HR: 15:20h
AN: A13F-07 INVITED    [Abstracts]
TI: The spectral absorption by aerosols from 350-2500nm and its radiative forcing implications
AU: * Martins, J V
EM: martins@umbc.edu
AF: Department of Physics, University of Maryland Baltimore County, 1000, Hiltop Circle, Baltimore, MD 21250, United States
AU: * Martins, J V
EM: martins@umbc.edu
AF: NASA Goddard Space Flight Center, Code 613.2, building 33, room C323, Greenbelt, MD 20771, United States
AU: Chaudhry, Z
EM: zahra@atmos.umd.edu
AF: Department of Atmospheric and Oceanic Science, University of Maryland, 2107 - Computer and Space Science Building, College Park, MD 20742, United States
AU: Artaxo, P
EM: artaxo@if.usp.br
AF: Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, 187, Sao Paulo, SP 05508-900, Brazil
AB: The absorption properties of aerosol particles are still one of the largest uncertainties on the aerosol forcing of the Climate. Global measurements of BC are not available and badly needed. In situ aerosol absorption measurements are often inaccurate, neglect some important properties, and usually cover a narrow spectral range missing significant absorption features. This work presents results of spectral measurements of aerosol absorption efficiency in a broad spectral range (350-2500nm) highlighting some characteristics of BC and other aerosol absorbers. Implications of these results on the aerosol radiative forcing over different surface types will also be discussed. It is well known that BC is the main absorbing material in atmospheric aerosol but it is not the only one. Soil dust absorbs light in the UV and visible, some organic materials absorb in the UV, and there are recent evidences that some organic materials may also absorb light in longer wavelengths. The absorption spectral dependence by aerosol particles is directly influenced by the chemical composition (refractive indices), the relative size of the absorbers versus the wavelength, and by mixtures between the absorbing and non-absorbing materials. Our spectral absorption measurements covering a broad spectral range (350-2500nm) produce enough information to separate these effects determining the absorption contribution by the different aerosol constituents and the identifying the potential mixture between fine and coarse particles. Results from spectral absorption measurements will be presented for Brazil (Sao Paulo and the Amazon), Mexico, China, UAE, Israel, Bodele, and the US. These results were used on radiative forcing calculations for these aerosols and on the determination of their potential to heat the atmospheric column and affect cloud formation and cloud life time. Our calculations show that in many circumstances, the often neglected wide spectral range, and the absorption by coarse mode particles are essential for an accurate determination of the aerosol forcing.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0360 Radiation: transmission and scattering
DE: 3359 Radiative processes
DE: 4801 Aerosols (0305, 4906)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting