江苏梅汛期暴雨高空能量输送及高低空要素耦合特征

利用2003-2005年梅汛期江苏15个区域性暴雨个例的NCEP再分析资料,计算了30°-40°N涡旋角动量,从宏观角度上分析了高空能量变化与江苏暴雨之间的关系,并在此基础上进一步从上下层配置和物理量定量诊断分析了江苏暴雨预报着眼点。利用2006—2009年6-7月江苏17个暴雨和非暴雨个例,诊断分析了不同区域出现暴雨的流场和不同层次的物理量。结果表明:(1)角动量的输送和江苏暴雨有一定的变化规律。(2)高空急流带、南亚高压位置与低空西南急流对暴雨及其非暴雨的产生和落区有明显的预报作用,建立了不同区域出现暴雨的概念模型。(3)暴雨和非暴雨的物理量耦合存在明显的差异。当高层散度值在(1～2)×10-5s-1以上,低层涡度在3×10-5s-1以上,上升速度在(3～4)×10-3hPa.s-1以上,产生暴雨的概率较大。能量输送特征、概念模型的建立和物理量指标的确定为江苏梅汛期暴雨的提前预报提供了新的预报思路和量化参考依据。

Characteristics of Upper Energy Transport and Coupling of Meteorology Elements on Upper and Lower Levels during Rainstorm Process in Meiyu Season of Jiangsu

Focusing on fifteen regional rainstorm events during the flood seasons of 2003-2005 in Jiangsu in which South Asia High moved northward and extended eastward,the transportation spectrum of angular momentum in 30°-40°N was calculated the relation between upper-level energy changes and rainstorm in Jiangsu Province and was macroscopically analyzed.The upper- and lower-level structure and physical quantity quantitative forecast points in Jiangsu were diagnosed and analyzed,through calculating mean field,flow fields of rainstorm in different regions and different physical quantities by closely studying 17 rainstorm and non-rainstorm processes in Jiangsu during June and July of 2006-2009.The results show that the angular momentum transport has the close relation with rainstorm in Jiangsu,and the upper-level jets,the position of South Asia High and lower-level southwest jet to the rainstorm and non-rainstorm occurring and its rainfull area have obvious forecast effect,which helps to establish conceptual models of rainstorms in different regions, and the physical quantity coupling between rainstorms and non-rainstorm has obvious differences. When the upper divergence value is above(1~2)×10~-5s~-1,and lower vorticity is above 3×10~-5s~-1 and ascending velocity is above(3~4)×10~-3hPa·s~-1,the probability of occurring rainstorm is the characteristics of high energy transportation,conceptual model and physical quantity provide the new forecast points and quantitative reference for the accurate forecast of rainstorm in Meiyu season of Jiangsu.