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, doi:10.5194/acp-8-481-2008, 2008.