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引用本文:吴娟,梁萍,林荷娟,吴志勇,钱琦雯.太湖流域梅雨的划分及其典型年异常成因分析.湖泊科学,2021,33(1):255-265. DOI:10.18307/2021.0118
Wu Juan,Liang Ping,Lin Hejuan,Wu Zhiyong,Qian Qiwen.Meiyu determination and causes of typical abnormal Meiyu years in Taihu Basin. J. Lake Sci.2021,33(1):255-265. DOI:10.18307/2021.0118
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太湖流域梅雨的划分及其典型年异常成因分析
吴娟1, 梁萍2, 林荷娟1, 吴志勇3, 钱琦雯4
1.太湖流域管理局水文局(信息中心), 上海 200434;2.上海市气候中心, 中国气象局上海城市气候变化应对重点开放实验室, 上海 200030;3.河海大学水文水资源学院, 南京 210098;4.南京信息工程大学, 南京 210044
摘要:
针对目前尚缺乏客观的流域梅雨划分指标的现状,本文依据最新的梅雨监测国家标准与NCEP/NCAR再分析资料,利用1986—2016年太湖流域水文年鉴逐日雨量整编资料,重新划分了太湖流域入/出梅日期,计算了梅雨特征量,构建了梅雨洪水指数(RFI),并对梅雨期超设计、超警戒洪水年的环流异常成因进行分析.研究表明:(1)新标准下太湖流域多年平均在6月17日入梅,7月11日出梅,梅雨期长度24 d,梅雨量266.8 mm;与历史序列相比,新标准确定的梅雨量一致率较高,其次是入梅时间和出梅时间.(2)雨日数和副高脊线北跳时间是影响入/出梅确定的两个重要因素,新标准将1992、2013年定为空梅,1986、1987、1989、1996、2005年历史入/出梅日期向后调整,1988、2007年出梅日期向前调整,更为合理地反映了梅雨的高温高湿气候特征,客观性较强.(3)梅雨量越大,雨强越大,太湖水位越高,流域越易涝;以梅雨洪水指数作为参考因子,考虑到影响太湖洪水形成的两个关键因子(梅雨期起涨水位、最大7 d降水量占梅雨量的比例),对入梅起涨水位异常偏高、因集中强降雨引起太湖洪水的指示意义较强.(4)高低纬环流配置关系密切,来自西太平洋经南海的偏南气流、印度洋经孟加拉湾的西南暖湿气流汇合后与来自北方的冷空气在太湖流域交汇,太湖流域垂直上升运动异常强烈,触发降雨层结不稳定能量释放,导致暴雨持续形成洪水.
关键词:  太湖流域  梅雨监测指标  降雨强度  梅雨洪水指数
DOI:10.18307/2021.0118
分类号:
基金项目:国家重点研发计划项目(2018YFC0407900,2017YFC1502301)和国家自然科学基金项目(41790471,41775047)联合资助.
Meiyu determination and causes of typical abnormal Meiyu years in Taihu Basin
Wu Juan1, Liang Ping2, Lin Hejuan1, Wu Zhiyong3, Qian Qiwen4
1.Bureau of Hydrology Information Center of Taihu Basin Authority, Shanghai 200434, P. R. China;2.Shanghai Climate Center, Key Laboratory of Cities'Mitigation and Adaptation to Climate Change in Shanghai, CMA, Shanghai 200030, P. R. China;3.College of Hydrology and Water Resources, Hohai University, Nanjing 210098, P. R. China;4.Nanjing University of Information Science and Technology, Nanjing 210044, P. R. China
Abstract:
In order to tackle lacking objective standard problems of Meiyu determination, the Meiyu onset date, ending date, length and rainfall were calculated, based on the latest national standard of Meiyu monitoring indices, NCEP/NCAR reanalysis data, and daily precipitation data from 1986 to 2016. The rainfall-flood index (RFI) was constructed, while the circulation characteristics and causes were analyzed for the designed and alarm flood years. (1) According to the new standard, the multi-year average Meiyu onset date was on June 17th, and the ending date was on July 11st. The multi-year average Meiyu length was 24 days, and the rainfall was 266.8 mm. The results demonstrated that the Meiyu rainfall under the new standard has good relationships with the historical record, which was followed by Meiyu onset date, length and ending date. (2) Both the Meiyu onset and ending date were affected by rain days and the western Pacific subtropical high ridge jumping time. Based on the latest national standard, the Meiyu did not occur in 1992 and 2013, the Meiyu onset and ending dates in 1986, 1987, 1989, 1996, 2005 were suggested to put off, while the ending dates in 1988 and 2007 were suggested to put forward. The high temperature and humidity characteristics of Meiyu for the new standard was more obvious and reasonable. (3) The more intensity index was, the more easily designed and alarm flood occurred. After considering two reference factors: extremely high starting water stage before Meiyu season, as well as proportion between maximum 7 d accumulated precipitation and Meiyu rainfall, the RFI had important indicative significance for flood in Taihu Basin. (4) The warm moisture transport from the west Pacific via South China Sea, and the warm moisture transport from Indian Ocean via the Bay of Bengal, interact with cold air from the north in Taihu Basin. Vertical movement was strong over Taihu Basin. The instability energy releasing was triggered, resulting in continuous rainstorm and flood.
Key words:  Taihu Basin  Meiyu monitoring indices  rainfall intensity  rainstorm-flood index
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