Impacts of interactive dust and its direct radiative forcing on interannual variations of temperature and precipitation in winter over East Asia

We used two 150 year preindustrial simulations of the Community Earth System Model, one with interactive dust and the other with prescribed dust, to quantify the impacts of changes in wind during East Asian winter monsoon (EAWM) season on dust emissions, and the resulting consequences for interannual variations of temperature and precipitation over East Asia. The simulated December-January-February dust column burden and dust optical depth are lower over northern China in the strongest EAWM years than those of the weakest years by 38.3% and 37.2%, respectively. The decrease in dust over the dust source regions and the downwind region leads to an increase in direct radiative forcing (RF) at the surface by up to 1.5 W m(-2). The effects of EAWM-related variations in surface winds, precipitation, and their effects on dust emissions and wet removal contribute 67% to the total dust-induced variations of direct RF at the surface and partly offset the cooling that occurs with the EAWM strengthening by heating the surface. The variations of surface air temperature induced by the changes in wind and dust emissions between the strongest and weakest EAWM years (strongest minus weakest) decrease by 0.4-0.6 K from eastern coastal China to Japan, which weakens the impact of EAWM on surface air temperature by 3-18% in these regions. The warming results from the combined effects of changes in direct RF, turbulent heat flux at the surface, and northwesterly wind anomalies that bring cold and dry air from Siberia to these regions. Over eastern coastal China, the variations of large-scale precipitation induced by the feedback of EAWM-related changes in wind on dust emissions decrease by 10-30% in winter because of the reduced changes in surface air temperature and the anomalous circulation.