广西一次深秋暴雨过程降水时空差异成因分析
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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。
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.
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.
引文
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[12] Emanuel K A. The Lagrangian Parcel Dynamics of Moist Symmetric Instability[J]. Journal of the Atmospheric Science, 1983, 40(10):2 368-2 376
[13]段玮,肖子牛,周泓.一次典型川滇切变线暴雨过程的诊断分析[J].暴雨灾害,2017,36(3):200-206
[14]孙继松.短时强降水和暴雨的区别与联系[J].暴雨灾害,2017,36(6):498-506
[15]鲍旭炜,谈哲敏.二维多单体雷暴系统中对流单体生成和发展的新机制[J].气象学报, 2010,68(3):296-308
[16]孙继松,何娜,王国荣,等.“7.21”北京大暴雨系统的结构演变特征及成因初探[J].暴雨灾害, 2012,31(3):218-225
[17]孙继松,何娜,郭锐,等.多单体雷暴的形变与列车效应传播机制[J].大气科学, 2013,37(1):137-148
[18]俞小鼎.短时强降水临近预报的思路与方法[J].暴雨灾害,2013,32(3):202-209
[2]黄翠银. 2010年1月广西冬季暴雨水汽特征分析[J].气象研究与应用,2011,32(4):20-22
[3]张芳华,陈涛,杨舒楠,等.一次冬季暴雨过程中的锋生和条件对称不稳定分析[J].气象,2014,40(9):1 048-1 057
[4]黄翠银,陈剑飞.2013年12月广西一次暴雨落区变化原因分析[J],气象研究与应用,2014, 35(1):29-35
[5]金琪,谌伟.对湖北省2002年一次秋季暴雨天气过程的分析[J].暴雨灾害,2003,22(3):22-25
[6]范俊红,郭树军,王世彬,等.一次秋季暴雨天气成因分析[J].气象,2005,31(9):62-65
[7]魏东,杨波,孙继松.北京地区深秋季节一次对流性暴雨天气中尺度分析[J].暴雨灾害,2009, 28(4):3-8
[8]王秀明,俞小鼎,周小刚.雷暴潜势预报中几个基本问题的讨论[J].气象,2014,40(4):389-399
[9]徐明,赵玉春,王晓芳,等.华南前汛期持续性暴雨统计特征及环流分型研究[J].暴雨灾害,2016,35(2):109-118
[10] Moore J T, Lambert T E. The Use of Equivalent Potential Vorticity to Diagnose Regions of Conditional Symmetric Instability[J]. Weather and Forecasting,1993,8(3):301-308
[11]费建芳,伍荣生,宋金杰.对称不稳定理论的天气分析与预报应用研究进展[J].南京大学学报(自然科学版),2009,45(3):323-333
[12] Emanuel K A. The Lagrangian Parcel Dynamics of Moist Symmetric Instability[J]. Journal of the Atmospheric Science, 1983, 40(10):2 368-2 376
[13]段玮,肖子牛,周泓.一次典型川滇切变线暴雨过程的诊断分析[J].暴雨灾害,2017,36(3):200-206
[14]孙继松.短时强降水和暴雨的区别与联系[J].暴雨灾害,2017,36(6):498-506
[15]鲍旭炜,谈哲敏.二维多单体雷暴系统中对流单体生成和发展的新机制[J].气象学报, 2010,68(3):296-308
[16]孙继松,何娜,王国荣,等.“7.21”北京大暴雨系统的结构演变特征及成因初探[J].暴雨灾害, 2012,31(3):218-225
[17]孙继松,何娜,郭锐,等.多单体雷暴的形变与列车效应传播机制[J].大气科学, 2013,37(1):137-148
[18]俞小鼎.短时强降水临近预报的思路与方法[J].暴雨灾害,2013,32(3):202-209
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