利用福建龙岩、漳州、泉州新一代多普勒天气雷达和厦门海沧双偏振雷达探测资料,采用动态地球坐标系下双雷达三维风场反演与拼图技术,基于天气研究和预报模式(Weather Research and Forecasting,WRF)及其资料同化系统,对登陆台风"...利用福建龙岩、漳州、泉州新一代多普勒天气雷达和厦门海沧双偏振雷达探测资料,采用动态地球坐标系下双雷达三维风场反演与拼图技术,基于天气研究和预报模式(Weather Research and Forecasting,WRF)及其资料同化系统,对登陆台风"莫兰蒂"(1614)引起的2016年9月14-15日福建强降水过程进行了双雷达风场反演拼图资料检验及其三维变分同化对强降水精细预报影响的数值试验,结果发现:(1)动态地球坐标系下双雷达反演风场能合理反映实际风场分布状况,其误差相对较小。相较厦门翔安风廓线雷达及厦门探空秒级测风数据,反演风风向(风速)平均绝对误差分别为7.8°(2.6 m/s)及3.4°(1.1 m/s);(2)反演风场水平方向稀疏化对同化及预报结果极为重要,过密的反演风场资料会给同化及预报结果带来负效果。文中采用18、6、2 km 3重嵌套,在3重嵌套区域均进行同化以及仅在2 km区域进行同化两种情况下,均表现为当反演风场资料水平分辨率提高到0.1°时,同化分析及预报的台风环流开始受到负影响;且当反演风场资料水平分辨率越高时,负效果越明显。敏感性试验结果显示,分辨率取0.2°时数值预报效果最好;(3)以美国国家环境预报中心全球预报系统(National Centers for Environmental Prediction/Global Forecast System,NCEP/GFS) 0.5°×0.5°分析场为初值,基于3个不同起报时刻(2016年9月14日14时、20时及15日02时)(北京时,下同)模拟的福建省境内台风内核雨带和螺旋雨带逐时演变、台风路径与强度、逐时降水TS评分和空间相关差异显著,其中14日14时起报试验效果最好;而14日20时起报试验效果最差,这与该试验初始台风大风轴风速明显偏大有关;(4)在上述3个不同起报时刻试验基础上,分别增加双雷达反演风场资料的三维变分同化后,福建境内地面风场和台风内核雨带、螺旋雨带逐时分布、逐时降水TS评分和空间相关�展开更多
A modified hydrometeor classification algorithm （HCA） is developed in this study for Chinese polarimetric radars. This algorithm is based on the U.S. operational HCA. Meanwhile, the methodology of statistics-based o...A modified hydrometeor classification algorithm （HCA） is developed in this study for Chinese polarimetric radars. This algorithm is based on the U.S. operational HCA. Meanwhile, the methodology of statistics-based optimization is proposed including calibration checking, datasets selection, membership functions modification, computation thresholds modification, and effect verification. Zhuhai radar, the first operational polarimetric radar in South China, applies these procedures. The systematic bias of calibration is corrected, the reliability of radar measurements deteriorates when the signal-to-noise ratio is low, and correlation coefficient within the melting layer is usually lower than that of the U.S. WSR-88D radar. Through modification based on statistical analysis of polarimetric variables, the localized HCA especially for Zhuhai is obtained, and it performs well over a one-month test through comparison with sounding and surface observations. The algorithm is then utilized for analysis of a squall line process on 11 May 2014 and is found to provide reasonable details with respect to horizontal and vertical structures, and the HCA results---especially in the mixed rain-hail region--can reflect the life cycle of the squall line. In addition, the kinematic and microphysical processes of cloud evolution and the differences between radar- detected hail and surface observations are also analyzed. The results of this study provide evidence for the improvement of this HCA developed specifically for China.展开更多
利用常规地面和高空观测资料、地基GPS/MET水汽资料、NCEP再分析资料以及多普勒天气雷达和双偏振雷达资料,对2018年1月3—4日和24—28日先后发生在安徽的两次暴雪过程(以下简称"0103"过程和"0124"过程)的环流背景...利用常规地面和高空观测资料、地基GPS/MET水汽资料、NCEP再分析资料以及多普勒天气雷达和双偏振雷达资料,对2018年1月3—4日和24—28日先后发生在安徽的两次暴雪过程(以下简称"0103"过程和"0124"过程)的环流背景与动力、热力、水汽输送条件进行对比分析,探讨两次过程降水相态转变过程中大气温度变化的异同。结果表明:(1)两次过程都发生在500 h Pa高空槽东移、低层切变线东伸的环流背景下,且在700 h Pa存在西南急流和逆温层;850 h Pa温度场上可见明显温度锋区,大气斜压性强;大气可降水量峰值出现在强降雪时段;暴雪过程伴随暖平流增强,暴雪区位于低层冷平流和高层暖平流叠加区域。(2)两次过程的不同点是,"0103"过程先有暖湿气流增强北上,暖湿输送强,存在一定的不稳定层结,动力辐合区深厚,降雪的对流性特征明显,而"0124"过程先有低层冷空气南下形成冷垫,垂直运动发展厚度、暖湿气流强度均不如"0103"过程;强冷空气在华东沿海形成高压,使西风槽东移较慢,造成"0124"过程降雪持续时间长。(3)双偏振雷达整体上正确识别出了两次过程中降水粒子相态,其降水粒子分类产品对预报员开展降雪短临预报具有一定的参考价值。展开更多
