云微物理影响东亚污染性沙尘气溶胶跨太平洋传输的数值模拟研究

Dust aerosol has a significant effect on global radiative balance and climate change. Most East Asian dust passes Eastern China and transports over the Pacific. Previous studies indicate that more than half East Asian dust mixes with polluted aerosols during the transport, changing from insoluble to soluble, becoming cloud condensation nuclei (CCN) and easier be removed by cloud processes. In current climate models, simulated trans-Pacific transport of Asian polluted dust is not realistic. The parameterization is highly simplified and has large uncertainties. This study will apply the Lagrangian parcel model to analytically simulate the activation process of polluted dust aerosol, in order to understand the mechanism of rain out removal process and its efficiency dependence on the changing solubility of polluted dust. The parameterization of rain out process in the global climate model CIESM (Community Integrated Earth System Model) will be modified according to the parcel model analysis. The wet removal efficiency will be analytically calculated in climate model for the first time. The improved climate model will be evaluated with the CALIOP satellite data, which is the only dataset providing polluted dust observations. The comparison between model results and satellite data focuses on the climatologically temporal and spatial distribution of dust aerosol over the Pacific. The improved model will also run for the future scenario with IPCC estimated aerosol emission, to simulate the transport and distribution of polluted dust aerosol over the Pacific and predict the dust effects on radiative forcing and climate change.

沙尘气溶胶对全球辐射平衡及气候变化有不可忽视的作用，其中东亚沙尘的一个重要传输路径是途经我国东部跨越太平洋。研究表明，一半以上的东亚沙尘在传输途中会与污染性气溶胶混合，从不可溶变为可溶，更易成为云凝结核，并受雨除过程影响发生湿沉降。当前气候模式中对东亚污染性沙尘跨太平洋传输的模拟效果较差，模拟方法较为简化，且仍有诸多不确定因素。本项目拟采用解析云微物理过程的拉格朗日气团模型，模拟污染性沙尘气溶胶的核化过程，分析可溶性的改变影响雨除效率的具体机理。并依据此机理改进全球气候模式CIESM中的参数化方案，在模式中首次加入污染性沙尘雨除过程的解析模拟。改进后的模式将与当前唯一可观测污染性沙尘的CALIOP卫星数据进行比对评估，重点分析沙尘在太平洋上空的气候态时空分布特征。随后根据IPCC排放清单对未来污染气溶胶的估计情景，模拟东亚污染改善的情况下，污染性沙尘传输与分布的改变对辐射和气候的影响。