Journal of Arid Meteorology

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Analysis on the Reasons for the Heavy Rainfall Associated with the Reinforcing Outer Spiral Rainband in Zhejiang Caused by Typhoon Meranti

DUAN Jingjing 1,2, QIAN Yanzhen1, GUO Jianming1   

  1. 1. Ningbo Meteorological Observatory of Zhejiang Province, Ningbo 315012, Zhejiang, China)
    (2. Shanghai Typhoon Institute, China Meteorological Administration, Shanghai 200030, China
  • Online:2019-02-28 Published:2019-02-28

“莫兰蒂”外螺旋雨带在浙江局地发展引发大暴雨成因分析

段晶晶1,2钱燕珍1郭建民1   

  1. 1.浙江省宁波市气象台,浙江宁波315012;2.上海台风研究所,上海200030
  • 作者简介:段晶晶(1983— ),女,博士,主要研究方向为台风动力学及数值模拟. E-mail: duanduan1110@163.com。
  • 基金资助:

    宁波市自然科学基金项目(2018A610210)、上海市气象局台风科技创新团队项目和浙江省气象局预报员专项项目(2017YBY03)共同资助

Abstract:

The possible reasons for heavy rainfall during 13-16 September, 2016 caused by typhoon Meranti in Zhejiang Province were  investigated by using numerical simulation output, NCEP reanalysis data, observed precipitation data from automatic stations and the Black Body Temperature data from infrared satellite observation. It was found that the heavy rain occurred on the right flank of the typhoon. The low-layer troposphere southeasterly flow promoted the reinforcing of the outer spiral rainbands in the northeastern quadrant of the typhoon after making landfall in Fujian, leading to an enhanced precipitation in Zhejiang. The control simulation indicated that the significant southeasterly to the southerly winds in the east of the typhoon led to the development of small-scale convective system in the outer spiral rainbands. These small-scale convective coupling systems were characterized by alternative positive and negative vorticity centers, corresponding with updrafts and downdrafts in the northeast of Meranti. The heavy precipitation region was accompanied with obvious wavelike structure. Diagnostic analysis also showed that the significant southeasterly to the southerly winds in the east of the Meranti were closely related to the typhoon Malakas and a large cyclonic gyre over the island of Taiwan on a quasi-biweekly oscillation time scale. The sensitivity experiments showed that typhoon Malakas and the quasi-biweekly oscillation played an important role in the northwestward-moving track, and water vapor transport and precipitation distribution.

Key words: Key words: typhoon, heavy rainfall, quasi-biweekly oscillation, outer spiral rainband, small-scale conv

摘要:

利用诊断和数值模拟相结合的方法,分析了2016年9月13—16日“莫兰蒂”台风在登陆福建南部北上后给浙江沿海地区带来的局地大暴雨天气,发现这次局地大暴雨发生在台风移动路径右侧,对流层低层强盛的东南气流促进了台风登陆减弱后其东北侧外螺旋雨带局地发展,导致这一区域对流发展旺盛,在浙江引发大暴雨天气。控制试验表明“莫兰蒂”东侧显著的东南到偏南气流导致外螺旋雨带中小尺度对流系统的发生发展,在“莫兰蒂”东北侧存在小尺度的对流耦合系统,小尺度雨带在涡度场和垂直运动场上正、负涡度中心和上升、下降运动交替分布的中小尺度波列结构明显,强降水就发生在此处。台风东侧显著的东南到偏南气流与“莫兰蒂”东南侧的“马勒卡”台风以及10~20 d的带通滤波场上台湾岛附近的气旋性涡旋密切相关。敏感性试验表明“马勒卡”台风和准双周振荡都对“莫兰蒂”路径有很重要的西北行引导作用,进而影响东南气流水汽输送和降水分布。

关键词: 台风, 暴雨, 准双周振荡, 外螺旋雨带, 小尺度对流系统

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