河套气旋发展东移与北京721暴雨的关系  

Correlation Between Eastward Developing of Hetao Cyclone and the Severe Rainstorm in Beijing on 21 July 2012

作　　者：孟雪峰 孙永刚[2] 萨日娜 袁慧敏 哈斯[4] 

机构地区：[1]内蒙古自治区气象台,呼和浩特市010051 [2]内蒙古自治区气象局,呼和浩特市010051 [3]内蒙古气象服务中心,呼和浩特市010051 [4]内蒙古包头市气象局,包头市014030

出　　处：《气象》2013年第12期1542-1549,共8页Meteorological Monthly

基　　金：内蒙古科技厅公益项目(突发性气象灾害短临预警系统建设和突发性气象灾害预报方法研究);内蒙古气象局科研项目(短时临近预报预警业务系统)共同资助

摘　　要：对河套气旋发展东移引发的北京2012年7月21日特大暴雨天气过程(简称"北京721暴雨")进行了诊断分析。结果表明:河套气旋是此京721暴雨的直接影响系统,高空辐散区的强迫作用和对流层低阹锋区走向"引导"河套气旋改变了北上的常规路径,迫使其燕尔移直接影响河北、北京地区。河套气旋在滑诂锋区尔移过程中,由暖心正压气旋转变为斜压性气旋,同时,将锋区的辨能转变为动能使河套气旋迅速发展,形成正反馈效应,使得本次暴雨天气过程降水强度自西向东不断增强。河套气旋在北京特大暴雨中的作用表现为:动力抬升、增强水汽输送、触发不稳定能量等三方面。午后,河套气旋暖锋触发不稳定能量释放,在北京地区产生强对流系统,形成中尺度对流辐合体(MCC),使得降水强度成倍增长,是北京地区产生特大暴雨的主要原因,东南气流中地形抬升作用对降水有增幅作用,北京721暴雨是多种有利因素叠加所致。This paper diagnostically analyzes the 721-Beijing rainstorm weather process caused by eastward shift of Hetao cyclone. The results show that. Hetao cyclone is the main impact system on the rainstorm in Beijing on 21 July 2012, and the forcing effect of upper divergence zone and the trend of lower troposphere frontal zone ＂guide＂ the Hetao cyclone to change the conventional path to the north, forcing its eastward shift and directly affecting the region of Hebei and Beijing. In the process of Hetao cyclone＇s moving eastward along the frontal zone, the warm-heart barotropic cyclones change to be baroclinic cy- clones. Meanwhile, the potential energy of frontal zone is changed into kinetic energy to promote the rapid development of the Hetao cyclone, forming a positive feedback effect, and making the intensity of precipitation continuously enhance from west to east. The effects of the Hetao cyclone in the Beijing rainstorm are dynamic lifting, enhancing water vapor transport and triggering unstable energy. In the afternoon, warm front of the Hetao cyclone triggers the release of potential instability energy, generating strong convective system, forming mesoscale convective complexes （MCC） in the Beijing area, and finally, inten- sifying the precipitation further more. There are the main causes of the severe torrential rains in Beijing on 21 July. In addition, the topographic lifting in the southeast airflow strengthens the rainstorm as well. Therefore, this severe rainstorm is caused by a variety of superimposed favorable factors.

关 键 词：河套气旋 特大暴雨 MCC 诊断分析 

分 类 号：P458[天文地球—大气科学及气象学]