Impact of Stratospheric Aerosol Injection Geoengineering on the Summer Climate Over East Asia

摘要

As a potential approach to counteract global warming, geoengineering has attracted much attention in recent years. We investigate the impacts of stratospheric aerosol injection (SAI) geoengineering on summer (June-August, JJA) temperature and precipitation over East Asia as well as the East Asian summer monsoon (EASM) by using model outputs archived in the G4 stratospheric aerosol injection experiments of the Geoengineering Model Intercomparison Project (GeoMIP). In the G4 experiment, injected sulfate aerosols cause decreases in top-of-atmosphere radiative forcing, surface air temperature, and precipitation, and changes in the EASM and drought/flood pattern in summer over East Asia. The SAI-induced temperature changes show consistent cooling with strong magnitudes over the East Asian continent, while the precipitation and EASM changes vary among regions and models. SAI leads to anomalous anticyclones in the lower troposphere, mainly due to the strong cooling in the middle-to-upper troposphere. The thermodynamic and dynamic mechanisms of SAI-induced summer precipitation change over East Asia are analyzed through the moisture budget equation. The results show that the spatial pattern of precipitation change is dominated by a dynamic divergent component under SAI forcing, indicating the leading role of atmospheric circulation change. This change is closely associated with anomalous cyclones and anticyclones in the lower troposphere.