Radiative forcing due to sulfate aerosols in Europe

Climate effects due to the increasing burden of manmade aerosols are expected to countarct the warming effects due to increasing levels of greenhouse gases by a significant part. Here, we consider the direct effects of sulfate aerosols. The atmospheric lifetime of these aerosols is in the order of a week, depending on meteorological conditions. Hence, their concentratíons show a large variability in space and time. Sulfur emissions lead to the formation of sulfate aerosols. These particles are capable of reflecting solar radiation. In addition to this direct efiect, aerosols may alter the size distribution of cloud droplets and hence the reflectivity of clouds. The total aerosol efiect is not well-known. Uncertainties are largely associeted with estimates of the emissions of the precursors snd with the parameterizations of chemical processes as well as the modelled transports. In addition, uncertainties in the microphysical properties, such as seize distribution and the interactions of aerosols with water vapour and droplets, hamper accurate estimates of the radiative effect