【摘要】 利用地面区域站降水量资料、NCEP FNL再分析资料、风云卫星数据产品以及WRF数值模拟结果,对2013年7月7~9日发生在西北地区东部的一次暴雨过程进行诊断分析。结果表明:此次暴雨是一次典型的副热带高压(简称副高)西北侧西南气流型暴雨,西风槽和高原槽发展东移,配合副高外围的西南气流及低层低涡切变是造成此次暴雨的主要影响系统。高低空急流的耦合、充沛的水汽聚集、较强的动力作用以及大气层结的不稳定等对此次强降水的发展起到促进作用。WRF模式对此次复杂地形下的暴雨有较好的模拟能力,模拟的降水与实况相吻合,风场、比湿、涡度、CAPE、垂直速度等物理量对此次降水过程有较好的反映。低层气流经喇叭口地形时被抬升并辐合,再配合丰富的水汽场,使得降雨过程得以维持和发展。更多还原

【Abstract】 Based on the hourly precipitation from weather stations,NCEP FNL reanalysis data with 0. 1° × 0. 1° resolution,products of FY- 2E satellite and output results from Weather Research and Forecasting Model( WRF),the heavy rainfall from 7 to 9 July 2013 in east of northwest China was diagnosed. The results showed that the rainstorm was a typical southwesterly airflow rainfall process which located in northwest of subtropical high system. The development and movement of the westerly trough and plateau trough,cooperating with the southwesterly airflow and the vortex shear line in low level,were main influence systems of heavy rainfall. The coupling of upper and lower jets,the abundant water vapor together,the stronger dynamic effect and the instable atmospheric stratification facilitated the development of the heavy rainfall. The hourly evolution of TBB from FY- 2E was consistent with that of rainfall intensity,when the rainfall increased dramatically at 14: 00 BST on 8 July 2013,the TBB reduced to below- 45 ℃ in east of northwest China. The model of WRF had a better capacity to simulate the weather process of rainstorm under complicated terrain. The evolution and magnitude of rainfall simulated by WRF from 08: 00 BST 8 to 08: 00 BST 9 July 2013 was similar to the observation,and the centre rainfall located in Qingyang of Gansu Province. The simulated physical quantities of wind field,specific humidity,vorticity,CAPE and vertical velocity could well reflect the process of the heavy rainfall event. The low- level airflows were lifted and converged via the trumpet- shaped topography,which caused the increasing of cyclone and enhancing of vertical motion,cooperated with abundant water vapor,eventually caused the enhancement of heavy rainfall. Therefore,the simulated results by WRF model could be used to analyze the structure of β- scale rainfall system under rough topography,which could fill the lack of observation data.更多还原