浙江省梅雨期降水日变化及ECMWF预报能力评估  

Diurnal change of rainfall during plum rainy season Meiyu period in Zhejiang Province and assessment on prediction capacity of ECMWF

作　　者：汪冬冬 方艳莹 申华羽 涂小萍 吕劲文 钱峥 WANG Dongdong;FANG Yanying;SHEN Huayu;TU Xiaoping;LYU Jingwen;QIAN Zheng(Ningbo Meteorological Service Center,Ningbo 315000,Zhejiang,China;Ningbo Meteorological Disaster Emergency Warning Center,Ningbo 315000,Zhejiang,China;Ningbo Meteorological Observatory,Ningbo 315000,Zhejiang,China)

机构地区：[1]宁波市气象服务中心,浙江宁波315000 [2]宁波市气象灾害预警中心,浙江宁波315000 [3]宁波市气象台,浙江宁波315000

出　　处：《水利水电技术（中英文）》2023年第7期36-49,共14页Water Resources and Hydropower Engineering

基　　金：宁波市公益性计划重点项目(2022S181);宁波市自然科学基金项目(202003N4192,202003N4193);浙江省气象局预报员专项项目(2021YBY05);浙江省“海洋与港航气象”创新团队资助。

摘　　要：【目的】为了解浙江省梅雨期的降水日变化特征以及气象业务模式对降水的预报能力。【方法】利用2008—2019年期间浙江地面雨量站小时数据和ERA-Interim再分析资料进行分析,同时评估ECMWF在浙江地区梅雨期的预报水平。【结果】结果表明:(1)梅雨期间浙江平均日降水量自西向东递减,浙西地区从05:00—18:00一直维持强降水的特征,平均最大日降水量超过20 mm。(2)浙中、浙北、浙东降水呈双峰型特征,主要降水时段在03:00—11:00和13:00—20:00。浙东北和浙南降水呈单峰型特征,浙东北降水峰值主要在03:00—10:00,但浙南降水峰值主要在14:00—21:00。除浙南外,梅雨期间浙江大部地区夜间至早晨强降水持续时间比午后至傍晚更长。(3)夜间至早晨强降水与低空急流(LLJ)在夜间逐渐加强密切相关。因为夜间至早晨期间,非地转风逐渐加强,使得LLJ增强,而增强的LLJ为浙江地区带来大量暖湿气流,提供不稳定能量,增强辐合上升运动,进而造成早晨降水峰值。午后热力条件可能是午后至傍晚强降水的主要原因。(4)ECMWF基本可以预报出浙江梅雨期间的降水趋势,但夜间至早晨(02:00—11:00)的降水趋势预报优于午后至傍晚(14:00—20:00)。【结论】总体上,ECMWF在夜间至早晨期间更倾向低估强降水,高估弱降水。模式对夜间至早晨的降水预报相对不够稳定,均方根误差大于午后至傍晚。随着预报时间的延长,模式预报能力降低。[Objective]In order to understand both the diurnal changing characteristics of rainfall and the prediction capacity of meteorological operational mode during the plum rainy season Meiyu period in Zhejiang Province,[Methods]the hourly data of ground rainfall stations and the ERA-Interim data during the period from 2008 to 2019 in Zhejiang Province are analyzed herein,while the prediction level of ECMWF during plum rainy season Meiyu period in the province is assessed as well.[Results]The result show that(1)the mean daily precipitation during the plum rainy season Meiyu period in Zhejiang Province progressively decreases from west to east,while the characteristics of strong precipitation maintains from 05:00 to 18:00 all along within the western region of Zhejiang Province with the maximum daily precipitation over 20 mm;(2)the rainfall in the regions of the Central,Northern and Eastern Zhejiang exhibit bimodal characteristics with the main precipitation periods of 03:00—11:00 and 13:00—20:00,while the precipitations in the northeastern and southern Zhejiang mainly exhibit unimodal characteristics,but the precipitation peak of the southern Zhejiang mainly concentrates in the period of 14:00—21:00.Besides the southern Zhejiang,the heavy precipitation durations from night to morning within most of the regions in Zhejiang Province are more longer than those from afternoon to evening;(3)the heavy precipitation from night to morning is closely related to the gradual strengthening of the low-level jet(LLJ)at night.Due to the gradual strengthening of ageostrophic wind from night to morning,the low-level jet(LLJ)is enhanced,however,the enhanced low-level jet(LLJ)brings a large amount of warm and humid air,provides unstable energy,and enhances convergence ascending movement,and then causes morning precipitation peak,while the thermal conditions in the afternoon is possible to be the main causation for the heavy precipitation from afternoon to evening;(4)the precipitation trend during plum rainy season Meiyu period of Z

关 键 词：梅雨 降水日变化 浙江 低空急流 ECMWF 评估 降雨 气候变化 

分 类 号：TV213.4[水利工程—水文学及水资源]