An alternative method for aerosol optical thickness retrieval in the UV range

Atmospheric aerosol particle size distribution data derived from almucantar scans performed by the CIMEL sunphotometer at Belsk, Poland, in 2005 are used for the estimation of aerosol optical thickness (AOT) in the UV range by applying the Mie theory. The results obtained are compared with the direct Sun measurement data from the CIMEL sunphotometer and collocated Brewer spectrophotometer No. 064, as well as with AOT obtained by Angström extrapolation from the direct Sun measurements performed by the CIMEL sunphotometer in the visible range of wavelengths. Mean differences between calculated and measured values of AOT are up to about 8% in the UV-B range, which is close to the measurement uncertainty of the Brewer spectrophotometer and much less than that obtained by means of Angstrom extrapolation (over 24% in the UV-B range).