资源环境科技发展态势分析平台

The instantaneous direct radiative forcing is a basis for estimating the aerosol's climate effect, which is still one of the most uncertain factors. In this study, we incorporate eight minerals into a dust emission model that is coupled with the regional model. The model is used to estimate the direct radiative impact at the top of the atmosphere and at the surface by mineral dust. In addition, multiple tests are performed to investigate the sensitivity of the forcing to some key parameters (such as the surface albedo and key minerals, e.g., hematite and calcite). Based on our simulations of a dust event in Central Asia, the net instantaneous direct forcing (solar + infrared), averaged over the Aral Sea basin on 7 May 2007, are approximately in a range of(-8.05,-0.47)>W/m(2) at the top of the atmosphere. In comparison to the forcing estimated based on the default complex index, incorporation of dust minerals introduced a less cooling effect at the top of the atmosphere. We found that for a given clay-to-silt ratio, the net instantaneous forcing and the forcing in the solar band are sensitive to the surface albedo and hematite variation in the silt fraction. The forcing in the infrared band, however, is insensitive to these parameters, but it is sensitive to calcite and quartz in the silt fraction. Our results highlight the importance of accurately predicting the size-resolved content of hematite and the surface albedo change to quantify the radiative forcing of mineral dust.