Optimal Interpolation of Aeronet Radiometric Network Observations for the Evaluation of the Aerosol Optical Thickness Distribution in the Eastern European Region

The application of the optimal interpolation method to assimilation in the chemical transport model of observational data of the aerosol optical thickness (AOT) that are sparse in space and time is validated. Spatial and temporal correlation functions of errors in the results of the AOT simulated by the GEOS-Chem chemical transport model are obtained assuming negligible error of AOT observations in the AERONET ground-based radiometric network. The optimal interpolation method is applied to the AERONET data using the GEOS-Chem results as a background field for the Eastern European region for 2015–2016. Use of the optimal interpolation method is shown to permit the root-mean-square error of the AOT estimate to be reduced by more than a third in places where there are no AERONET stations as compared to the model results.