Effects of Anthropogenic Aerosols on Marine Stratocumuli over Southeast Pacific

Off the coast of Chile, there exists an extensive and persistent stratocumulus deck formed by large-scale cold SSTs with warm and dry air aloft. The anthropogenic aerosols transport from land to sea, may affect cloud properties and change solar and longwave radiation reaching the surface. Here, we conduct a model study together with the data from 2008 VOCALS campaign, to evaluate the effects of anthropogenic aerosols on marine stratocumuli over Southeast Pacific. Simulations from a version of WRF model that has incorporated a statistical-numerical two-moment cloud scheme were analyzed and compared with observations. Results show that the model captures the observed features of cloud fraction and depth, boundary layer structure and microphysical properties of stratocumuli. It is also found that, while the large-scale meteorology dominates the cloud macrophysical features, anthropogenic aerosols can increase the droplet numbers and decrease their sizes yielding an enhancement of cloud albedo. Further analyses of the effects of changes in cloud properties on the surface radiation balance will be presented.