| 下击暴流的雷达预警量化指标研究 |
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| 引用本文： | 罗辉,张杰,朱克云,郑佳锋,范艺,高细桥.下击暴流的雷达预警量化指标研究[J].Acta Meteorologica Sinica,2015,73(5):853-867. |
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| 作者姓名： | 罗辉 张杰 朱克云 郑佳锋 范艺 高细桥 |
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| 作者单位： | 成都信息工程学院大气科学学院, 高原大气与环境四川省重点实验室, 成都, 610225,成都信息工程学院大气科学学院, 高原大气与环境四川省重点实验室, 成都, 610225;成都军区空军气象中心, 成都, 610041,成都信息工程学院大气科学学院, 高原大气与环境四川省重点实验室, 成都, 610225,中国气象科学研究院灾害天气国家重点实验室, 北京, 100081,成都信息工程学院大气科学学院, 高原大气与环境四川省重点实验室, 成都, 610225,成都锦江电子系统工程有限公司, 成都, 610051 |
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| 基金项目： | 国家自然科学基金项目(41275079、91437113)。 |
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| 摘 要： | 下击暴流是一种局地灾害性天气现象,对航空飞行安全有极大危害,也会对地面物体造成严重损害。依据下击暴流发生前母体雷暴(下文简称雷暴)反射率因子核迅速下降的特征,基于雷达体扫数据,定义了判断下击暴流发生、发展的“单位面积等效势能”概念,并结合下击暴流期间雷暴速度场中层辐合的事实,设计得到了下击暴流出流强度公式。结果表明:(1)单位面积等效势能值的变化准确反映了雷暴强中心高度变化。(2)相邻体扫的单位面积等效势能差,反映了雷暴能量的释放量,下击暴流发生前1—2个体扫的单位面积等效势能差达到最大,这反映了下击暴流的爆发;可通过设置单位面积等效势能的释放量为30%,预警下击暴流的发生。(3)单位面积等效势能的释放能够提前6—12 min预警出下击暴流的发生,并通过出流强度公式量化由下击暴流产生的地面大风值。预警风速的误差由雷暴距雷达的距离决定,距离越近风速误差越小,反之亦然。(4)对6次下击暴流预警结果表明,该指标能够准确预警下击暴流的发生,而出流强度受雷暴识别参数的影响较大,远距离误差较大。
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| 关 键 词： | 下击暴流 等效势能 出流强度 中层辐合 |
| 收稿时间： | 2014/12/9 0:00:00 |
| 修稿时间： | 2015/4/21 0:00:00 |
Study of the radar quantitative index of forewarning downburst |
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| LUO Hui,ZHANG Jie,ZHU Keyun,ZHENG Jiafeng,FAN Yi and GAO Xiqiao.Study of the radar quantitative index of forewarning downburst[J].Acta Meteorologica Sinica,2015,73(5):853-867. |
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| Authors: | LUO Hui ZHANG Jie ZHU Keyun ZHENG Jiafeng FAN Yi and GAO Xiqiao |
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| Institution: | Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, Atmosphere Sciences Academy of Chengdu University of Information Technology, Chengdu 610225, China,Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, Atmosphere Sciences Academy of Chengdu University of Information Technology, Chengdu 610225, China;Air Force Meteorological Center of Chengdu Military Region, Chengdu 610041, China,Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, Atmosphere Sciences Academy of Chengdu University of Information Technology, Chengdu 610225, China,State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China,Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, Atmosphere Sciences Academy of Chengdu University of Information Technology, Chengdu 610225, China and Chengdu Jinjiang Electronic System Engineering Co. LTD, Chengdu 610051, China |
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| Abstract: | Downburst is a local severe weather phenomenon. It not only causes great harm to flight safety, but also serious disasters to the ground objects. According to the downburst's characteristic that when downburst happens, it's reflectivity factor core of its matrix drops rapidly. This article is based on the data of the radar scanning, defines the concept of "unit area equivalent potential energy" for judging downburst's occurrence and development and, combining the fact of thunderstorm's velocity field convergence in the mid-level during it's occurrence, then gives the downburst's outflow strength formula. By analyzing the measured data, the calculation results shows: (1) Changes in the unit area equivalent potential value accurately reflect the strong center height variation of thunderstorm. (2) The equivalent potential energy difference of the adjacent volume scan reflects the quantity of thunderstorm's energy released: before the downburst occurs, the potential difference of the 1-2 volumes scan reaches maximum, which reflects outbreak of downburst. By setting the release quantity of the unit area equivalent potential energy to 30% one can early warn the happening of downburst. (3) The release of the unit area equivalent potential energy can early make the warning of downburst occurrence in 6-12 minutes in advance, and through the flow strength formula one can quantify the value of the ground winds generated by the downburst. The error of early warning wind speed is determined by the distance from thunderstorms to radar, the closer it is the smaller the error of wind speed is, and vice versa. And,(4) the six downburst warn results show that the index can accurately warn the occurrence of downburst, while the flow strength is greatly influenced by thunderstorm identification parameters, with the error being larger in the case of the distance farther. |
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| Keywords: | Downburst Equivalent potential energy Outflow strength Middle-levlel convergent |
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