一次源于高原东侧低涡的江淮气旋形成及结构分析  

AN ANALYSIS ON THE GENERATION AND STRUCTURE OF A CYCLONE OVER YANGTZE-HUAIHE RIVER VALLEYS ASSOCIATED WITH THE VORTEX ON THE EAST SIDE OF TIBETAN PLATEAU

作　　者：陈永林[1] 曹晓岗[1] 刘敏[1] 王慧[1] 

机构地区：[1]上海中心气象台,上海200030

出　　处：《热带气象学报》2013年第5期793-802,共10页Journal of Tropical Meteorology

基　　金：国家科学技术部(2005BA908B15);上海市科委基金项目(05DZ05815)共同资助

摘　　要：利用常规天气图和T639分析资料,对2010年5月一次江淮气旋的形成及结构进行详细研究.结果表明,本次江淮气旋形成前,在青藏高原东侧的川、黔地区活动着准静止短波系统（500 hPa短波槽、700 hPa 和850 hPa气旋性辐合环流）.当青藏高原北支槽从500 hPa输送正涡度、干冷空气,南支槽从700hPa和850hPa输送正涡度、暖湿空气进入导致准静止短波系统活跃并发展东移至长江下游时,向下伸展至地面向上伸展至高空,最终形成庞大深厚的温带气旋.其减弱过程与发展过程正好相反,先从高空开始减弱,然后地面减弱,最后低空低压环流消失.江淮气旋的形成阶段,中心垂线倾斜度≥60 °；在发展过程中上下层低压中心逐渐靠近,成熟阶段垂线倾斜度缩小至≤80 °.分析地面～200hPa江淮气旋环流特征还发现,其外围直径是地面和低空大而高层小.水平风速则是低空大而地面和高层小.本个例的形成过程与已有研究的主要区别在于：经典模式温带气旋形成于一条温度或密度的不连续的锋面上,Petterssen模式由低层向高层自下而上发展,而本例最先形成于低空,然后向地面和上空伸展.Using the synoptic charts and T639 numerical model data,an analysis was conducted to probe the generation and structure of an extratropical cyclone over Yangtze-Huaihe river valleys during late May,2010.Some facts reveal that this cyclonic circulation begins at levels 700 to 850 hPa.There are quasi-static short waves over Sichuan and Guizhou provinces before the cyclone are formed.As a northern branch trough moves eastwards at 500 hPa with positive vorticity advection and dry air,another southern branch trough moves eastwards at 700 and 850 hPa at the same time,bringing positive vorticity and moisture into this region.Both conditions activate quasi-static short waves and a cyclone develops and extends downward to the surface and upward to 500 hPa or even higher and finally becomes a large-sized,deep extratropical cyclone.This extratropical cyclone decreases with a reserve procedure; first,the aloft system weakens,followed by surface systems,and then a lower-level low becomes extinct.The results also show that a） the spinning cyclone axis leans significantly with height during its formation,but it becomes almost vertical during the mature period,b） the size of the cyclone is larger at lower levels than at upper levels,and c） wind speed is also stronger at lower levels than at upper levels.This process of extracyclogenesis is distinguished from the classical theory in which an extratropical cyclone is formed first at lower levels and develops upward in accordance with the Petterssen model.But in this case it is formed at lower levels first but develops both downward to the surface and upward to upper levels.

关 键 词：江淮气旋 青藏高原 初始环流 气旋垂线 结构 

分 类 号：P447[天文地球—大气科学及气象学]