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我国西南地区一次暴雨过程特征及成因
Cause analysis and characteristics of a rainstorm in the southwest area of China
【摘要】 利用卫星云图、多普勒天气雷达资料和高空风等各种天气学资料,对2009年6月8—9日广西、贵州、以及和湖南交界地带的一次暴雨过程进行了综合分析。结果表明,暴雨是由中尺度对流复合体东移、β中尺度强对流云团发展、以及二者合并造成的;地面α中尺度低压带配合α中尺度纬向切变线的生成,为中尺度对流复合体(mesoscale convective complex,MCC)的东移发展、β中尺度强对流云团的发展、以及二者的合并创造了有利条件;地面能量比低值舌的活动是MCC和β中尺度强对流云团生成和发展的触发机制之一;在多普勒雷达径向速度图上,MCC的生成和发展,伴随西南低空急流的建立和维持,大范围的逆风区的生成;MCC的消亡,伴随西南低空急流的减弱和消失,对应西北气流建立和东扩。MCC发展期和β中尺度强对流云团发展期、MCC消散期和β中尺度强对流云团消散期的涡度收支以及视热源和视水汽汇有很大的不同。
【Abstract】 By using the synoptic data such as satellite image,Doppler radar and upper wind,a rainstorm occurring in Guangxi and Guizhou as well as the southwest area of Hunan province on June 8—9,2009 is analyzed.The results show that the storm was caused by the eastward moving MCC(mesoscale convective complex) and the development of β mesoscale strong convective cloud cluster and the mergence of them.The α mesoscale low pressure belt,together with the α mesoscale shear line on the ground surface,provided the conditions for MCC’s movement to the east and β mesoscale strong convective cloud cluster’s development and their mergence.The low tongue of the surface energy ratio was one of the triggers of the generation and development of MCC and β mesoscale strong convective cloud cluster.In the Doppler Radar vertical velocity diagram,the generation and development of MCC was accompanied by the establishment and maintenance of the southeast low jet stream and the generation of wide range of dead wind area.The MCC’s extinction together with the weakening and vanishing southeast low jet stream,were in accordance with the generation and eastward movement of the northwest air stream.Studies also show that the budget of vorticity and the equilibrium of heat and vapour were very different during the development and vanishing periods of MCC and β mesoscale strong convective.
【Key words】 MCC; meso-β scale strong covective cloud cluster; heavy rainfall; vorticity budget;
- 【文献出处】 大气科学学报 ,Transactions of Atmospheric Sciences , 编辑部邮箱 ,2011年06期
- 【分类号】P458.121.1
- 【被引频次】17
- 【下载频次】265