Air Pollution in Eastern Mediterranean: Nested-Grid GEOS-CHEM Model Results and Airborne Observations

Trace gases concentrations in the boundary layer (BL) and the free troposphere are studied in the Eastern Mediterranean based on an updated nested-grid application of GEOS-CHEM global model and airborne observations that were collected over the Greek territory during the AEGEAN GAME airborne field campaign in September 2011. Modelled concentrations are studied against measurements along the flight tracks. Moreover, the spatial distribution of the pollutants over the study domain is examined in relation to the prevailing wind regime. The role of the long-range transport of pollution is investigated particularly through the northern and eastern boundaries due to the prevailing NE circulation. It is found that the model captures adequately carbon monoxide (CO) and ozone (O3) levels within the troposphere. CO and O3 concentrations over the Aegean Sea can exceed the background levels attributed either to transport downwind the local sources or to long range transport particularly from the northern and eastern part of the domain under the strong NE Etesian winds.