同化雷达估算降水率对暴雨预报的影响  

Effects of Assimilating Radar Rainfall Rate Estimation on Torrential Rain Forecast

作　　者：高郁东[1,2] 万齐林[1,2] 薛纪善[1,2,3] 丁伟钰[1,2] 李昊睿[1,2] 张诚忠[1,2] 黄燕燕[1,2] 

机构地区：[1]区域数值天气预报重点实验室,广州510080 [2]中国气象局广州热带海洋气象研究所,广州510080 [3]中国气象科学研究院,北京100081

出　　处：《应用气象学报》2015年第1期45-56,共12页Journal of Applied Meteorological Science

基　　金：国家自然科学基金项目(41475102);公益性行业(气象)科研专项(GYHY201006016);广东省气象局科学技术研究项目(2013Q02)

摘　　要：选取2009年3月28日广东省广州市大暴雨过程,考察了变分校准前后Z-I关系估算雷达降水率的区别。变分校准后的降水率资料具有较高的单点精度与合理的梯度分布。降水率资料能够反映大气动力特征和水汽分布等重要信息,是模拟中小尺度系统的关键因子。基于GRAPES(Global/Regional Analysis and Prediction System)区域三维变分系统,将FSU(Florida State University)对流参数化方案作为观测算子的同化试验指出,同化降水率资料后同时增强了低层大气的辐合和高层大气的辐散,从而使整层气柱的不稳定能量增加。沙氏指数和K指数诊断分析也表明,同化降水率资料后有利于触发强对流天气。此外,低空辐合有利于水汽垂直输送,维持对流发展,改进降水模拟。逐小时数值模拟结果表明:同化校准后的雷达估算降水率不仅可以改进降水分布,而且使中尺度对流系统的发展和消亡清晰地表现出来。Meso-scale weather system, such as torrential rain, is neither easily detected nor effectively simulated. Main causes consist of the insufficient observation and the inaccurate initial filed, which are prepared for the routine weather prediction and the hazardous weather simulation. To solve these problems, high resolution rainfall rate data estimated by doppler radar Z-I relationship is calibrated with AWS data by variational method. The forecast experiment on a torrential rain case captured by the radar in Guangzhou indi- cates that the east center of precipitation omitted in the original Z-I estimation is forecasted after the calibration. Even though the minor amount of rainfall rate is inclined to be overestimated, relative errors of calibration significantly decline as the increase of rain rate value. As a result, high resolution datasets of calibration rain rate are demonstrated to possess a more accurate single point value than the estimation of Z-I relationship and a more reasonable gradient than AWS data. Meanwhile, according to the distribution of instantaneous precipitation, calibration rainfall rate datasets imply lots of information on the atmospheric dynamic and moisture, which are the maior factors to arouse a convective rainstorm. To verify various advantages of mixed characteristics, a set of experiments are performed using FSU （Florida State University） cumulus parameterization scheme as the observational operator, based on GRAPES （Global/Regional Analysis and Prediction System） Regional Three Dimensional Variation Sys- tem. Compared with NCEP （National Centers for Environmental Prediction） global analysis data, the convergence in lower level and the divergence in higher level after assimilation are conspicuously strengthened, which sequentially lead the unstable energy in atmosphere to be elevated. Showalter index and K index di- agnose indicate a heavy rain in the dense data region as well. In addition, the vertical transportation of moisture forced by the convergence sustains a s

关 键 词：暴雨 校准雷达估算降水率 降水率同化 数值预报 

分 类 号：P457.6[天文地球—大气科学及气象学] P412.25