| 广义Ertel-Rossby不变量在北京“7.21”暴雨过程分析中的应用 |
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| 引用本文： | 周玉淑,李娜,孙明生.广义Ertel-Rossby不变量在北京“7.21”暴雨过程分析中的应用[J].气候与环境研究,2014,19(3):303-310. |
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| 作者姓名： | 周玉淑 李娜 孙明生 |
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| 作者单位： | 中国科学院大气物理研究所, 北京100029;中国科学院大气物理研究所, 北京100029;中国科学院大学, 北京100040;北京军区空军气象中心, 北京100061;中国气象科学研究院灾害天气国家重点实验室, 北京100081 |
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| 基金项目： | 国家重点基础研究发展计划项目2014CB441402，国家自然科学基金项目41275065、41075044、41075079，灾害天气国家重点实验室开放课题2012lasw-B07LASW |
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| 摘 要： | 在绝热无摩擦大气中,具有守恒性及可反演性的Ertel位涡(PV)在大尺度天气系统分析中有广泛应用。由于忽略了力管项的作用,PV用于分析中小尺度天气系统演变时受到局限。从广义速度推导得到的广义Ertel-Rossby不变量(GERI)除了包含有PV的守恒性,还包含了螺旋度效应及力管项的作用,对于分析研究快变流型的中小尺度系统演变有一定优势。用GERI分析2012年7月21日北京地区的特大暴雨过程,表明GERI在暴雨区有明显的异常出现,其异常基本与暴雨出现时间同位相,表明GERI的定义涵盖了螺旋度和PV,也包含了暴雨发生时的旋转斜压大气的力管项效应,确实能体现暴雨过程中的流型快变的特点,可以作为独立的变量来分析和揭示造成暴雨的低涡系统的动力结构,为诊断和预报暴雨落区提供新的动力物理量。
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| 关 键 词： | 广义Ertel-Rossby不变量 快变流 暴雨 动力结构 |
| 收稿时间： | 1/4/2013 12:00:00 AM |
| 修稿时间： | 2013/3/13 0:00:00 |
Application of Generalized Ertel-Rossby Invariant to the Heavy Rainfall Case on 21 Jul 2012 in Beijing |
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| ZHOU Yushu,LI Na and SUN Mingsheng.Application of Generalized Ertel-Rossby Invariant to the Heavy Rainfall Case on 21 Jul 2012 in Beijing[J].Climatic and Environmental Research,2014,19(3):303-310. |
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| Authors: | ZHOU Yushu LI Na and SUN Mingsheng |
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| Institution: | Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029
;University of Chinese Academy of Sciences, Beijing 100040;Meteorological Center, Air Force of Beijing Military Region, Beijing 100061
;State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081 |
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| Abstract: | For large-scale weather systems, Ertel potential vorticity (PV) is a very useful quantity because of its properties of material conservation and invertibility for an adiabatic frictionless flow. However, for meso-or small-scale systems, applications of PV are limited because the baroclinic solenoid term, which characterizes baroclinicity of the atmosphere, is removed in PV. An alternative invariant is the generalized Ertel-Rossby invariant (GERI), which is derived from generalized velocity. GERI not only keeps the property of conservation but also includes helicity and the baroclinic solenoidal term, making it more suitable for analyzing evolutions of meso-and small-scale weather systems. In this study, the authors apply GERI to analyze an extreme heavy rainfall case that occurred in Beijing on 21 Jul 2012. It is showed that GERI exhibits large anomalies, having nearly the same phase as the appearance of the heavy precipitation region. It is concluded that GERI makes it possible to characterize fast mode properties during heavy rainfall because of the important physical information it contains, i.e., helicity, PV, and the effect of the solenoidal term. Therefore, GERI can be used to analyze and reveal the dynamical structure of the lower vortex that induces heavy rainfall, and provides a new dynamical quantity for diagnosing and forecasting regions of heavy precipitation. |
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| Keywords: | Generalized Ertel-Rossby invariant Fast-manifold condition Torrential rain Dynamical structure |
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