Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 8, 481-489, 2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.
05 Feb 2008
Some considerations about Ångström exponent distributions
F. Wagner1 and A. M. Silva1,2 1Centro de Geofísica, Évora, Portugal
2Universidade de Évora, Departamento de Física, Évora, Portugal
Abstract. A simulation study has been performed in order to show the influence of the aerosol optical depth (AOD) distribution together with the corresponding error distribution on the resulting Ångström exponent (AE) distribution. It will be shown that the Ångström exponent frequency of occurrence distribution is only normal distributed when the relative error at the two wavelengths used for estimation of the Ångström exponent is the same. In all other cases a shift of the maximum of the AE-distribution will occur. It will be demonstrated that the Ångström exponent (or the maximum of an AE distribution) will be systematically over- or underestimated depending on whether the relative error of the shorter wavelength is larger or smaller compared with the relative error of the longer wavelength. In such cases the AE distribution are also skewed.

Citation: Wagner, F. and Silva, A. M.: Some considerations about Ångström exponent distributions, Atmos. Chem. Phys., 8, 481-489,, 2008.
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