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首页|期刊导航|南京大学学报(自然科学版)|河南"21.7"特大暴雨的区域集合预报检验和预报偏差分析

河南"21.7"特大暴雨的区域集合预报检验和预报偏差分析OA北大核心CSTPCD

Verification and error analysis of regional ensemble forecasts for the torrential rain on 20 July 2021 in Henan province

中文摘要英文摘要

河南"21.7"特大暴雨覆盖范围广、强度大、降水时间段集中,造成了严重损失.利用中国气象局(China Meteorological Administration,CMA)多源融合降水分析产品(CMA Multisource Precipitation Analysis System,CMPAS-V2.1)和欧洲中期天气预报中心ERA5再分析数据,对CMA区域集合预报系统(Regional Ensemble Prediction System,CMA-REPS)在此次暴雨事件中降水最强时间段(2021年7月20日14-20时,北京时)的预报结果进行了评估与分析.研究结果显示,预报时效越短,集合平均和概率预报的降水效果越好,但降水强度与大值落区依然存在较大的预报偏差.结合多种降水预报评分筛选出最好和最坏的集合成员,并通过对比环流形势、水汽条件等因素,探讨了降水预报偏差的成因.好成员在郑州地区预测了占总降水30%的对流性降水,而坏成员则未能预报出对流性降水,两者总降水的偏移与非对流性降水的表现一致.好成员预测的降水区域偏向东北,与预报的副高位置偏东、台风"查帕卡"路径偏北以及南风偏强有关;坏成员预测的降水区域偏西,与相对湿度的大值区偏移一致,可能是因为预报的台风"烟花"引导的低层东风更强.在925 hPa上,好成员成功预测出郑州西部山脉迎风侧的强辐合区,导致超过25 mm·(6h)-1的强降水从山前延伸至地形高度800 m以上的迎风坡.相比之下,由于预报的辐合区域小、强度弱,坏成员的强降水仅分布在600 m以下的山前区域.总体而言,CMA-REPS对此次强降水过程的预报偏差主要源自大气环流的模拟偏差以及复杂地形作用.

In July 2021,Henan province experienced widespread,intense,and concentrated extremely heavy rainfall,resulting in significant damage.This paper evaluates the forecast performance of the China Meteorological Administration(CMA)Regional Ensemble Forecast System(CMA-REPS)during the heaviest precipitation period from 1400 to 2000 China Standard Time on 20 July 2021,using the CMA Multisource Precipitation Analysis System(CMPAS)-V2.1 product and the fifth generation European Centre for Medium-Range Weather Forecasts(ECMWF)reanalysis(ERA5).The study findings reveal that shorter lead times yield improved precipitation forecasts in terms of ensemble mean and probabilistic forecasts.However,notable forecast biases persist in precipitation intensity and spatial coverage of heavy rainfall.The best and worst ensemble members were identified by combining several precipitation verification scores.An analysis of atmospheric circulation and water vapor conditions was conducted to explore potential causes of precipitation forecast errors.The study identified that a good ensemble member successfully predicted convective precipitation,accounting for 30%of total precipitation in the Zhengzhou area,whereas a bad member failed to forecast convective precipitation.The overall precipitation distribution in both members aligned with the performance of non-convective precipitation.The precipitation area of the good member shifted northeastward,which is associated with the eastward deviation of the forecasted subtropical high position,the northward track deviation of typhoon"Cempaka",and the stronger south wind.In contrast,the precipitation area of the bad member shifted westward,consistent with the deviation of the maximum relative humidity area,possibly due to a stronger low-level east wind transported by the forecasted typhoon"Infa".At the 925 hPa level,the good member accurately predicted a strong convergence zone on the windward slope of the western mountains near Zhengzhou,causing intense rainfall exceeding 25 mm·(6 h)-1,extending from the foothills to elevations above 800 m.Conversely,the bad member predicted a small and weak convergence zone,leading to heavy rainfall confined to the foothill areas below 600 m.Overall,the forecast errors of CMA-REPS for this heavy rain event are primarily attributed to the simulated deviation of atmospheric circulation and the complex orographic effect.

廉丹华;袁慧玲;王婧羽;陈法敬

中尺度灾害性天气教育部重点实验室,南京大学大气科学学院,南京,210023中尺度灾害性天气教育部重点实验室,南京大学大气科学学院,南京,210023||南京大学关键地球物质循环前沿科学中心,南京,210023中尺度灾害性天气教育部重点实验室,南京大学大气科学学院,南京,210023||中国气象局武汉暴雨研究所暴雨监测预警湖北省重点实验室,武汉,430205中国气象局地球系统数值预报中心,北京,100081

大气科学

集合预报"21.7"河南暴雨概率预报预报检验

ensemble forecastthe torrential rain in July 2021 in Henan provinceprobabilistic forecastforecast verification

《南京大学学报(自然科学版)》 2024 (002)

287-300 / 14

国家自然科学基金(U2342218)

10.13232/j.cnki.jnju.2024.02.010

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