HR: 1340h
AN: A33C-0921    [Abstracts]
TI: Sensitivity of IR radiative properties of dust aerosols to their mineralogical composition: implications for IR remote sensing
AU: * Lafon, S
EM: sandra.lafon@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332 United States
AU: Sokolik, I N
EM: isokolik@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332 United States
AU: Darmenov, A
EM: anton.darmenov@eas.gatech.edu
AF: School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332 United States
AU: Legrand, M
EM: Michel.Legrand@univ-lille1.fr
AF: Laboratoire d'Optique Atmospherique, UMR/CNRS 8518, Universite des Sciences et Technologies de Lille, Villeneuve d'Ascq, 59655 France
AU: Rajot, J
EM: rajot@ird.ne
AF: Institut de recherche pour le developpement, UR-049, BP 11416, Niamey, Niger Niger
AU: Gaudichet, A
EM: gaudichet@lisa.univ-paris12.fr
AF: Laboratoire Interuniversitaire des Systemes Atmospheriques, UMR/CNRS 7583, Universites Paris 12 et Paris 7 61 Avenue du General de Gaulle, Creteil, 94010 France
AB: The frequent presence and large amount of mineral dust particles in the atmosphere make them an important factor in climate/radiation processes as well as remote sensing. In particular, due to their large size, dust particles strongly interact with the thermal IR radiation. This interaction is controlled to a large extent by the mineralogical composition because the minerals commonly present in the atmosphere have distinct absorption spectra in the IR region. However, determination of the size-resolved mineralogy of atmospheric dust has been proven difficult due to both the complex nature of dust mixtures, which can vary in space and time, as well as known problems in quantifying the mineralogy itself. This study investigates how the uncertainties in the determination of the mineralogical composition of dust aerosol mixtures along with uncertainties caused by the assumptions under which this information is incorporated in the radiative transfer model affect the prediction of dust radiative properties in the thermal IR. Based on an electron microscopy size-resolved mineralogical analysis, we determined the mineralogical composition of two laboratory-generated dust aerosols representative of active dust production regions in the Sahel and China. Using these data, we performed an extensive sensitivity study of IR optical properties to investigate the extent to which they are affected by mineralogical parameters. Then calculations of IR fluxes were performed for some cases to further investigate how the mineralogical parameters affect calculations of IR radiative forcing of dust at a regional scale as well as the IR radiance in the narrowband channels representative of satellite and ground based sensors. The modeling results were examined along with observations from the MODIS and ground-based multi-channel IR radiometer in dust-laden atmospheric conditions. The results of this study will be presented and discussed along with the recommendations on the incorporation of the mineralogical composition into dust radiative models. The potential of using IR remote sensing to retrieve the mineralogical composition of mineral aerosols will be addressed.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005