Fast Climate Cystem Responses to Different Forcing Agents Based on CMIP5 Atmospheric Models

Abstract:

Herein, fast climate system responses to CO₂, aerosol and sulfate aerosol forces are studied based on simulations of CMIP5 atmospheric models. We demonstrated that the fast climate adjustments caused by CO₂ forcing lead to decreases in global mean cloud fractions, evaporation and precipitation, and to increases in the net radiative forcing and atmospheric water vapor content. The inhibition of rainfall is primarily contributed from the reduced oceanic precipitation. Regionally, Africa, South Asia, East Asia and Australia exhibit pronounced increases in rainfall, which are presumably attributed to the strengthened summer monsoon caused by the increased land-sea thermal contrast. Aerosol and sulfate forcing exhibit only a slight effect on the global hydrological cycle before global surface temperature changes. However, by affecting the land-sea thermal contrast, they can have profound effects on regional-scale hydrological cycles, such as those over southern Africa, South Asia and East Asia in the boreal summer. Moreover, the cloud fast feedback under the aerosol forcing is highly associated with the way of dealing with aerosols in the atmospheric model.