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沈杭锋, 章元直, 查贲, 陈勇明, 翟国庆. 梅雨锋上边界层中尺度扰动涡旋的个例研究[J]. 大气科学, 2015, 39(5): 1025-1037. DOI: 10.3878/j.issn.1006-9895.1410.14212
引用本文: 沈杭锋, 章元直, 查贲, 陈勇明, 翟国庆. 梅雨锋上边界层中尺度扰动涡旋的个例研究[J]. 大气科学, 2015, 39(5): 1025-1037. DOI: 10.3878/j.issn.1006-9895.1410.14212
SHEN Hangfeng, ZHANG Yuanzhi, ZHA Ben, CHEN Yongming, ZHAI Guoqing. A Case Study of the Mesoscale Disturbance Vortex in the Boundary Layer on the Meiyu Front[J]. Chinese Journal of Atmospheric Sciences, 2015, 39(5): 1025-1037. DOI: 10.3878/j.issn.1006-9895.1410.14212
Citation: SHEN Hangfeng, ZHANG Yuanzhi, ZHA Ben, CHEN Yongming, ZHAI Guoqing. A Case Study of the Mesoscale Disturbance Vortex in the Boundary Layer on the Meiyu Front[J]. Chinese Journal of Atmospheric Sciences, 2015, 39(5): 1025-1037. DOI: 10.3878/j.issn.1006-9895.1410.14212

梅雨锋上边界层中尺度扰动涡旋的个例研究

A Case Study of the Mesoscale Disturbance Vortex in the Boundary Layer on the Meiyu Front

  • 摘要: 运用实况自动站、高时空分辨率的雷达和数值模拟资料,对2009年7月24日的梅雨锋暴雨过程进行了分析,结果表明:(1)锋面南侧的暖区弱降水环境内,近地面的风场会有扰动涡旋出现,随着扰动涡旋趋于稳定和向上发展,降水迅速加强,形成短时暴雨,并伴随有大风出现。(2)偏西气流从边界层开始发展并加强为急 流,在向东推进的过程中逐渐抬升,形成了一支从边界层倾斜入对流层低层的急流轴;而偏南气流与偏北风相遇之后,不仅形成风向的辐合和切变,而且在空间上被抬升,形成了一支斜升入流。(3)在近地面风场的切变和 辐合作用下,锋生与辐合同步加强,边界层内的涡度也逐渐增强,由此带动了扰动的发生发展,扰动涡旋在边界层内率先形成,随后,在急流的东传和抬升影响下,扰动涡旋也逐步向东移动、向上发展。(4)近地面风速的加强、风向的辐合切变导致了扰动涡旋的发生和形成,并逐渐发展,这是边界层中尺度扰动涡旋发生发展的动力 因子。

     

    Abstract: The heavy rainfall event along the Meiyu front on June 24, 2009 was analyzed using data from auto weather stations, high resolution radars, and simulations. The results show that several surface disturbance vortexes formed after the weak rainfall in the southern warm section of the Meiyu front. With the stabilizing and upward development of the disturbance vortex, a short duration rainstorm accompanied by gale occurred. After the strengthening and lifting of the westerly wind, a westerly jet formed with the jet axis between the planetary boundary layer and the low troposphere. Convergence and shear occurred after the southerly flow encountered the northerly wind. The southerly flow could have turned into convection through lifting by northerly wind. The vorticity of the planetary boundary layer increased gradually followed by synchronous enhancement of frontogenesis and convergence under the influence of surface shear and convergence. Then, the disturbance vortex could form and develop in the planetary boundary layer below the troposphere. The intensification of wind speed, shear, and convergence near the surface were the dynamic factors responsible for the formation of the mesoscale disturbance vortex.

     

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