“03.7”湘西北特大致洪暴雨的触发机制数值研究  

Mechanism Triggering the "03.7" Heavy Rainfall in the Northwest of Hunan Province

作　　者：叶成志[1] 潘志祥 刘志雄 黄小玉 

机构地区：[1]兰州大学大气科学学院,兰州730000 [2]湖南省气象局,长沙410007 [3]娄底市气象台,娄底417100

出　　处：《应用气象学报》2007年第4期468-478,共11页Journal of Applied Meteorological Science

基　　金：国家重点基础研究发展规划项目"我国南方致洪暴雨监测与预测的理论和方法研究"第四课题(2004CB418304);中国气象局武汉暴雨研究所开放基金课题(2004ZD01);中国气象局"十五""预测减灾一体化业务服务系统建设"专项共同资助

摘　　要：利用常规、地面加密观测资料、GMS卫星云图和常德多普勒天气雷达资料,结合MM5中尺度数值模式模拟结果对"03.7"湘西北特大致洪暴雨过程进行综合分析,并探讨其可能的触发机制。研究表明:"03.7"湘西北特大暴雨与边界层内多个中尺度辐合扰动的移动和发展密切相关,且伴随着中尺度雨团的强烈发展,由此诱发的β-中尺度涡旋是此次特大暴雨过程的直接影响系统;有组织的多单体风暴活动是张家界这一特大暴雨中心形成的主要原因;等熵面上的位涡下滑和倾斜涡度的发展可能是导致β-中尺度气旋涡度急剧发展的重要因素;低空急流扰动、对流层高层强辐散形成的抽吸作用以及湘西北特殊地形对此次暴雨过程有明显的触发和增幅作用。The analysis on torrential rain event in Hunan Province on July 7 to 9, 2003 is accomplished. It is the result of the combined use of conventional intensive observational data, GMS satellite cloud picture, Doppler radar data and the numerical simulation result with mesoscale numerical model of the Penn State/NCAR Mesoscale Model 5 （MM5）. In particular, it emphasizes the output based on the observational facts and the MM5 high resolution data. The mesoscale convective system is discovered which is prone to the existence and maintenance of the heavy rainfall center in Zhangjiajie. In order to reveal the development mechanism and spatial structures of Meiyu front rainstorm mesoscale convective systems, some innovative work about this rainstorm triggering mechanism is done. These important scientific conclusions can be used to seek new forcasting ideas, and ultimately improve the heavy rain forecast. The heavy rain is related to the movement and evolvement of multiple mesoscale convergence disturbances. With the rapid development of the mesoscale rain clusters, the β-mesoscale vortex takes shape, by which this torrential rain is directly affected. The reason of this rainstorm is not the severe multi-cell and super-cell. Due to the atmosphere constantly generation of new convective cells and afterwards vanish in the north, the organized multi-cell storm is the main reason of this heavy rain in Zhangjiajie. The appearance of head wind zone about several kilometers above the district of Zhangjiajie which is reflected in the Doppler radar radial velocity field is the result of small-scale cyclone formation and maintenance. It is closely related to the emergence of continuous heavy rain. In the low troposphere layer, as the Southwest jet velocity fluctuates, jet stream flow and the largest northeast nuclear center are split by it and the development of the β-mesoscale vortex in the northwest of Hunan is triggered. The suction effect caused by the low-level jet disturbance and the divergence on the top-level of trop

关 键 词：特大致洪暴雨 β-中尺度气旋 触发机制 

分 类 号：P333.2[天文地球—水文科学] P458.121.1[水利工程—水文学及水资源]