During the life cycle of Typhoon Prapiroon in August 2000, a torrential rain occurred in its peripheral areas, and the 24 hours rainfall at the rain center reached 800 mm. The torrential rain is simulated by using a nonhydrostatic mesoscale model (ARPS(V5.2)), and by employing the triply single-way nested-grids. The centers of nested Domain1, Domain2, and Domain3 are at (27.5°N, 117.5°E), (31.5°N, 119.5°E), and (33.5°N, 119.5°E), their grid lengths 45 km, 15 km, and 5 km, and their total grid points 75×75, 140×140, and 180×180, respectively. With the ADAS 3-D data assimilation system, the NCEP/NCAR reanalysis data of 1°×1°, radar echoes and GMS-5 satellite images are assimilated into the ARPS to simulate the torrential rain event. Simple ice phase scheme, Kain and Fritsch cumulus parameterization scheme are used. There are 35 layers in the vertical direction, and the vertical grid distance is 625 m. The integration is performed for 48 hours from 08:00 BST 29 to 08:00 BST 31. The results are analyzed, and compared with radar echoes, GMS-5 satellite images and surface intensive observations. Results show that the meso-scale heavy rain area between the 500 hPa trough and the subtropical high in the left-front of Prapiroon is well simulated by ARPS, and the simulated precipitation area and rainfall center are rather consistent with the observations. The contrast analyses of radar echoes observed and simulated with hydrometeors in the model atmosphere reveals the evolution of MβCS, and four convective belts converge over the vicinity of Xiangshui, and the comparison of simulated and observed skew T-lgp diagrams further exhibits the instability in the torrential rain process. The persistent vertical wind shear provides kinetic energy for development of mesoscale convective systems, therefore is beneficial to the slantwise development of convection cells, and to the occurrence of heavy rain at a fixed point. Considering the similarity of model results and observations, the results of simulation can be used as the base of further research on the torrential rain process.%在2000年12号台风(Prapiroon)影响期间,其外围对淮河流域东北部造成了一次罕见的特大暴雨,暴雨中心响水24 h降水量达到800 mm.文中所用的模式是俄克拉荷马大学风暴分析和预测中心研制的一个三维非静力可压缩数值区域预报模式ARPS(V5.2).采用了3层单向嵌套网格,Domain1中心取为(27.5°N,117.5°E),格距45 km,格点数为75×75;Domain2中心取为(31.5°N,119.5°E),格距15 km,格点数为140×140;Domain3中心取为(33.5°N,119.5°E),格距5 km,格点数为180×180;垂直方向分为35层,垂直格距为625 m.所利用的资料为:2000年8月29-31日每日4个时次(00、06、12、18时) 1°×1°的NCEP/ NCAR再分析资料及713雷达资料、GMS-5红外云图、探空报、地面加密资料.物理过程选用简单冰相方案,Kain和Fritsch 积云参数化方案.对逐时的卫星云图、713雷达图像进行数值反演,结合探空资料反演出暴雨中深对流系统的水汽三维分布情况,通过三维同化系统ADAS处理,同化初始场和侧边界条件,再用ARPS模式进行数值积分,从8月29日08时开始到31日08 时结束,积分48 h.并结合雷达资料、红外云图、探空报、地面加密资料等对数值模拟结果进行了对比分析.结果表明:ARPS较好地模拟了在台风移动的左前方、在高空槽与副高之间出现的中尺度强暴雨区,模拟降水区及暴雨中心位置与实况较为一致.利用模拟大气中的水物质模拟了雷达回波,与实际雷达回波进行了对比分析,揭示了该过程中β中尺度对流系统的演变特征,4条对流带的交汇点在响水附近.并将模式模拟的T-lgp图与实际T-lgp图进行了对比分析,揭示了该次暴雨过程的不稳定性.持续的高空风垂直切变为对流系统的发展提供动能,造成对流系统斜压发展,有利于降水集中在某一固定的地点.由于模拟结果与实况较为接近,因此可以利用模拟结果作为对该暴雨过程作进一步研究的基础.
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