文摘利用福建龙岩、漳州、泉州新一代多普勒天气雷达和厦门海沧双偏振雷达探测资料,采用动态地球坐标系下双雷达三维风场反演与拼图技术,基于天气研究和预报模式(Weather Research and Forecasting,WRF)及其资料同化系统,对登陆台风"莫兰蒂"(1614)引起的2016年9月14-15日福建强降水过程进行了双雷达风场反演拼图资料检验及其三维变分同化对强降水精细预报影响的数值试验,结果发现:(1)动态地球坐标系下双雷达反演风场能合理反映实际风场分布状况,其误差相对较小。相较厦门翔安风廓线雷达及厦门探空秒级测风数据,反演风风向(风速)平均绝对误差分别为7.8°(2.6 m/s)及3.4°(1.1 m/s);(2)反演风场水平方向稀疏化对同化及预报结果极为重要,过密的反演风场资料会给同化及预报结果带来负效果。文中采用18、6、2 km 3重嵌套,在3重嵌套区域均进行同化以及仅在2 km区域进行同化两种情况下,均表现为当反演风场资料水平分辨率提高到0.1°时,同化分析及预报的台风环流开始受到负影响;且当反演风场资料水平分辨率越高时,负效果越明显。敏感性试验结果显示,分辨率取0.2°时数值预报效果最好;(3)以美国国家环境预报中心全球预报系统(National Centers for Environmental Prediction/Global Forecast System,NCEP/GFS) 0.5°×0.5°分析场为初值,基于3个不同起报时刻(2016年9月14日14时、20时及15日02时)(北京时,下同)模拟的福建省境内台风内核雨带和螺旋雨带逐时演变、台风路径与强度、逐时降水TS评分和空间相关差异显著,其中14日14时起报试验效果最好;而14日20时起报试验效果最差,这与该试验初始台风大风轴风速明显偏大有关;(4)在上述3个不同起报时刻试验基础上,分别增加双雷达反演风场资料的三维变分同化后,福建境内地面风场和台风内核雨带、螺旋雨带逐时分布、逐时降水TS评分和空间相关�
基金jointly funded by the National Natural Science Foundation of China (Grant Nos. 41675023, 91337103, 91437101 and 41675029)the Scientific Research Projects of CAMS (Grant Nos. 2016Z005 and 2016LASW-B12)the Postgraduate Research & Practice Innovation Program of Jiangsu Province (Grant Nos. KYCX17 0880)
文摘A modified hydrometeor classification algorithm （HCA） is developed in this study for Chinese polarimetric radars. This algorithm is based on the U.S. operational HCA. Meanwhile, the methodology of statistics-based optimization is proposed including calibration checking, datasets selection, membership functions modification, computation thresholds modification, and effect verification. Zhuhai radar, the first operational polarimetric radar in South China, applies these procedures. The systematic bias of calibration is corrected, the reliability of radar measurements deteriorates when the signal-to-noise ratio is low, and correlation coefficient within the melting layer is usually lower than that of the U.S. WSR-88D radar. Through modification based on statistical analysis of polarimetric variables, the localized HCA especially for Zhuhai is obtained, and it performs well over a one-month test through comparison with sounding and surface observations. The algorithm is then utilized for analysis of a squall line process on 11 May 2014 and is found to provide reasonable details with respect to horizontal and vertical structures, and the HCA results---especially in the mixed rain-hail region--can reflect the life cycle of the squall line. In addition, the kinematic and microphysical processes of cloud evolution and the differences between radar- detected hail and surface observations are also analyzed. The results of this study provide evidence for the improvement of this HCA developed specifically for China.
文摘利用常规地面和高空观测资料、地基GPS/MET水汽资料、NCEP再分析资料以及多普勒天气雷达和双偏振雷达资料,对2018年1月3—4日和24—28日先后发生在安徽的两次暴雪过程(以下简称"0103"过程和"0124"过程)的环流背景与动力、热力、水汽输送条件进行对比分析,探讨两次过程降水相态转变过程中大气温度变化的异同。结果表明:(1)两次过程都发生在500 h Pa高空槽东移、低层切变线东伸的环流背景下,且在700 h Pa存在西南急流和逆温层;850 h Pa温度场上可见明显温度锋区,大气斜压性强;大气可降水量峰值出现在强降雪时段;暴雪过程伴随暖平流增强,暴雪区位于低层冷平流和高层暖平流叠加区域。(2)两次过程的不同点是,"0103"过程先有暖湿气流增强北上,暖湿输送强,存在一定的不稳定层结,动力辐合区深厚,降雪的对流性特征明显,而"0124"过程先有低层冷空气南下形成冷垫,垂直运动发展厚度、暖湿气流强度均不如"0103"过程;强冷空气在华东沿海形成高压,使西风槽东移较慢,造成"0124"过程降雪持续时间长。(3)双偏振雷达整体上正确识别出了两次过程中降水粒子相态,其降水粒子分类产品对预报员开展降雪短临预报具有一定的参考价值。
