干旱气象 ›› 2019, Vol. 37 ›› Issue (2): 288-300.DOI: 10.11755/j.issn.1006-7639(2019)-02-0288

• 论文 • 上一篇    下一篇

2017年湖南一次特大致洪暴雨过程的水汽特征

蔡荣辉1,2,陈静静1,2,3,文萍4,何炜炜5,陈红专6,李蔚1,2   

  1. 1. 湖南省气象台,湖南 长沙 410118;
    2. 气象防灾减灾湖南省重点实验室,湖南 长沙 410118;
    3. 国防科技大学气象海洋学院,江苏 南京 211101;
    4. 中国气象局预报与网络司,北京 100081;
    5. 湖南省衡阳市气象局,湖南 衡阳 421001;
    6. 湖南省怀化市气象局,湖南 怀化 418000
  • 出版日期:2019-04-30 发布日期:2019-04-30
  • 通讯作者: 陈静静(1983— ),女,河南周口人,高级工程师,博士生,主要从事亚澳季风区大气和水汽输送研究. E-mail:jingjing.chan@qq.com。
  • 作者简介:蔡荣辉(1970— ),男,湖南郴州人,高级工程师,硕士,从事灾害性天气机理研究与预报服务. E-mail:mitas@163.com。
  • 基金资助:
    中国气象局2018年预报员专项(CMAYBY2018-051)、湖南省气象局重点项目(XQKJ16A001、XQKJ17A004)共同资助

Water Vapour Characteristics During a Flood-causing Torrential Rainfall Process in Hunan Province in 2017

CAI Ronghui1,2, CHEN Jingjing1,2,3, WEN Ping4, HE Weiwei5, CHEN Hongzhuan6, LI Wei1,2   

  1. 1. Hunan Provincial Meteorological Observatory, Changsha 410118, China; 
    2. Key Laboratory of Weather Disaster Prevention and Mitigation in Hunan Province, Changsha 410118, China;
    3. College of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China;
    4. Department of Forecasting and Networking, China Meteorological Administration, Beijing 100081, China;
    5. Hengyang Meteorological Bureau of Hunan Province, Hengyang 421001, Hunan, China;
    6. Huaihua Meteorological Bureau of Hunan Province, Huaihua 418000, Hunan, China
  • Online:2019-04-30 Published:2019-04-30

摘要: 利用湖南省区域自动站和常规观测站降水资料、NCEP/NCAR和JRA-55再分析资料及湖南省气象台大气河预报业务产品,分析了2017年6月22日至7月2日湖南一次特大致洪暴雨过程的雨洪和水汽输送异常特征,以及大气河水汽输送对强降雨的影响,在此基础上定量分析了强降雨区各边界的水汽收支状况及各水汽轨迹的贡献。结果表明:此次强降水过程分为三个阶段,第一、第三阶段降雨的范围、强度均明显大于第二阶段。欧亚中高纬稳定的“1槽1脊”环流形势、低纬较稳定的西太副高及其外围强劲的水汽输送是此次暴雨发生的环流背景。水汽通量、水汽通量散度、比湿等物理量的水平及垂直分布对降水的阶段性特征和位置、强度变化有很好的指示作用。三个强降雨时段,来自孟加拉湾、南海和西太副高西南侧的水汽输送表现出不同的强度和位置,造成到达湖南境内的偏南水汽输送空间异常程度不同。大气河的强弱及其水汽输送通道、辐合区位置以及强降雨区各边界水汽净收入对强降水发生、发展起关键作用。水汽后向轨迹分析表明,低层偏南的水汽输送是此次极端强降雨较长时间维持的重要因素,而来自北方的干冷空气侵入利于大气斜压性增强和对流不稳定维持,是第二阶段降水强度弱于第一、第三阶段的另一原因。

关键词: 致洪暴雨, 水汽异常输送, 大气河, 水汽收支, 水汽轨迹

Abstract: Based on the precipitation data at regional automatic stations and conventional weather stations of Hunan Province, NCEP/NCAR reanalysis data, JRA-55 reanalysis data and the forecast products of atmospheric river (AR) from Hunan Provincial Meteorological Observatory, the characteristics of heavy rainfall and abnormal water vapor transport of the flood-causing torrential rainfall in Hunan Province from 22 June to 2 July 2017 and the influence of AR water vapor transport on heavy rainfall were analyzed. And on this basis the water vapor budgets at each boundary over heavy rainfall area and the contributions of water vapor trajectories were analyzed quantitatively. The results show that the torrential rainfall process had three stages, the range and intensity of rainfall at the first and the third stages were significantly greater than those at the second stage. The stable circulation situation with ‘one trough and one ridge’ in middle and high latitudes of Asia and Europe, the relatively stable subtropical high in low latitude and its peripheral strong water vapor transport were weather background of the heavy rainfall. The horizontal and vertical distribution of physical quantities such as water vapor flux, water vapor flux divergence and specific humidity had great indication to the periodic characteristics and the change of location and intensity of rainfall. The intensity and location of water vapor transport from the Bay of Bengal, the South China Sea and the southwest side of the subtropical high were different at three stages of the heavy rainfall process, which caused the spatial difference of southerly abnormal water vapor transport to Hunan. The intensity of AR and its water vapor transport channels, the location of convergence zone and the net water vapor income at each boundary over heavy rainfall zone played a key role in the occurrence and development of the heavy rainfall. The southerly water vapor transport in low level was an important factor of the heavy rainfall lasting for a long time, while the invasion of dry and cold air from the north was beneficial to the enhancement of atmospheric baroclinicity and the maintenance of convection instability, which was another reason why the intensity of rainfall at the second stage was weaker than that at the first and third stages.

Key words: flood-causing torrential rainfall, abnormal transport of water vapor, atmospheric river, water vapor budget, water vapor trajectory

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