The focus of present paper is upon aerosol variability in Bucharest metropolitan area and its relationships with aerosol direct effect/forcing (DRE/DRF). The aerosol (particulate matter less than 10 mu m, PM10) mass concentrations were collected at three sampling sites (within a grid-scale of a regional climate model) covering three types of pollution (urban, suburban, and rural) in Bucharest area during 1st of June 2014 to 31st of May 2015. The aerosol optical properties were computed using the Optical Properties of Aerosol and Clouds (OPAC) software package, based on Mie scattering theory. We observed relatively high levels of PM10 with moderate to low seasonal cycle. DRF values indicate a cooling aerosol effect and show annual variations due to the combined effects of variability of aerosol optical properties over Bucharest region and of local geophysical variables. A section dedicated to comparison of aerosol DRF and its efficiency in Bucharest area and worldwide is included.
