【作者】 王颖；

【导师】 周军； 寿绍文；

【作者基本信息】 南京信息工程大学 ， 气象学， 2006， 硕士

【摘要】 本文从水汽方程出发,推导新构造的诊断量—水汽螺旋度方程,并讨论了其随时间变化的影响因子。利用MM5中尺度数值模式模拟三个暴雨过程,在模式输出结果可靠的基础上研究水汽螺旋度和暴雨的关系。发现水汽螺旋度的相对增大都伴有降水的相对增幅,且其中心区与和暴雨过程相关的低空急流有很好的对应。 详细分析2004年6月24日的暴雨过程,采用NCEP1°×1°的再分析资料以及地面和高空的常规观测资料对这次降水过程的影响系统及其可能机制进行了初步分析,发现中高纬度两槽一脊的形势是这次暴雨发生的大尺度环流特征;干冷、暖湿的空气在江淮地区交锋、梅雨锋上的中尺度辐合线、850hPa上的低涡、切变线以及西南低空急流都是导致这次暴雨的影响系统;另外,该地区存在高能、饱和的不稳定环境,也有利于大暴雨的产生。 使用模式输出结果分别利用本文输出的两个诊断量即:螺旋度通量散度和湿螺旋散度以及前人常用的螺旋度算法诊断了这次暴雨过程,分析了造成它们之间不同诊断结果的原因。另外,也比较了两种计算湿螺旋散度的方法,得到了在降水不同时期应使用不同湿螺旋散度算法进行诊断的结论。更多还原

【Abstract】 A new diagnostic quantity —moisture helicity is deduced from moisture equation, and its influence factors with time are analyzed in details by the diagnostic analysis . The mesoscale numerical model （MM5V3） is used to simulate three heavy rain processes .With successfully the processes be simulated, the model output with high spatial and temporal resolutions are used to study the relation on moisture helicity and heavy rainfall .The results show that with the moisture helicty raising, the precipitation is up .Additionally, the areas of them are correlative well, which is the moisture helicity is corresponding better with the low level jet of southeast.A heavy rain occurred in Changjiang basins on 24^th June 2004 are studied in detail. Based on NCEP realayzed data with the spatial precision 1° × 1° and other observational datasets, two troughs and one ridge are the characteristics of macroscale in the study to the influential systems and mechanism of this process. The conflict of the dry、 cold masses and the warm、 wet masses ,mesoscale convergence on Meiyu front ,low eddy ,shear line and stably maintaining of low jet make for the rainfall.The condition of high energy and saturation benefits for the form of this rainfall.Two diagnostic variable named as helicity flux divergence and humid helical divergence in this paper are used to diagnose the heavy rain .In addition,the helicty used widely before is also contrasted with the two in this paper. There are two arithmetic of humid helical divergence being compared as well. The results show that we should use different diagnostic variable in different period of heavy rainfalls.更多还原