MODIS data as input to SBDART. The obtained results show that sensitivity of retrieved AOD on modeled microphysical and optical properties is much larger than that on atmospheric vertical profile. For instance, differences between the typical single scattering albedo observed at different AERONET sites create large discrepancies on regional scale MODIS retrievals. The results allow us to conclude that improvements on aerosol optical and microphysical modeling inside MODIS aerosol retrievals are critical in order to obtain a much more reliable tool on estimating aerosol radiative forcing. The use of AERONET climatology to produce regional aerosol models appears as a key method to this goal.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0360 Radiation: transmission and scattering
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting