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地形对山西垣曲“0729”特大暴雨影响的数值模拟分析

董春卿1苗爱梅1郭媛媛1张磊2   

  1. 1.山西省气象台,山西 太原 030006;2.安徽省池州市气象局,安徽 池州 247000
  • 出版日期:2015-06-30 发布日期:2015-06-30
  • 作者简介:董春卿(1984-),男,工程师,主要从事区域精细化数值天气预报研究.E-mail:dongchq@gmail.com
  • 基金资助:

    中国气象局2014年气象关键技术集成与应用(面上)项目“精细化空气质量预报技术应用”(CMAGJ2014M09)、山西省气象局重点科研项目“基于中尺度模式的山洪地质灾害精细化气象预报系统”(SXKZDTQ20138701)及“山西省环境空气质量预报数值模式研究”(SXKZDTQ20140601)共同资助

Numerical Simulation of Effects of Terrain on Yuanqu “0729” Severe Torrential Rain Event

DONG Chunqing 1, MIAO Aimei1, GUO Yuanyuan1, ZHANG Lei2   

  1. 1.Shanxi Meteorological Observatory, Taiyuan 030006, China;2.Chizhou Meteorological Bureau of Anhui Province, Chizhou 247000, China
  • Online:2015-06-30 Published:2015-06-30

摘要:

利用WRF-ARW中尺度数值模式,对山西南部垣曲县喇叭口地形造成的“0729”特大暴雨过程进行了数值模拟和地形敏感性试验,通过分析暴雨云团的动力和微物理结构,探讨地形激发积层混合云系的结构特征及地形对暴雨云系的影响。结果表明:西风带系统与副热带系统相向而行是此次暴雨发生的环流背景特征,当中低空受偏南风急流影响时,垣曲县向南开放的喇叭口地形可使低层的辐合上升显著增强。特殊地形所激发的meso-β积层混合云团是造成此次特大暴雨的直接系统。地形敏感性试验结果表明:地形的变化对积层混合云系的动力结构、微物理特征等有显著影响。地形降低后,喇叭口效应形成的低层强辐合结构与强上升气流消失;下风方向低层辐合、中高层辐散配合强烈的上升运动,对流发展趋于旺盛,暴雨中心向地形下游移动。地形的变化对水相物质的微物理结构也有显著的影响。地形降低后,迎风坡上空上升运动减弱,进入到中间层上层的云水粒子减少,凝华生成的冰晶粒子减少,“播撒—供给”机制减弱,迎风坡降水强度明显减弱;下风方向对流加强,更多的云水粒子进入到中间层上层,降水强度加强。喇叭口地形的存在更有利于上游强对流发展并形成层积混合云系,对下游对流起抑制作用。

关键词: 特大暴雨, 地形敏感性试验, 积层混合云系, 微物理结构

Abstract:

On July 29, 2007, a torrential rain event occurred in Yuanqu in the south of Shanxi Province, which was regarded as a typical trumpet-shaped orographic torrential rain event. In order to study the orographic effect in the event, numerical simulation was conducted with the Weather Research and Forecasting Model (WRF). The results show that the meeting of westerly zone system and subtropical high pressure on each halfway was the circulation background characteristics, and the meso-β stratiform clouds with convective clouds excited by special terrain were the direct system of the rain storm. The terrain sensitivity test indicated that the change of terrain had a significant impact on the dynamic structure and the micro-physical characteristics of stratiform clouds with convective clouds. When removed the trumpet-shaped terrain around Yuanqu, the strong convergence on low layer and strong upward motion would disappear, while a convergence would occur on the low layer and a divergence would be found on the middle and top layers in downstream, and the development of convective clouds would be more active in downstream, therefore, the storm center would be shifted downstream. The number of cloud water into the upper middle layer would be reduced, and the seeds of Seeder-feeder mechanism would be decreased because of weaker upward motion over storm area, which finally resulted significantly weakened rainfall intensity in upstream. The development of convective clouds would be more active in downstream, and more cloud water would be lifted into the upper middle layer, which finally resulted significantly enhanced rainfall intensity in downstream. The trumpet-shaped terrain was more beneficial to the development of upstream strong convection, and the formation of stratiform clouds with convective clouds, and unfavorable to the development of downstream convection.

Key words: torrential rain, terrain sensitivity test, stratiform clouds with convective clouds, micro-physical characteristics

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