• CN 62-1175/P
• ISSN 1006-7639

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

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

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.

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