高级检索
张夕迪, 胡艺, 张芳, 等. 2023. 华北地区两次低涡暴雨过程降水特征和成因对比分析[J]. 大气科学, 47(5): 1593−1610. DOI: 10.3878/j.issn.1006-9895.2212.22060
引用本文: 张夕迪, 胡艺, 张芳, 等. 2023. 华北地区两次低涡暴雨过程降水特征和成因对比分析[J]. 大气科学, 47(5): 1593−1610. DOI: 10.3878/j.issn.1006-9895.2212.22060
ZHANG Xidi, HU Yi, ZHANG Fang, et al. 2023. Comparative Study of the Characteristics and Causes of Two Low-Vortex Heavy Rain Events in North China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(5): 1593−1610. DOI: 10.3878/j.issn.1006-9895.2212.22060
Citation: ZHANG Xidi, HU Yi, ZHANG Fang, et al. 2023. Comparative Study of the Characteristics and Causes of Two Low-Vortex Heavy Rain Events in North China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(5): 1593−1610. DOI: 10.3878/j.issn.1006-9895.2212.22060

华北地区两次低涡暴雨过程降水特征和成因对比分析

Comparative Study of the Characteristics and Causes of Two Low-Vortex Heavy Rain Events in North China

  • 摘要: 本文利用多种观测资料和ERA-5再分析资料对2021年7月11~13日(过程1)和2016年7月19~21日(过程2)华北地区两次低涡暴雨过程的降水特征和成因进行了对比分析。结果表明:这两次暴雨过程均发生在南亚高压东伸加强、副热带高压西伸北抬、中纬度西风带低涡系统东移北上发展、下游高压坝稳定维持的环流背景下,但过程1的累计雨量、降雨强度、影响范围、持续时间和极端性均不及过程2。两次过程的低空急流差异明显,过程1以低涡南侧的西南急流为主,过程2不仅西南急流更强,低涡北侧的偏东风急流同样显著,低层偏东风在太行山东麓地形的作用下产生了更明显的强降水。两次过程的低涡强度、结构及路径存在明显差别,过程1的低涡发展较为浅薄,仅在对流层中低层存在明显的正涡度,且在过程后期移动速度较快,一路沿太行山北上并最终在河北北部消散;而过程2的低涡更为深厚,后期在河北西南部稳定少动直至消散。两次过程的阶段性发展特征也存在一定差异,在第一阶段,过程1的低层辐合主要出现在低涡中心附近的山西南部至河南北部,而过程2的辐合主要出现在低涡北侧偏东风急流与地形交界处的河北西部地区;在第二阶段中,两次过程均出现了类似于台风螺旋雨带结构的低涡螺旋型对流雨带,但过程1主要出现在低涡东侧,而过程2主要发生在低涡北侧,这可能是由于水平涡度旋度、差动垂直涡度平流、暖平流以及非绝热加热的分布差异导致的;在第三阶段,过程1的低涡已移至华北北部,低涡中心附近的强辐合配合不稳定层结和地形抬升产生了较强降雨;而过程2的低涡仍然位于河北西部,低涡东北侧的暖切变辐合不及过程1,但对流不稳定层结更深厚,从而产生了更强的垂直上升运动及更强的降雨。上述结论有助于理解两次暴雨过程的时空分布和强度差异及可能成因。

     

    Abstract: In this work, the characteristics and causes of two low-vortex heavy rain events in North China on July 11–13, 2021 (Event 1) and July 19–21, 2016 (Event 2) were analyzed using multiple observations and ERA-5 reanalysis. Both events took place under similar background circulations: the eastward movement and strengthening of the South Asian high, the westward and northward movements of the subtropical high, the eastward and northward movements and development of the mid-latitude vortex, and the stable maintenance of the downstream high-pressure dam. However, Event 1 was inferior to Event 2 in terms of accumulated rainfall, rainfall intensity, influence area, duration, and extremity; furthermore, their low-level jets (LLJ) were also different. In Event 1, southwest wind dominated the LLJ and was mainly located at the south of the low vortex, while in Event 2, the southwest jet was stronger than Event 1, and the easterly jet to the north side of the vortex was more significant than Event 1. Moreover, this easterly jet generated heavier precipitation under the influence of topography at the eastern foot of the Taihang Mountains. In addition, the two events’ vortex intensity, structure, and path were different. In Event 1, the vortex was shallow, and the positive vorticity was mainly located at the middle and lower troposphere. It moved faster in the later stages of Event 1 northward along the Taihang Mountains and eventually dissipated in North Hebei. However, in Event 2, the vortex was deeper and rarely moved in Southwest Hebei until it dissipated. The stage characteristics of these two events were also different. In the first stage, the low-level convergence of Event 1 mainly happened in South Shanxi and North Henan, which is near the vortex center, while the convergence of Event 2 mainly occurred at the junction of the easterly jet and terrain on the north side of the vortex in West Hebei. In the second stage, both events presented low-vortex spiral-shaped convective rainbands that looked like spiral rainbands in the typhoon. These spiral rainbands mainly appeared to the east of the low vortex in Event 1, whereas to the north of the low vortex in Event 2. This may be due to the different distribution of the curl of horizontal vorticity, differential vertical vorticity advection, warm advection, and diabatic heating. In the third stage, the vortex of Event 1 moved to the northern part of North China, and the strong convergence of the horizontal winds under an unstable environment and topographic lifting near the vortex center produced heavy rainfall. Meanwhile, the vortex of Event 2 continued to be located in West Hebei. Although the warm shear convergence on the northeast side of the vortex was not as strong as that in Event 1, the convectively unstable stratification was deeper, leading to a larger vertical upward movement and rainfall. This work would provide a reference for understanding the spatial and temporal differences between the two heavy rain events and their possible causes.

     

/

返回文章
返回