Application of WRF-CMAQ Model System for Analysis of Sulfur and Nitrogen Deposition over Bulgaria.

The advanced air quality modelling system WRF-CMAQ is applied to estimate the spatial distribution of sulfur and nitrogen wet deposition on seasonal basis for 2016 and 2017. The numerical system is set-up for nested domains, from European scale (d1-81 km resolution) to country level (d3-9 km resolution) to account for transport and chemistry processes taking place over broad range of scales and impacting the deposition at given location. A precipitation bias adjustment approach is applied to all grid nodes of domain d3 in order to reduce effects of precipitation overestimation by the model. The effect of the bias adjustment on the seasonal deposition pattern is discussed. The approach leads to 25% decrease in annual wet depositions for the country.