王叶红,赵玉春,罗昌荣,韩颂雨. 2019. 双雷达风场反演拼图在登陆台风“莫兰蒂”(1614)强降水精细预报中的同化应用试验[J]. 气象学报, 77(4):617-644, doi:10.11676/qxxb2019.041
双雷达风场反演拼图在登陆台风“莫兰蒂”(1614)强降水精细预报中的同化应用试验
Assimilation experiments for the application of dual-radar retrieval wind mosaics in detailed heavy precipitation forecast produced by landfall typhoon “Meranti” (1614)
投稿时间:2018-04-23  修订日期:2019-01-16
DOI:10.11676/qxxb2019.041
中文关键词:  双雷达  风场反演  同化  台风  强降水
英文关键词:Dual-radar  Wind field retrieval  Assimilation  Typhoon  Heavy precipitation
基金项目:国家自然科学基金(41405106、41675047)、福建省气象局开放式气象科学研究基金(2017K08)、厦门市科技惠民计划项目(3502Z20174052、3502Z20164080)、高原与盆地暴雨旱涝灾害四川省重点实验室开放研究基金项目(SZKT201803)。
作者单位
王叶红 厦门市气象局, 海峡气象开放实验室, 厦门, 361012
高原与盆地暴雨旱涝灾害四川省重点实验室, 成都, 610072 
赵玉春 厦门市气象局, 海峡气象开放实验室, 厦门, 361012 
罗昌荣 厦门市气象局, 海峡气象开放实验室, 厦门, 361012 
韩颂雨 厦门市气象局, 海峡气象开放实验室, 厦门, 361012
浙江省气象信息网络中心, 杭州, 310001 
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中文摘要:
      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、台风环流结构以及U、V风垂直廓线分布均有明显改善,最大正影响时效可达24 h;但仅对1—6 h时效内台风路径有改善。
英文摘要:
      Based on data observed by Doppler weather radars deployed at Longyan, Zhangzhou, Quanzhou and dual polarization Doppler radar deployed at Haicang of Xiamen, the dual-radar three-dimensional wind retrieval and mosaic technique in the dynamic earth coordinate and the WRF (Weather Research and Forecasting) model and its data assimilation system are used to conduct a set of numerical experiments to investigate the impacts of three-dimensional variational assimilation of dual-radar retrieved winds upon the detailed heavy precipitation forecast caused by the landfall typhoon "Meranti" (1614) during the period of 14-15 September 2016 in Fujian Province. The results are as follows:(1) Dual-radar retrieved winds in the dynamic earth coordinate can reasonably describe realistic wind fields, and the errors are relatively small. Comparisons between retrieved winds and wind profiler radar detections during the "Meranti" landfall show that the mean absolute errors of retrieved wind direction and speed are 7.8° and 2.6 m/s, respectively. Comparisons between retrieved winds and Xiamen second radio-soundings show errors of 3.4° and 1.1 m/s, respectively. (2) Horizontal thinning of retrieved winds have obvious impacts upon the assimilation and forecast results. Overly dense retrievals of winds have negative effects on the assimilation and forecast results. A triply nested domain with resolutions of 18, 6, 2 km is used in the present study, and assimilation has been applied to all the domains and only to the innermost domain, respectively. For the above two situations, the typhoon circulation structures from analysis and from forecast both are negatively impacted when the horizontal resolution of retrieved winds reaches 0.1° resolution, and the negative effects are more obvious when the horizontal resolution of the retrieved winds becomes higher. Sensitivity experiment results indicate that numerical forecasts are the best when using 0.2° resolution data. (3) Using NCEP/GFS (National Centers for Environmental Prediction/Global Forecast System) 0.5°×0.5° analysis data as model initial fields, three experiments are carried out at different initialization time, i.e., 14:00, 20:00 BT 14 and 02:00 BT 15 September 2016. It is found that the results with different initialization time are obviously different considering hourly evolution of simulated typhoon inner core and spiral rain band in Fujian Province, typhoon track and intensity, the threat scores and spatial correlation coefficients of hourly precipitation. The simulation initialized at 14:00 BT 14 yields the best result. The simulation initialized at 20:00 BT 14 yields the worst, which is due to the overestimation of initial typhoon maximum wind core. (4) Based on the above three experiments initialized at different time, radar retrieval winds are assimilated by the WRF three-dimensional variational assimilation system. Simulations of hourly surface wind field, typhoon inner core and spiral rain band in Fujian Province, and the threat scores and spatial correlation coefficients of hourly precipitation, as well as typhoon circulation and vertical profiles of zonal and meridional winds all are improved significantly, and the valid time of positive effect is up to 24 h. However, for the simulation of typhoon track, the valid time of positive effect is only six hours.
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