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梁维亮, 翟丽萍, 农孟松, 李向红. 2019: 广西一次深秋暴雨过程降水时空差异成因分析. 暴雨灾害, 38(1): 7-16. DOI: 10.3969/j.issn.1004-9045.2019.01.002
引用本文: 梁维亮, 翟丽萍, 农孟松, 李向红. 2019: 广西一次深秋暴雨过程降水时空差异成因分析. 暴雨灾害, 38(1): 7-16. DOI: 10.3969/j.issn.1004-9045.2019.01.002
LIANG Weiliang, ZHAI Liping, NONG Mengsong, LI Xianghong. 2019: Analysis on the spatiotemporal difference of rainfall in a Guangxi late autumn rainstorm event. Torrential Rain and Disasters, 38(1): 7-16. DOI: 10.3969/j.issn.1004-9045.2019.01.002
Citation: LIANG Weiliang, ZHAI Liping, NONG Mengsong, LI Xianghong. 2019: Analysis on the spatiotemporal difference of rainfall in a Guangxi late autumn rainstorm event. Torrential Rain and Disasters, 38(1): 7-16. DOI: 10.3969/j.issn.1004-9045.2019.01.002

广西一次深秋暴雨过程降水时空差异成因分析

Analysis on the spatiotemporal difference of rainfall in a Guangxi late autumn rainstorm event

  • 摘要: 利用地面和高空观测资料、自动站观测资料、多普勒天气雷达观测资料和NCEP的FNL再分析资料对2015年11月20日广西一次深秋暴雨过程进行天气学诊断,并对过程中降水时空差异做成因分析。结果表明:暴雨过程发生在副热带高压位置偏西偏北,低层大气偏暖偏湿的异常气候背景下。暴雨过程中降水时空特征存在差异:北部雨强较小,降水时间长,暴雨落区集中;南部雨强较大,暴雨落区分散,雨带多处断裂。北部条件性对称不稳定层结造成带状回波强度比南部条件不稳定环境下的飑线强度弱,而持续时间长。北部是强水汽辐合区,湿层深厚,偏南气流的水汽输送对降水维持有重要作用;南部"上干下湿"结构有利于近地层辐散气流加强以及飑线移速加快。北部风向垂直切变小,造成带状回波后向传播,"列车效应"造成长时间降水;南部风向垂直切变大,导致飑线右向传播,视觉上表现为飑线快速东移和"跳跃式"东移。背景环流和要素分布差异使广西北部和南部中尺度对流系统的发展特征不同,最终导致降水时空差异。

     

    Abstract: The spatiotemporal difference of rainfall in a late autumn rainstorm event in Guangxi on 20 November 2015 was analyzed using data from the ground, sounding, automatic weather station and Doppler radar observations and NCEP FNL reanalysis. The results show that the rainstorm was developed under a warm and wet climatologically anomalous condition, when the subtropical high was further westward and northward. The spatiotemporal characteristics of rainfall are different. The rainfall in north Guangxi was sustained and concentrated, and the rainfall in the south was more torrential, transitory and discrete. Conditional symmetric instability in north Guangxi led to weaker and more sustained convections than under the condition unstable stratification in the south. The vapor flux convergence was intensive in the north and the moist layer is deep. The vapor flux caused by southerly was important to sustain the rain. The upper dry and low moist stratification caused the strengthened downdraft and the accelerated squall line in the south. Wind direction vertical shear in north Guangxi is small, which caused the multi-cell storm propagated backward. Train effect led to sustained rainfall. In the opposite, the squall line propagated rightward, moved easterly rapidly or suddenly in the south. The difference in background circulation and element distribution caused the different characteristics of mesoscale convective systems, finally led to the spatiotemporal difference of rainfall.

     

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