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投稿时间：2017-04-04 修订日期：2018-08-07
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6 h 1°×1°再分析资料、FY 2E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500 hPa呈显著的对流性不稳定层结，700～500 hPa垂直风切变达14 m·s-1。纬向结构上，暴雨中心低层东风增强，300 hPa以下纬向风辐合，中心强度为-28×10-5 s-1，150 hPa以下上升气流中心强度为21 m·s-1，近地面水汽通量辐合为-20×10-5 g·hPa-1·s-1·cm-2；经向上，暴雨中心500 hPa以下南风风速辐合，上升气流增强，强度与纬向一致，低层水汽通量辐合中心强度为-30×10-5 g·hPa-1·s-1·cm-2，强于纬向水汽通量辐合。此外大暴雨中地形对南风的强迫也是显著的，抬升速度在0.4~1.0 m·s-1。这次强降水分为初始、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。
中文关键词: 局地大暴雨，γ中尺度对流系统，结构特征，触发因子，地形
Abstract:Based on conventional meteorological observational data, NCEP/NCAR 1°×1° 6 h reanalysis data, the blackbody temperature of FY 2E satellite infrared images, C 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 is studied. For the mesoscale convective systems, the evolution characteristics and their formation mechanisms are analyzed in detail. The results show that the best configuration of upper and low layer systems made the generation of heavy rainstorm. As the peak of precipitation appeared, the lower layer became warmer and wetter, significantly convectional unstable stratification from surface to 500 hPa appeared, and vertical wind shear reached 14 m·s-1 in 700-500 hPa. In zonal structure, easterly enhanced at lower layer in the rainstorm center, zonal wind convergenced under 300 hPa, and its center intensity was -28×10-5 s-1, center intensity of updraft under 150 hPa was 21 m·s-1, convergence of moisture flux near surface was -20×10-5 g·hPa-1·s-1·cm-2. In meridional direction, southerly speed convergenced under 500 hPa in the rainstorm center, then updraft enhanced. Meridional strength was the same as those in zonal direction. Convergence intensity of moisture flux at lower layer was -30×10-5 g·hPa-1·s-1·cm-2, 〖JP2〗stronger than that of zonal intensity. In addition, 〖JP〗topographic forcing affected south wind significantly, and the lifting speed was 0.4-1.0 m·s-1. Moreover, heavy rainfalls were different in the four stages, namely, initial, enhancement, fallback and attenuation. While 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, local wet layer was thickened, vertical wind shear increased, convective cell enhanced twice, and precipitation peak appeared. The formation of the third precipitation peak was mainly caused by southerly wind pulsating and convective cell complicating, but because volume of incorporation cell was smaller than that of local cell, precipitation peak created by the local cell was obvious smaller than the peaks in the previous ones. Convective precipitation echo belonged to warm cloud property and had tropics low centroid characteristic.
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基金项目:国家自然科学基金项目（41365007和41365006）、中国气象局预报员专项（CMAYBY2018 070）和云南省科技惠民专项(2016RA096)共同资助
引用文本：
梁红丽,王曼,李湘,2018.2012年春末昆明大暴雨的中尺度对流系统特征分析[J].气象,44(11):1391-1403.
LIANG Hongli,WANG Man,LI Xiang,2018.Characteristic Analysis of Mesoscale Convective System of Heavy Rainstorm in Kunming in the Late Spring 2012[J].Meteor Mon,44(11):1391-1403.
梁红丽,王曼,李湘,2018.2012年春末昆明大暴雨的中尺度对流系统特征分析[J].气象,44(11):1391-1403.
LIANG Hongli,WANG Man,LI Xiang,2018.Characteristic Analysis of Mesoscale Convective System of Heavy Rainstorm in Kunming in the Late Spring 2012[J].Meteor Mon,44(11):1391-1403.
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