有限区域分解分析方法在2006年一次东北冷涡暴雨分析中的应用  

The application of wind and water-vapor flux partitioning technique to the structure of a northeast vortex in 2006

作　　者：邓涤菲[1,2] 周玉淑[1] 王东海[3] 

机构地区：[1]中国科学院大气物理研究所,北京100029 [2]中国科学院研究生院,北京100049 [3]中国气象科学研究院灾害天气国家重点实验室,北京100081

出　　处：《地球物理学报》2012年第6期1852-1866,共15页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41075044;41075079;40633016)资助

摘　　要：2006年7月19—24日,东北地区出现一次明显的冷涡发展导致强降水的过程.对这次东北冷涡过程的天气形势分析表明,该东北冷涡的维持和发展与冷涡东部阻塞高压的建立与消亡有关.本文根据500hPa环流形势演变特征,将东北冷涡发生发展过程分为4个阶段,并借助调和-余弦谱展开方法,对东北冷涡各阶段850hPa水平风和水汽通量进行无辐散和无旋转分量分解,分析各阶段无旋转风动能和无辐散风动能之间的能量转化.研究结果表明,分解得到的无辐散风及其水汽通量清楚地展现出了东北冷涡的大尺度环流和水汽输送通道及水汽来源,而从无旋转风及其水汽通量上则可以直观地看到冷涡低层的中小尺度风场及水汽辐合辐散区,为分析东北冷涡内部对流提供帮助.东北冷涡发展的不同阶段其水汽来源有所不同,初始阶段的水汽主要来自黄海和渤海地区,发展阶段水汽主要来自日本海,而到成熟阶段和减弱阶段,水汽输送通道被破坏,冷涡的水汽供应大大减少,与同时期暴雨减弱一致.同时,无旋转风辐合强值区和无旋转风水汽通量大值区的重合区域有利于强对流的发生发展,表现为重合区与TBB(Temperature of Black Body,黑体辐射温度)强对流云带的形状和位置对应良好,与降水落区也较为一致,可为预报东北冷涡引发的强降水落区这一预报难点问题提供参考.从动能转化上看,无旋转风和无辐散风的动能转化项能很好地反映东北冷涡整个生命史过程中各阶段强度的变化特点,对冷涡强度预报具有一定的指示意义.A northeast vortex event happened during 19th to 24th July 2006 in northeast China; the event resulted in heavy rainfall in that area. From the weather situation of the northeast vortex, the maintenance and development of the vortex had strong connection with the buildup and breakdown of blocking high in the east. In the article, the northeast vortex event has been divided into four stages, resorting to the method of harmonic-cosine spectrum expansion, the horizontal wind and water vapor flux have been decomposed into two parts, the results indicate that, on one hand, from the nondivergent wind and its water vapor flux, the large scale circulation and vapor transportation passage have been exhibited intuitively, which can distinguish the source of water obviously, on the other hand, from the irrotational wind component and its corresponding water vapor flux, the convergence and divergence of meso-seale wind and water vapor can be seen directly, moreover, the overlap areas of convergence of strong irrotational wind and the large value of its water vapor flux correspond well to the strong convective cloud and the rainfall areas, therefore, it can be a useful help for the operational precipitation prediction of northeast vortex. From conversion term can well the kinetic energy of nondivergent wind and irrotational wind, the depict the trend of strength during the life cycle of northeast vortex.

关 键 词：东北冷涡 风场和水汽通量场分解 无辐散风 无旋转风 动能转换 

分 类 号：P433[天文地球—大气科学及气象学]