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2012年春末昆明大暴雨的中尺度对流系统特征分析
梁红丽
(云南省气象台)
Characteristic Analysis of Mesoscale Convective System in the Late Spring 2012 Heavy Rainstorm in Kunming
LIANG Hongli
(Yunnan Meteorological Observatory)
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投稿时间:2017-04-04    修订日期:2018-08-07
中文摘要: 利用常规气象观测资料、NCEP/NCAR逐6h1°×1°再分析资料、FY2E红外云图TBB资料、昆明C波段多普勒雷达探测资料,结合中尺度数值模式的模拟结果,分析了2012年5月24日晚昆明大暴雨期间中尺度对流系统演变特征及形成机理。结果表明,此次大暴雨是在高低空系统最佳配置下产生的。降水峰值出现时,低层增暖湿,从地面到500hPa呈显著的对流性不稳定层结,700~500hPa垂直风切变达14ms-1。纬向结构上,暴雨中心低层东风增强,300hPa以下纬向风辐合,中心强度-28×10-5s-1,150hPa以下上升气流中心强度21ms-1,近地面水汽通量辐合-20×10-5g.hPa-1s-1cm-2;经向上,暴雨中心500hPa以下南风风速辐合,上升气流增强,强度与纬向一致,低层水汽辐合中心强度-30×10-5g.hPa-1s-1cm-2,强于纬向水汽辐合。此外大暴雨中地形对南风的强迫也是显著的,抬升速度在0.4~1.0ms-1之间。再者强降水具有阶段特征,分为初始、加强、回落和衰减四个阶段,昆明近地层浅薄冷空气加强时,引发其东侧对流单体移向昆明,强降水发生;然后南风出现脉动,局地湿层增厚和垂直风切变加大,促使对流单体两度增强并出现降水峰值;第三次峰值则是弱南风脉动及对流单体合并所造成,由于移入的单体较之原地发展的单体弱得多,原地单体作用的降水峰值也明显小于前面两次。对流降水回波属于暖云性质的热带低质心降水回波。
Abstract:Based on conventional meteorological observational data, NCEP/NCAR 1°×1° six hours reanalysis data, the blackbody temperature of FY2E satellite infrared images, C wave band Doppler radar sounding data and simulation results with mesoscale numerical model, a locally heavy rainstorm that occurred in the evening of 24 May 2012 was studied. For the mesoscale convective systems, the evolution characteristics and their formation mechanisms were analyzed in detail. The results showed that the best configuration of upper and low layer systems made the generation of heavy rainstorm. As the peak of precipitation appeared, it increased warm and wet in lower layer, and it presented significantly convectional-unstable stratification from surface to 500hPa, vertical wind shear reached 14ms-1 at 700-500hPa. In zonal structure, easterly enhanced at lower layer in the rain storm center, zonal wind convergenced under 300hPa, and its center intensity was -28×10-5s-1, center intensity of updraft under 150hPa was 21ms-1, convergence of moisture flux at near surface was -20×10-5g.hPa-1s-1cm-2. In meridional, southerly speed convergenced under 500hPa in the rain storm center, then updraft enhanced. Meridional strength was the same as those of zonal. Convergence of moisture flux at in lower layer was -30×10-5g.hPa-1s-1cm-2, which was stronger than that of zonal. In addition, topographic forcing role to south wind was also significant, and lifting speed was 0.4~1.0ms-1. Moreover, heavy rainfall had stage Feature. The evolution of heavy rainfall was divided into four stages, namely, initial, enhancement, fallback and attenuation. While superficially cold air in surface layer over Kunming enhanced, convective cell on its east side moved to Kunming, then heavy rainfall generated. Thereafter, southerly wind pulsated, locally wet layer was thickened, vertical wind shear increased, convective cell enhanced by twice, and precipitation peak appeared. While formation of the third precipitation peak was main in southerly wind pulsating and convective cell complicating, but because volume of incorporation cell was smaller than that of native cell, precipitation peak made by the role of native cell was obvious smaller than those of the other twice. Convective precipitation echo belonged to warm cloud property and had tropics low centroid characteristic.
文章编号:201704040191     中图分类号:    文献标志码:
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
引用文本:
梁红丽,0.[en_title][J].Meteor Mon,():-.
LIANG Hongli,0.Characteristic Analysis of Mesoscale Convective System in the Late Spring 2012 Heavy Rainstorm in Kunming[J].Meteor Mon,():-.