摘要
运用中尺度非静力模式MM5对2003年梅雨期一次大暴雨天气进行数值模拟,在降雨模拟基本正确的基础上分析暴雨发生原因。结果表明:该次梅雨大暴雨属于切变类暴雨,对流层低层有能量锋区、高层有惯性不稳定活动,暴雨区位于低空急流的左前方、高空急流的右前方。暴雨中心物理量要素的时间—高度演变显示:低层正涡度、辐合,高层负涡度、辐散,深厚的上升运动,等相当位温线抬升,湿位涡及其正、斜压分量3者负值加大均有利于降雨加强;暴雨减弱阶段,这些要素一般向相反方向转变。该次大暴雨的直接影响系统具有明显的中尺度时、空特点,大暴雨的发生与高层惯性不稳定和低层对流不稳定有关。
Withthe meso-scale non-hydrostatic model MM5 ,a heavy rainstorm in the Jiangnan area in the Meiyu peroid of 2003 has been simulated and the formation mechanism of the rainstorm analyzed. Result shows that the rainstorm belonged to a shearline-cansing rainstorm. There were an energy front zone in the low level, and some inertial instable areas in the upper level of troposphere during the torrential heavy rain, and heavy rain took place on the left front side of a low level jet stream, and the right front side of an upper level jet stream. By analyzing the changes of physical quantities with time and height at the rainfall center, it can be seen that the cyclonic vorticity and convergence at the low level, the anticyclonic vorticity and divergence at the upper level, deep upward motion, the lifting of the isolines of equivalent temperature, the magnitude of negative ξmpv, ξmpv1 and ξmpv2 becoming larger were all favorable conditions to the heavy rain. When the rain weakened, almost all these physical quantities went to the opposite. The direct influencing weather systems showed the spatial and temporal features on meso-scale. It was clear that during the heavy rain there existed obvious inertial instability in the upper levels and convective instability in the lower levels.
出处
《南京气象学院学报》
CSCD
北大核心
2006年第6期827-832,共6页
Journal of Nanjing Institute of Meteorology
基金
国家重点基础研究发展计划项目(2004CB4183032004CB418304)
关键词
梅雨暴雨
模拟分析
对流不稳定
惯性不稳定
Meiyu rainstorm
simulation research
convective instability （CI）
inertial instability （II）
