Dust specific extinction cross-sections over the Eastern Mediterranean using the BSC-DREAM model and sun photometer data: the case of urban environments

In this study, aerosol optical depth (AOD) mea- surements, from a MFR sun photometer operating in Athens, were compared with columnar dust loading estimations, from the BSC-DREAM model, during identified dust events, in order to extract the typical specific extinction cross- section for dust over the area. The selected urban environ- ment of Athens provided us with the opportunity to inves- tigate the mixing of dust and urban pollution and to esti- mate the contribution of the latter. The specific extinction cross-section for dust at 500 nm was found to be equal to 500 =0.64±0.04 m 2 g, typical for medium to large distances from dust sources, with weak wavelength dependence in the visible and near infrared band (0.4-0.9 µm). The model showed a tendency to underpredict AOD levels for increas- ing values of the ˚ Angstr¨