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! f8 y* ` m. g3 i/ P& }# C: M渤海湾阵风锋垂直结构特征及维持机制分析
& G- n0 c0 v9 _作者：许长义1 王彦2 单位：1. 天津市滨海新区气象局, 天津 300457;& d f' C7 J+ e! X3 C g! ~
2. 天津市人工影响天气办公室, 天津 300074 分类号：P732.1: K& J* L5 ~. \" a$ H: c
出版年·卷·期（页码）：2021·38·第六期（21-32） 摘要：利用多普勒天气雷达、风廓线雷达、VDRAS反演资料和地面加密自动站等资料，分析了从渤海湾西岸和南岸移入的两条阵风锋发展演变过程及其维持机制。结果表明：西岸阵风锋处于“亚最优切变态”，垂直伸展厚度为1.8 km，对流层低层强盛的西南暖湿气流沿阵风锋输送到雷暴中，强冷空气堆下沉与近地层暖湿空气形成的气压和温度梯度密集区造成8级雷暴大风。区别于经典阵风锋，南岸阵风锋处于“最优切变态”，冷池传播速度与低层垂直切变基本持平，边界层呈现强东北气流入流（150～750 m），垂直伸展更为深厚（2.6 km），地面冷池与低层垂直风切变对其发展维持起到重要作用。雷暴母体伴有后侧入流急流（RIJ）侵入到达阵风锋处，RIJ下沉过程中将干冷空气夹卷进入下沉气流，通过蒸发作用产生负浮力使冷空气加速下沉，加之降水粒子的拖曳作用，加强了下沉气流强度，最终造成10级以上灾害性大风。计算表明南岸阵风锋冷池传播速度与低层垂直风切变相平衡，较地面大风强1个量级。 关键词：阵风锋 垂直结构 冷池 垂直切变 维持机制 Abstract：Using Doppler radar, wind profile radar, VDRAS and automatic weather station data, we analyze the evolution process and maintenance mechanism of two gust fronts that move into the Bohai Bay from the west and south coast on 10 June 2016, which is helpful to further understand the development and maintenance mechanism of thunderstorm gust front in the coastal sea areas. The results show that the strong dry layer in the middle layer and vertical wind shear are the key mesoscale environmental factors that causes the generation of thunderstorm and hazardous wind. The gust front from west shore is in a"suboptimal shear state"with a vertical extension thickness of 1.8 km, and the state continues when the gust front moves into the Bohai Bay. The southwest warm and humid inflow in lower layer is transported to thunderstorm along with gust front. The pressure and temperature gradient is generated by the sinking of strong cold air and the near-surface warm and humid air, which causes hazardous wind. The gust front from south shore is in an"optimal shear state"and is strengthened after moving into the Bohai Bay with a vertical extension thickness of 2.6 km. The gale intensity is closely related to the propagation speed of cold pool density flow. In contrast to previous studies, the gust front is caused by the process of rear inflow jet sinking and dry air entrained into downdraught. Moreover, the downdraft forcing due to precipitation particles dragging enhances the intensity of subsidence airflow, resulting in destructive wind with the scale of 10~11. Key words：gust front; vertical inflow structure; cold pool; vertical wind shear; maintenance mechanism 8 q) }. n( f* S+ d( S
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