Global and Indian precipitation responses to anthropogenic aerosol and carbon dioxide forcings from PDRMIP experiments

Abstract. Global precipitation change in response to climate change is closely related to surface temperature, the forcing agent, and the atmospheric dry energy budget, but regional precipitation change is more complex. In this study, we use experiments from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP) wherein carbon dioxide, sulfate aerosols, and black carbon aerosols are perturbed to study the global precipitation response in contrast with the regional response over India. The response to global warming from carbon dioxide increases precipitation both globally and regionally, whereas the cooling response to sulfate aerosol leads to a reduction in precipitation in both cases. The response to black carbon aerosols, however, is a global decrease but a regional increase of precipitation over India. The mechanism is increased atmospheric heating driving a stronger monsoon circulation and stronger low-level winds. This intensification of the Indian monsoon is, somewhat surprisingly, stronger for global black carbon emissions than when the emissions are limited to those from the Asian region. Overall, our study presents heterogeneity in precipitation responses at both global and regional levels and the potential underlying physical processes under a variety of climate forcings that would be useful in designing further model experiments with higher spatial resolution.