2008年云南滇中秋季罕见连续强降水过程诊断

Analysis of Autumn Rare Continuous Intensive Precipitation Process of 2008 in Central Section of Yunnan Province

对2008年秋季(10月24日～11月5日)云南滇中秋季罕见连续强降水过程的环流背景和物理量场进行诊断。结果表明,低层冷锋切变、中高层辐合区维持是造成此次云南滇中秋季罕见连续强降水的主要天气形势背景;来自孟加拉湾和中南半岛南部的2支水汽在云南中南部汇合,形成深厚的水汽辐合带;暖湿气流沿低层冷空气向上爬升,形成长时间的上升运动,对这次强降水天气过程的维持起着重要作用;连续强降水中心与对流有效位能CAPE弱高值区具有较好的对应指示性;强降水过程期间,冷锋切变云带上共有5个中尺度云团生成。

Based on the NCEP reanalysis and conventional observation information,the circulation background and physical field of the rare continuous intensive precipitation process occurred in autumn（from October 24 to November 5）of 2008 in central section of Yunnan province were analyzed and diagnosed.The results showed that the low-level cold front shear convergence with the two high-pressure high-level,which has stable and less dynamic,is the main synoptic situation background of this autumn rare continuous intensive precipitation in central section of Yunnan Province.The two water vapor from the Bay of Bengal and the south of Indo China along the subtropical peripheral southerly flow transport constantly,converging in the south central of Yunnan and forming a more deep moisture convergence zone;warm and humid air along the low-level cold air upwards,forming upward motion,the cold advection of troposphere top sending down constantly,enhancing the stationary front and playing an important part in keeping the cold air on the ground.The continuous intensive precipitation is located on the weak high-value areas of CAPE,playing a better directed role on the drop zones for storm;during the heavy precipitation,there are five meso-scale cloud generate in the cold wind shear cloud belt.In this favorable context of large-scale circulation,frequent movement of the mesoscale system is the direct cause of this continuous intensive precipitation process.