| 灾害性大风发生机理与飑线结构特征的个例分析模拟研究 |
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| 引用本文： | 刘香娥,郭学良.灾害性大风发生机理与飑线结构特征的个例分析模拟研究[J].大气科学,2012,36(6):1150-1164. |
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| 作者姓名： | 刘香娥 郭学良 |
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| 作者单位： | 1.中国科学院大气物理研究所, 北京 100029;中国科学院研究生院, 北京 100049 |
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| 基金项目： | 公益性行业(气象)科研专项GYHY200806001;国家科技支撑计划资助项目2006BAC12B03 |
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| 摘 要： | 2009年6月3日在我国河南发生了历史罕见的强飑线天气过程, 造成了严重的人员伤亡和灾害。为了解此次飑线天气的特征和产生的机理, 本文采用卫星、雷达及地面加密观测资料, 结合中尺度WRF(Weather Research and Forecasting)数值模式, 研究了此次飑线产生的天气背景、宏微观结构特征及造成灾害性大风的机理。结果表明, 此次飑线过程的主要影响系统是东北冷涡, 其后部横槽引导的南下冷空气与西南暖湿气流在河南新乡南部一带交汇促发强对流过程, 最后演变为飑线。但由于低层西南风偏弱, 水汽条件不足, 飑线发生的环境较为干冷。飑线产生区大气处于条件性不稳定状态, 对流有效位能(CAPE, Convective Available Potential Energy)在1300 J/kg左右, 并具有适平的垂直风切变。地面气象场显示飑线具有相对冷湿的雷暴高压和强冷池, 飑线过程产生的灾害性天气以大风而非强降水为主。数值模式结果显示飑线下沉气流的最大值仅为-13 m/s, 而地面风速最大值达到35 m/s, 是最大下沉气流的2.7倍。进一步的数值敏感试验表明, 降水粒子的蒸发和融化冷却过程对降低地面温度和产生地面强风速具有重要影响, 其中雨水蒸发过程产生的最大等效冷却率为-3 K/min, 远大于霰融化冷却率-0.7 K/min, 因此雨水蒸发过程是影响冷池强度的关键因素, 而地面强冷池在此次飑线灾害性大风的产生中具有重要作用。
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| 关 键 词： | 飑线 灾害性大风 冷池 观测与数值模拟 |
| 收稿时间： | 2011/11/4 0:00:00 |
| 修稿时间： | 2012/6/21 0:00:00 |
Analysis and Numerical Simulation Research on Severe Surface
Wind Formation Mechanism and Structural Characteristics
of a Squall Line Case |
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| LIU Xiang'e
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GUO Xueliang.Analysis and Numerical Simulation Research on Severe Surface
Wind Formation Mechanism and Structural Characteristics
of a Squall Line Case[J].Chinese Journal of Atmospheric Sciences,2012,36(6):1150-1164. |
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| Authors: | LIU Xiang'e GUO Xueliang |
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| Institution: | 1.Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;Graduate University of Chinese Academy of Sciences, Beijing 1000492.Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;Chinese Academy of Meteorological Sciences, Beijing 100081; |
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| Abstract: | An unusually severe squall line resulted in significant losses of lives and property on June 3, 2009, in Henan, China. To better understand the characteristics and production mechanism of the squall line, the data of satellite, radar, intensive surface observation, and the mesoscale Weather Research and Forecasting (WRF) model were used to investigate the atmospheric background, macrostructure, and microstructure of the squall line and the formation mechanism of the damaging surface wind. The results show that a northeast cold vortex was the main influencing system of the squall line. The transversal trough located at the back of the northeast cold vortex induced a strong cold airflow, which met with a relatively weak southwesterly warm and moist airflow to produce convection. The system further developed in the study region as a severe squall line. The atmosphere contained weak southwesterly winds and water vapor at low layers; thus, the atmospheric environment of the squall line formation was dryer. The atmosphere was conditionally unstable with a convective available potential energy (CAPE) index of approximately 1300 J/kg and adequate wind shear. A relatively cold and moist high with thunderstorms and a strong cold pool on the surface field occurred concurrently with the squall line to produce severe surface wind rather than heavy rain. The results of the WRF model showed that although the maximum downdraft of the squall line was only -13 m/s, the surface outflow wind speed was 35 m/s, which exceeds the maximum downdraft by a factor of 2.7. Further investigation revealed that the cooling processes of rain evaporation and graupel melting are the major contributors to the decrease in surface temperature and strong wind production. Among them, the cooling rate due to rain evaporation was approximately -3 K/min while that due to graupel melting was approximately -0.7 K/min. Therefore, the key factor to influence the cold pool intensity was rain evaporation; this cold pool played a critical role in the formation of the severe surface winds during the squall line event. |
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| Keywords: | squall line severe surface winds cold pool observation and numerical simulation |
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