LASGη坐标有限区域数值预报模式对一次登陆台风特大暴雨的数值试验  

A Numerical Simulation of an Extraordinary Storm Rainfall Caused by a Landing Typhoon with LASG Mesoscale Model

作　　者：蔡则怡[1] 宇如聪[1] 

机构地区：[1]中国科学院大气物理研究所

出　　处：《大气科学》1997年第4期459-470,共12页Chinese Journal of Atmospheric Sciences

基　　金："八五"国家重点科技攻关课题;国家自然科学基金

摘　　要：本文用ＬＡＳＧη坐标有限区域数值预报模式，对１９７５年８月河南地区登陆台风特大暴雨进行了数值试验。这次暴雨有很强的局地性，主要表现在水文站的雨量极值远超过气象站的最大雨量值，为３～１６倍。一般有限区域数值预报模式预报的雨量都比气象站的最大雨量值小。与水文站的雨量极值相差更远。ＬＡＳＧη坐标有限区域数值预报模式考虑了我国复杂的地形作用，具有能量和质量守恒的动力框架，考虑了与降水有关的主要物理过程。用该模式对著名的“７５·８”特大暴雨５～７日３天３次暴雨作了２４小时数值试验，取得了较好的预报结果：其预报最大雨量为气象站的最大雨量值的１～５倍，达水文站的雨量极值的３４％～４９％，为模式网格面积平均的最大深度的５４％～９８％。预报最大雨量中心位置偏离气象站雨量中心的距离约为０．６７～１．４７个网格距，偏离雨量极值的水文站的距离为０．２３～１．０７个网格距。这３次特大暴雨的强度、位置和其变化趋势的预报都与实况相近。同时，模式对暴雨系统和大尺度形势的预报也都与实况基本一致。该模式之所以对这种局地性很强的突发性特大暴雨有较好的预报能力，是由于它有较强的地形处理能力。还有，由控制试验和４种地形敏感性试验的结果可见，山脉的相?The numerical simulation of the extraordinary storm rainfall during August 1975 in Henan Province is investigated by the LASG η-coordinate limited-area mesoscale model (LASG η MM). The precipitation in this event is very localized and the distribution over the whole area is not uniform. The 24-hour extremum rainfall recorded by the hydrological stations which are more densely distributed in this area is about 3～16 times of the maximum rainfall. Generally, the rainfall calculated by the limited- area numerical models is less than the observation by meteorological stations and much less than that by hydrological stations. The LASG η MM is characterized by the η vertical coordinate, which is suitable to the complicated topography of China. The basic equations in this model are the dynamic structure with the perfect energy and mass conservation and include all main physical processes of the precipitation. For this well-known extraordinarily storm rainfalls during August 5～7, 1975, the maximum rainfalls predicted by the LASG η MM are about, 1～5 times of that observed by the meteorological stations, 34%～49% of that observed by the hydrological stations, and 54%～98% of the maximum depth averaged over areas corresponding to the model grid size. The deviations of the location of the predicted rainfall centers are 0.67～1.47 and 0.23～1.07 grid size compared with the observational results by meteorological stations and by the hydrological stations respectively during these three days. The forecast results for the weather system with the storm rainfall and the large scale systems by the LASG η MM are also very similar to by the two kinds of stations. The further experiments of effect of topography show that the maximum precipitation is highly sensitive to the relative height and slope of the mountain, and relative positions of the storm rainfall weather system and the mountain. A small change in the topography will result in a great change in the 24-hour maximum precipitation.

关 键 词：台风 暴雨 Η坐标 地形影响 数值预报模式 

分 类 号：P457.6[天文地球—大气科学及气象学] P457.8