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| Titel |
Absorption Angstrom Exponent in AERONET and related data as an indicator of aerosol composition |
| VerfasserIn |
P. B. Russell, R. W. Bergstrom, Y. Shinozuka, A. D. Clarke, P. F. DeCarlo, J. L. Jimenez, J. M. Livingston, J. Redemann, O. Dubovik, A. Strawa |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 3 ; Nr. 10, no. 3 (2010-02-03), S.1155-1169 |
| Datensatznummer |
250008035
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| Publikation (Nr.) |
 copernicus.org/acp-10-1155-2010.pdf |
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| Zusammenfassung |
| Recent results from diverse air, ground, and laboratory studies using both
radiometric and in situ techniques show that the fractions of black carbon,
organic matter, and mineral dust in atmospheric aerosols determine the
wavelength dependence of absorption (often expressed as Absorption Angstrom
Exponent, or AAE). Taken together, these results hold promise of improving
information on aerosol composition from remote measurements. The main
purpose of this paper is to show that AAE values for an Aerosol Robotic
Network (AERONET) set of retrievals from Sun-sky measurements describing
full aerosol vertical columns are also strongly correlated with aerosol
composition or type. In particular, we find AAE values near 1 (the
theoretical value for black carbon) for AERONET-measured aerosol columns
dominated by urban-industrial aerosol, larger AAE values for biomass burning
aerosols, and the largest AAE values for Sahara dust aerosols. These AERONET
results are consistent with results from other, very different, techniques,
including solar flux-aerosol optical depth (AOD) analyses and airborne in
situ analyses examined in this paper, as well as many other previous
results. Ambiguities in aerosol composition or mixtures thereof, resulting
from intermediate AAE values, can be reduced via cluster analyses that
supplement AAE with other variables, for example Extinction Angstrom
Exponent (EAE), which is an indicator of particle size. Together with
previous results, these results strengthen prospects for determining aerosol
composition from space, for example using the Glory Aerosol Polarimetry
Sensor (APS), which seeks to provide retrievals of multiwavelength
single-scattering albedo (SSA) and aerosol optical depth (and therefore
aerosol absorption optical depth (AAOD) and AAE), as well as shape and other
aerosol properties. Multidimensional cluster analyses promise additional
information content, for example by using the Ozone Monitoring Instrument
(OMI) to add AAOD in the near ultraviolet and CALIPSO aerosol layer heights
to reduce height-absorption ambiguity. |
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