Regional impacts of anthropogenic aerosols on precipitation scaling patterns in representative concentration pathways

Pattern scaling is a useful way to investigate the impacts of global warming with a very wide range of emission scenarios. This approach assumes that the spatial response pattern to global warming (scaling pattern) is common between emission scenarios. However, previous research has shown that the sensitivity of precipitation to global warming has a robust emission-scenario dependency (ESD) because of the ESD of aerosol emissions. We therefore used representative concentration pathways to investigate the regional impacts of aerosol emissions on precipitation scaling patterns. The ESD of aerosol emissions induced an ESD of net downward surface shortwave radiation on a regional and global scale. An ESD of aerosols over the ocean induced an ESD of downward surface shortwave radiatio, and hence an ESD of evaporation. An ESD of evaporation led to an ESD of precipitation over the same region and downstream regions. Contrariwise, when the ESD of aerosols occurred over land, the ESD of surface shortwave radiation was compensated by an ESD of evaporation as well as an ESD of surface longwave radiation and sensible heat. Consequently the ESD of evaporation was weaker over land than over the ocean, and the ESD of precipitation over land does not tend to be statistically significant. Although aerosol loading scaling patterns were not significantly different, the ESD of precipitation was significant over some regions. The ESD of the southern annular mode and polar amplification caused some of the ESD of precipitation.