Aerosol type influences on air and climate over the temperate areas

Aerosols significantly affect air and climate in various ways. The present study focuses on examining the column-integrated aerosol optical characteristics such as aerosol optical depth, Angstrom exponent, particle size distribution and radiative forcing based on AERONET/PHOTONS ground measurements for thirty sites classified in five zones: Mediterranean, maritime, humid subtropical, continental and desert and high urban zone, distributed over the temperate areas. The annual mean aerosol optical depth AOD 0.5 seems uniform close to 0.15 ± 0.017 for the Mediterranean, maritime and humid subtropical zona. It reaches the maximum 0.62 at the high urban zone and especially South Asian sites where it coincides with a significant increase of both fine and coarse mode volume concentrations and non-quite visibility. Angstrom exponent (α 0.44–0.87 ) versus AOD 0.5 show the dominance of mixed type with (~ 40.26%) and the biomass burning and urban/industrial aerosols (~ 24.89%) for the high urban zone in agreement with the corresponding single-scattering albedo, and complex refractive index data. The highest AOD s induces the highest radiative forcing at the earth’s surface, mainly at the South Asian sites. At the large urban zone, the forcing quantification reflects a very significant contribution of heat at the level of the atmospheric column that induces severe internal climatic variability in the direction of regional and then global warming.