doi:  10.3878/j.issn.1006-9895.1901.18239
两个相似路径台风残余造成局地特大暴雨的成因机制和能量收支对比分析

Comparative analyses on mechanism and energy budget of local extreme rainfall events caused by remnant clouds of two typhoons with similar tracks
摘要点击 74  全文点击 23  投稿时间:2018-10-17  修订日期:2019-01-28
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基金:  国家自然科学基金,中国气象局关键技术发展专项,浙江省科技重大项目
中文关键词:  台风 局地特大暴雨 辐散动能 旋转动能
英文关键词:  Typhoon, Local extreme rain, Divergent kinetic energy, Rotational kinetic energy
              
作者中文名作者英文名单位
潘劲松Pan Jinsong浙江省气象台
周玲丽Zhou Lingli浙江省气象台
陆玮Lu Wei
罗玲Luo Ling浙江省气象台
翟国庆Zhai Guoqing浙江大学地球科学系
引用:潘劲松,周玲丽,陆玮,罗玲,翟国庆.2019.两个相似路径台风残余造成局地特大暴雨的成因机制和能量收支对比分析[J].大气科学
Citation:Pan Jinsong,Zhou Lingli,Lu Wei,Luo Ling,Zhai Guoqing.2019.Comparative analyses on mechanism and energy budget of local extreme rainfall events caused by remnant clouds of two typhoons with similar tracks[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      本文利用EC-Interim 0.5°×0.5°再分析资料、自动站小时和分钟加密资料、风云2G(FY2G)卫星红外云图及多普勒雷达和风廓线雷达资料对2015年路径高度相似的“苏迪罗”和“杜鹃”台风在浙江沿海引发的局地特大暴雨进行对比分析。这两次降水过程都是在台风减弱为热带低压甚至残压并深入内陆远离浙江沿海后发生的。结果表明,“苏迪罗”降水过程是由低层强东南和偏南急流长时间辐合加上有利地形共同作用导致的;经向环流背景下来自季风持续的水汽输送有利于“苏迪罗”维持较长的生命史和稳定的降水。“杜鹃”残压特大暴雨的触发系统则是高纬地面冷高压底部的东东北出流南下与“杜鹃”北象限的东东南风交汇形成的中尺度倒槽;纬向环流和强盛副高造成的弱引导气流及夏季风南撤和低涡卷挟造成的水汽通道断裂是“杜鹃”登陆后快速减弱为残压和降水维持时间较短的原因。两次台风降水过程中均无外部动能输送和来自有效位能的动能转换。动能收支的主要影响因子为中低层局地次网格运动间的能量转换、旋转风和散度风效应及下垫面的摩擦耗散。所以,虽然“杜鹃”的对流有效位能很小,但仍可造成强对流和特大暴雨。此外,降水过程中释放的凝结潜热造成的局地非绝热加热使气柱中显热能大量累积,促使地面中小尺度涡旋和倒槽不断加深,造成降水的增幅。
Abstract:
      Using 0.5°×0.5° EC-Interim analysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF), hourly and minutely observational data from Automatic Weather Station (AWS), Doppler radar and wind profile radar, as well as infrared cloud image from Fengyun 2G Satellite (FY2G), we investigate two local torrential rain events in coastal Zhejiang Province caused by typhoon Soudelor and Dujuan with similar tracks in 2015. Both of the rains were generated after the typhoons had got weakened to tropical depression (TD) or remnants and travelled far away from Zhejiang. It is found that the rain event associated with Soudelor is triggered by long-time convergence of strong low-level southeast jet and south jet as well as inducible topography. Meridional circulation with persistent water vapor transfer by summer monsoon provides favorable background for the long-lasting life cycle of Soudelor and precipitation. Differently, the rain brought about by remnants of Dujuan is produced by a mesoscale inverted trough comprised of the east-northeast flowing out of the ground cold high in high latitudes and the east-southeast wind in north quadrant of Dujuan. Zonal circulation, weak steering current under powerful western pacific subtropical high, water vapor transportation cut off by monsoon retreat and vortex entrainment are reasons for rapid decay of Dujuan and less lasting time of rain than that of Soudelor. There is no external transfer or Convective Available Potential Energy (CAPE) conversion of kinetic energy for both rain events. Rotational divergent wind effects and the energy transfer between resolvable and unresolvable scale motions as well as frictional processes in lower and middle levels are main-impact factors to kinetic energy budgets during these two rain events. As a result, forceful convection and heavy rain occur despite of small CAPE of Dujuan. The diabatic heating associated with condensation latent heat released by local precipitation massively increases the sensible heat energy in air column and consequently potentially promotes the meso- and micro-scale vortex and inverted trough. As a result, the rain events are intensified and sustained.
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