A new inversion algorithm to retrieve instantaneous values for the aerosoloptical depth from spectral irradiance measurements

A new algorithm to determine both the instantaneous values of the aerosol o ptical depth tau(alpha lambda) and the daily atmospheric ozone content Oz i s presented. The algorithm is based on inversion methods and uses instantan eous experimental data of the total atmospheric optical depth tau(T lambda) A description of the method and an analysis of the Oz and tau(alpha lambda ) values for clear days in Valencia (Spain) is presented. The values estima ted by means of this algorithm have been compared with those obtained by th e algorithm proposed by Flittner et al. [17] and by an algorithm, based on Flittner but em ploying the covariance matrix associated with the experimen tal errors in its calculations. Experimental measurements of direct spectra l irradiance at normal incidence have been used as input parameters in thes e algorithms. The error analysis shows that the errors introduced by this m ethod are small. Furthermore, the proposed method has the additional advant age of showing the variations of the aerosol optical depth with the optical air mass.