Direct Climatic Effect of Aerosols and Interdecadal Variations over East Asia Investigated by a Regional Coupled Climate-Chemistry/Aerosol Model

Abstract

The direct climatic effect of aerosols for the 1980–2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/aerosol model, which includes major anthropogenic aerosols (sulfate, black carbon, and organic carbon) and natural aerosols (soil dust and sea salt). Anthropogenic emissions used in model simulation are from a global emission inventory prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5), whereas natural aerosols are calculated online in the model. The simulated 20-year average direct solar radiative effect due to aerosols at the surface was estimated to be in a range of −9– −33 W m-2 over most areas of China, with maxima over the Gobi desert of West China, and −12 W m-2 to −24 W m-2 over the Sichuan Basin, the middle and lower reaches of the Yellow River and the Yangtze River. Aerosols caused surface cooling in most areas of East Asia, with maxima of −0.8°C to −1.6°C over the deserts of West China, the Sichuan Basin, portions of central China, and the middle reaches of the Yangtze River. Aerosols induced a precipitation decrease over almost the entire East China, with maxima of −90 mm/year to −150 mm/year over the Sichuan Basin, the middle reaches of the Yangtze River and the lower reaches of the Yellow River. Interdecadal variation of the climate response to the aerosol direct radiative effect is evident, indicating larger decrease in surface air temperature and stronger perturbation to precipitation in the 1990s than that in the 1980s, which could be due to the interdecadal variation of anthropogenic emissions.