【作者】 李燕；

【导师】 邱崇践；

【作者基本信息】 兰州大学 ， 气象学， 2006， 硕士

【摘要】 中尺度数值模式MM5中有多种积云参数化方案可供选择，不同的参数化方案及分辨率对降水预报有很大影响。本文目的在于通过常用的四种积云参数化方案及嵌套网格方案对辽东半岛暴雨过程进行试验，以研究不同参数化方案和嵌套网格对辽东半岛暴雨模拟的影响。选取2005年7月25日辽东半岛南部及海峡地区的一次大暴雨过程做数值模拟试验。通过比较和分析不同方案的模式输出结果，主要结论归纳如下： 二重嵌套数值模拟结果与客观分析对比发现： 1．MM5模式能够很好地再现辽东半岛大暴雨的大、中尺度环流系统。 2．高空强辐散，低空强辐合及对应的强上升运动和气旋性涡柱的发展是造成此次暴雨的动力机制。 3．低空西南气流以及高空干冷空气侵入对这次暴雨的产生和发展起重要的作用。 积云对流参数化方案一对比分析表明： 1．不同的参数化方案，对强降水落点和降水强度的模拟，结果差别较大。模拟较好的是GR方案，最差的是AK方案。 2．四种积云对流参数化方案模拟的海平面气压场差别较大，其中GR方案较好地模拟出造成这次暴雨的高低压系统和中尺度气旋。 3．粗网格采用一定的积云对流参数化后，可一定程度再现一些中尺度特征。 4．四种方案由于闭合假设不同，模拟的云物理特征存在很大差别，这种差别对各种天气要素的准确预报会产生一定的影响。 积云对流参数化方案二对比分析表明： 1．细网格信息可以通过嵌套边界向外层传递，影响外层预报结果。细网格选取GR方案比选取AK、BM、KF方案模拟效果好很多。 2．细网格参数化方案不变，粗网格取不同的参数化方案，对细网格的模拟结果差别不大。但选取一个好的参数化方案对细网格的模拟结果会稍有改进。 不同嵌套网格模拟试验结果显示： 1．采用多重嵌套网格模拟技术，可有效改善预报的物理场，使得模拟物理场机构更加精细，也更接近大气实况。 2．采用多重嵌套网格模拟技术，由于地形和非线性的作用，模式运行中有可能激发出比较合乎实际的中、小尺度扰动，不仅降水强度、范围模拟较好，而且对造成大暴雨的中尺度气旋也模拟较好。 3．使用嵌套网格后细网格区域能够更真实的描写大气情况，改善模拟结果；细网格的中尺度信息能够通过嵌套边界向外层传递，从而有效改善外层粗网格的模拟结果。 4．通过粗、细网格的相互作用，模式将能更好模拟和预报一些中、小尺度现象。由分析可推测此次过程是中小尺度共同影响造成的。更多还原

【Abstract】 There are kinds of cumulus parameterization schemes (CPSs) in the mesoscale numerical model MM5 can be chosen. Different CPSs and horizontal resolution will produce considerably different influences on the precipitation forecast. The purpose of this paper is to investigate the influences of different parameterization schemes and nesting grid on simulation of LiaoDong Peninsula rainstorm by the trials of four common CPSs and nesting grid on LiaoDong Peninsula rainstorm process. We present a numerical simulation test of a heavy rainstorm process that occurred over the southern LiaoDong Peninsula and the BoHai strait areas at 25th July 2005. By comparing and analyzing the output data of different schemes, the maim results are following:The comparison between the numerical simulative results of dual nesting grid and objective analysis indicates that:1. MM5 model can well reappeared the large scale and mesoscale circumfluence systems of LiaoDong Peninsula heavy rainstorm.2. A coupling of the intense divergence on upper levels and intense convergence on lower levels as well as intensive ascending motion and the cyclonic vorticity column are the dynamic mechanisms for the heavy rainstorm occurrence.3. The southwest airflow on lower levels and the inrush of arid cold air on upper levels play an important rules on the out-growth and development of this rainstorm.The comparison analysis for cumulus convection parameterization scheme No.1 shows:1. Different parameterization schemes have significant difference of the simulative effects on the location of rainfall center and rainfall intensity. The GR scheme was the best, the AK scheme was the worst.2. The simulative sea level pressure of four CPSs showed large difference, in which the GR scheme had better simulated the high, low systems and mesoscale cyclone.3. The coarse-mesh scheme which adopting certain cumulus convection parameterization can reappear some mesoscale characteristics in a certain extent.4. Because of different closure assumptions in four schemes, the simulated cloud physical characteristics have significant difference. This difference will have some effects on the accurate prediction of kinds of weather elements.The comparison analysis for cumulus convection parameterization scheme No.2 shows:1. Fine-mesh messages can be transferred to outer space by nesting border, so that affect the forecast results. Fine-mesh of GR scheme can better simulate than that of AK, BM and KF schemes.2. When fine-mesh parameterization scheme is invariable, different coarse-mesh更多还原