Effects of Satellite Data Assimilation in Air Quality Modelling in Bulgaria

The operational Bulgarian Chemical Weather Forecast System (BgCWFS) was modified and applied for assimilation of satellite retrieved atmospheric chemistry parameters—Aerosol Optical Depth (AOD) and columnar values of NO₂ and SO₂. The work outlines the methodology based on calculation of correction factors between model estimated and assimilated satellite derived parameters. Simulations by two versions of the system were performed for two months (August 2017 and February 2019) for all 5 domains of BgCWFS. The first version, mod-run, is without satellite data assimilation, the second one, sat-run assimilates satellite data. The effects of the assimilation is demonstrated for different pollutants analysing the difference between the results of the two versions on particular days in different model domains and as domain mean values for the Balkan Peninsula and for Bulgaria. The domain mean monthly particulate matter concentrations increase by more than 100% in summer and by about 50% in winter. The increase in the domain mean monthly SO₂ concentrations is about 110% in summer and 130% in winter.