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

A new algorithm to determine both the instantaneous values of the aerosol optical depth tau(alpha lambda) and the daily atmospheric ozone content Oz is presented. The algorithm is based on inversion methods and uses instantaneous 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 estimated by means of this algorithm have been compared with those obtained by the algorithm proposed by Flittner et al. [17] and by an algorithm, based on Flittner but em ploying the covariance matrix associated with the experimental errors in its calculations. Experimental measurements of direct spectral irradiance at normal incidence have been used as input parameters in these algorithms. The error analysis shows that the errors introduced by this method are small. Furthermore, the proposed method has the additional advantage of showing the variations of the aerosol optical depth with the optical air mass.