杨舒楠1, 路屹雄2, 张芳华1, 陶亦为1
Analysis on Causes of Persistent Heavy Rainfall in Tropical Storm Ewiniar
YANG Shunan1, LU Yixiong2, ZHANG Fanghua1, and TAO Yiwei1
(1.National Meteorological Centre;2.National Climate Centre)
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投稿时间:2018-11-19    修订日期:2020-10-29
中文摘要: 本文以热带风暴“艾云尼”(1804)为研究对象,利用常规、非常规观测以及NCEP分析资料等探讨了 “弱”台风的持续性强降水成因。大尺度环流背景导致“艾云尼”引导气流很弱,台风移速缓慢,长时间维持在我国近海。南海季风爆发初期的异常强西南季风和“马力斯”(1805)的偏东急流将水汽、动量持续向台风环流输送。净水汽收支诊断显示,台风影响前期,水汽主要来自南边界;后期,东边界水汽流入增加,维持了台风环流的持续性水汽输入,造成广东沿海水汽通量辐合及高湿、高能环境条件的持续。广东沿海长时间维持较强东南向岸风,在海岸线及沿海地形作用下低层辐合持续,叠加高空辐散,为强降水的持续产生和中尺度对流系统的触发提供了有利动力条件,对流层低层东南风风速增强与降水量陡增吻合较好。台风中尺度对流系统活跃,伴随5个阶段的中尺度对流雨带的发生、发展。沿海地区对流不断新生、中尺度螺旋雨带发展、台风本体降水和外围中尺度对流雨带的叠加以及两条暖湿输送带中海上对流的移入等共同造成广东沿海中尺度对流系统的持续存在和持续性强降水的产生。
Abstract:Ewiniar (1804), a tropical storm with weak TC intensity but strong and long lasting precipitation, was taken as the research object in this study. By using the conventional and unconventional observation, and NCEP analysis date, the causes of persistent heavy precipitation of the "weak" TC were studied. Ewiniar moved very slowly due to the very weak steering flow caused by the large scale circulation background. As a result, its TC circulation maintained for a long time over offshore waters in South China. Water vapor and momentum was transported to the TC circulation continuously by both the abnormal strong southwest jet induced by the onset of the South China monsoon and the easterly jet caused by Maliksi (1805). Diagnosis of net water vapor budget showed that in the early stage, water vapor inflow mainly came from Ewiniar’s southern boundary, and then water inflow in the eastern boundary increased rapidly, which played an important role in maintaining the continuous water input in the whole TC circulation. As a result, the water flux convergence and high humidity and high energy environment along the coastal areas of Guangdong can maintain. Strong southeast onshore wind existed for a long well along the coastal areas of Guangdong. Impacted by the costal line and topography, sustained convergence can be found in lower-level along coastal areas, which can provide favorable dynamic conditions for the continuous generation of heavy rainfall and triggering of mesoscale convective system. And the enhancement of the southeast wind speed in lower troposphere was in good agreement with the sharp increase in precipitation. There were active mesoscale convective systems along the coastal areas, accompanying the occurrence and development of five-stage mesoscale convective rain belts. The continuous generation of new convections in the coastal areas, the development of mesoscale spiral rain band, the superposition of TC inner core precipitation and convections in the outer rain belt, and the migration of convection over sea from the two warm wet conveyor belts all contributed to the persistence of the mesoscale convective system in the coastal area of Guangdong Province, resulting in the generation of persistent heavy rainfall there.
文章编号:201811190506     中图分类号:    文献标志码:
杨舒楠,路屹雄,张芳华,陶亦为,0.[en_title][J].Meteor Mon,():-.
YANG Shunan,LU Yixiong,ZHANG Fanghua,and TAO Yiwei,0.Analysis on Causes of Persistent Heavy Rainfall in Tropical Storm Ewiniar[J].Meteor Mon,():-.