非结构网格空气质量模式对东亚强沙尘暴的初步模拟研究

A Preliminary Simulation Study of an East Asian Super Dust Storm by Unstructured Mesh Air Quality Model

基于中国科学院大气物理研究所自主研发的嵌套网格空气质量数值预报模式（NAQPMS）和英国帝国理工学院应用计算与建模小组（AMCG）研制的有限元流体模式（Fluidity）,构建了非结构网格沙尘传输模式（Fluidity-Dust）,并模拟再现了2010年3月19-22日东亚强沙尘暴整个暴发、演变的三维立体动态过程,从整体上对这次沙尘事件有了全新的直观认识和了解。通过利用FY-2D卫星沙尘反演资料及MODIS（Moderate Resolution Imaging Spectroradiometer）卫星反演的气溶胶光学厚度（AOD）资料,可对模拟结果进行整体上对比验证;同时,利用中国9个城市站点的PM10（空气动力学当量直径小于等于10μm的颗粒物,即可吸入颗粒物）地面观测资料以及日本多个站点的激光雷达资料,逐一对比分析了不同地区PM10的时空分布以及沙尘传输经过时的垂直分布情况;并与NAQPMS模式的沙尘模拟结果进行了模式间的对比分析。对比结果均表明：该模式具有较好的模拟能力,能很好地模拟再现整个沙尘暴过程,为今后进一步运用自适应变网格技术以实现对沙尘暴的高精度追踪模拟奠定了基础。不同模式比较是量化模拟不确定性的重要方法。以往沙尘输送模式比较研究表明：起沙量模拟的不确定性是沙尘暴数值模拟的最大不确定来源。本文通过两个具有相同起沙方案的模式对同一沙尘事件的模拟,发现不同的平流方案以及不同的沉降计算也会对沙尘过程模拟产生重要影响。

Based on the Nested Air Quality Prediction Model System（NAQPMS） developed by the Institute of Atmospheric Physics, Chinese Academy of Sciences（IAP/CAS） and the finite element fluid model（Fluidity） designed by the Applied Modeling and Computation Group, Imperial College of London（AMCG/ICL）, an unstructured mesh dust transport model（Fluidity-Dust） has been constructed and employed to simulate and reproduce the outbreak of the Asian super dust storm during 19-22 March 2010 and the evolution of the three-dimensional dynamic process involved in this super dust storm. Results of this study provided new intuitive knowledge and understanding of the dust storm event. The FY-2D satellite dust images and the MODIS（Moderate Resolution Imaging Spectroradiometer） observations of AOD（Aerosol Optical Depth） were used to compare with the simulation results on the whole. To investigate the spatial and temporal distributions of PM10 at different areas, the modeled results were compared with surface PM10 observations at nine Chinese cites, while Japanese lidar measurements were used to evaluate the vertical dust profiles when the dust storm passed by the monitoring sites. Model results have also been compared with the corresponding results of NAQPMS. The comparative analysis showed that the model performed well and could realistically reproduce the evolution of the dust storm. This study laid a foundation for further application of the adaptive mesh technology in real-time tracking simulation of sandstorms in the future. The comparison of different models is an important method to quantify uncertainties in the simulations. Comparative analysis of dust-transport models indicated that the uncertainty in dust flux simulation is the largest source of uncertainty in the numerical simulation of dust storms. We applied these two models that use the same dust deflation module to simulate the same dust event. Results show that different advection schemes and different calculation of deposition have significant impacts on the simulation of the dust storm.