Journal of Arid Meteorology

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Cause Analysis on a Heavy Rainfall over the Yangtze-Huaihe Area in July 2013

YANG Xiumei, MA Minjin, ZHU Anbao   

  1. College of Atmospheric Sciences, Lanzhou University, Key Laboratory of Arid Climate
     Change and Reducing Disaster of Gansu Province, Lanzhou 730000, China
  • Online:2016-08-31 Published:2016-08-31

2013年7月一次江淮暴雨成因分析

杨秀梅马敏劲朱安豹   

  1. 兰州大学大气科学学院,甘肃省干旱气候变化与减灾重点实验室,甘肃兰州730000
  • 通讯作者: 马敏劲(1983- ),男,博士,云南昭通人,副教授,主要研究方向为大气边界层、空气污染和数值模拟. E-mail:minjinma@lzu.edu.cn
  • 作者简介:杨秀梅(1990- ),女,甘肃会宁人,硕士研究生,主要从事空气污染方面的研究. E-mail:18751977375@163.com
  • 基金资助:

    国家自然科学青年基金“兰州日间稳定边界层生消机制及其环境效应的数值模拟研究”(41205008)、中国气象局兰州干旱气象研究所干旱气象科学研究基金(IAM201209)和中央高校小额探索项目“西北地区复杂下垫面大气边界层高度数值模拟研究”(2022014zr0120)共同资助

Abstract:

A continuous heavy rainfall occurred in the Yangtze-Huaihe area from 5 to 7 July 2013. It was the first continuous rainstorm since the plum rain began, which caused flood disasters in the Yangtze-Huaihe area. Based on the ECMWF reanalysis data with 1°×1°spatial resolution, cloud cover data of FY-2F satellite and daily precipitation from 72 weather stations in the Yangtze-Huaihe area from 5 to 7 July 2013, the circulation characteristics and cause of the heavy rainfall were analyzed. The results showed that the slow-moving southwest vortex over the Yangtze-Huaihe region was critical to the persistent heavy rainfall under the background of the radial circulation on 500 hPa. When the southwest vortex moved close to the Meiyu front, the southwest vortex developed strongly and moved slowly. The high-level jet, upper-level trough on 500 hPa, low-level southwesterly jet, southwest vortex, boundary-layer jet and Meiyu front acted together to form deep convergence layer. The atmospheric vertical structure of the high-level divergence and low-level convergence strengthened the pumping action, and furtherly promoted the development of vertical movement. The strong vertical wind shear over the boundary layer triggered the convective instability release. The southwesterly jet in the boundary layer transported water vapor from the Bengal and South China Sea to the Yangtze-Huaihe region, which brought better vapor and thermal condition for the storm district. The intersection of warm air from the south and cold air from the north of China over the Yangtze-Huaihe area formed a dense zone of pseudo equivalent potential temperature, which resulted in the ascending motion with synoptic scale, and the rain belt mainly located in the south side of the dense zone of pseudo equivalent potential temperature, which could be a reference to the rain area forecast.

Key words: upper-level trough, continuous rainstorm, southwest vortex, pseudo equivalent potential temperature

摘要:

013年7月4—7日江淮地区出现了入梅以来的第一次持续性暴雨,造成江淮地区严重的洪涝灾害。利用欧洲中期天气预报中心(ECMWF)逐6 h的1°×1°再分析资料、FY-2F卫星云量资料和江淮地区72个气象站逐日降水资料,对此次暴雨过程的成因进行分析。结果表明:在500 hPa以径向环流为主的背景形势下,江淮地区上空缓慢移近梅雨锋的西南涡是此次降水过程的关键系统。高空急流、500 hPa高空槽、西南低空急流、西南涡、边界层急流和梅雨锋共同作用形成深厚的辐合层,低层辐合、高层辐散的垂直结构增强了大气的抽吸作用,造成强烈的垂直运动。边界层强的垂直风切变触发了对流不稳定能量的释放。来自孟加拉湾和南海的水汽通过西南超低空急流向江淮地区输送,为江淮地区带来水汽和热力条件。南方暖空气和北方冷空气交汇于江淮地区,形成假相当位温密集带,产生天气尺度的上升运动,雨带主要位于密集带的南侧,可作为雨区预报的参考。

关键词: 高空槽, 持续性暴雨, 西南涡, 假相当位温

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