A model study on aerosol impact on extreme precipitation

Observations and model results show an increase in extreme precipitation with global warming since the 1950s. During the last decades there have also been strong trends in anthropogenic aerosol concentration, aerosols that may affect cloud and precipitation processes that develop these extreme events. As human activities are the source of anthropogenic aerosols, they tend to be concentrated over highly populated regions where the potential cost and impact of extreme precipitation is high. In this study we investigate the link between extreme precipitation and aerosol particles in the atmosphere by using the cloud resolving WRF model. The model is set up with an aerosol-dependent cloud microphysics scheme that include processes such as; the increase in smaller droplets in aerosol rich clouds, the change in cloud reflective properties that can reduce surface evapotranspiration as well as a deepening of convective clouds and possible an increase in precipitation intensity. The model is run over several years in a stable climate to distinguish how these processes influence extreme precipitation separately from the extreme precipitation increase due to global warming.