Actions for Statistical Estimation of the Atmospheric Aerosol Absorption Coefficient Based on the Data of Optical Measurements [electronic resource].

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Statistical Estimation of the Atmospheric Aerosol Absorption Coefficient Based on the Data of Optical Measurements [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy, 2005.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
10 pages : digital, PDF file
Additional Creators
United States. Department of Energy and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
The problem of the choice of the aerosol optical constants and, in particular, imaginary part of the refractive index of particles in visible and infrared (IR) wavelength ranges is very important for calculation of the global albedo of the atmosphere in climatic models. The available models of the aerosol optical constants obtained for the prescribed chemical composition of particles (see, for example, Ivlev et al. 1973; Ivlev 1982; Volz 1972), often are far from real aerosol. It is shown in (Krekov et al. 1982) that model estimates of the optical characteristics of the atmosphere depending on the correctness of real and imaginary parts of the aerosol complex refractive index can differ by some hundreds percent. It is known that the aerosol extinction coefficient α(λ) obtained from measurements on a long horizontal path can be represented as α(λ)=σ(λ)+β(λ), where σ is the directed light scattering coefficient, and β is the aerosol absorption coefficient. The coefficient σ(λ) is measured by means of a nephelometer. Seemingly, if measure the values α(λ) and σ(λ), it is easy to determine the value β(λ). However, in practice it is almost impossible for a number of reasons. Firstly, the real values α(λ) and σ(λ) are very close to each other, and the estimate of the parameter β(λ) is concealed by the errors of measurements. Secondly, the aerosol optical characteristics on the long path and in the local volume of nephelometer can be different, that also leads to the errors in estimating β(λ). Besides, there are serious difficulties in performing spectral measurements of σ(λ) in infrared wavelength range. Taking into account these circumstances, in this paper we consider the statistical technique, which makes it possible to estimate the absorption coefficient of real aerosol on the basis of analysis of simultaneous measurements of the spectral aerosol extinction coefficients α(λ), the directed scattering coefficient of dry aerosol σ₀(0.55) and the mass concentration of aerosol containing BC (black carbon) Ms.
Report Numbers
E 1.99:841497
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Published through SciTech Connect.
03/18/2005.
Fifteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting, Daytona Beach, FL (US), 03/14/2005--03/18/2005.
Kozlov, V.S.; Panchenko, M.V.; Terpugova, S.A.; Uzhegov, V.N.; Pkhalagov, Yu.A.; Pol'kin, V.V.; Shmargunov, V.P.; Yausheva, E.P.
Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk (RU)
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