Process Analysis of Atmospheric Composition Fields in Urban Area (Sofia City)

The air pollution pattern is formed as a result of interaction of different processes, so knowing the contribution of each one of the processes for different meteorological conditions and given emission spatial configuration and temporal profiles could be helpful for understanding the atmospheric composition and air pollutants behavior. Analysis of the contribution of these different processes (chemical and dynamical) which form the atmospheric composition in chosen region will be demonstrated in the present paper. To analyze the contribution of different dynamic and chemical processes for the air pollution formation over Sofia the CMAQ Integrated Process Rate Analysis option was applied. The procedure allows the concentration change for each compound to be presented as a sum of the contribution of each one of the processes, which determine the air pollution concentration. A statistically robust ensemble of the atmospheric composition over Sofia, taking into account the twoway interactions of local to urban scale and tracking the main pathways and processes, which lead to different scale atmospheric composition formation should be constructed in order to understand the atmospheric composition climate and air pollutants behavior. On the basis of 3D modeling tools an extensive data base was created and this data was used for different studies of the atmospheric composition, carried out with good resolution using up-to-date modeling tools and detailed and reliable input data. All the simulations were based on the US EPA (Environmental Protection Agency) Model-3 system for the 7 years period (2008 to 2014). The modeling system consists of 3 models, meteorological pre-processor, the emission pre-processor SMOKE and Chemical Transport Model (CTM) CMAQ.