西藏林芝地区一次暴雨过程的中尺度模拟与分析

利用常规观测资料、FY-2E卫星观测的TBB资料,对2015年8月19日发生在林芝地区的一次暴雨过程进行天气分析,并利用中尺度数值模式WRF的模拟结果分析此次暴雨过程中尺度系统的结构特征。结果表明,此次暴雨过程发生在高原低涡切变的环流形势下,伴随辐合线发展的线状对流系统是此次暴雨发生的主要原因。WRF模式可较好地模拟出暴雨过程的环流形势和降水的落区、量级。西南风引导的暖湿气流为暴雨的发生、发展提供充沛的水汽条件;对中尺度结构的分析表明,低层辐合、高层辐散的结构以及在降水区存在的正涡度伴随强烈的上升运动为此次暴雨过程提供了有利的动力条件,假相当位温的分布能够为暴雨提供有利的热力条件,垂直螺旋度低层正中心的配置反映出大气的不稳定分布,有利于中尺度对流系统的发展与维持。

Numerical simulation and diagnostic analysis of rainstorm in the Tibetan Plateau

The synoptic analysis of a rainstorm event was occurred in Linzhi area on August 19, 2015. was analyzed using conventional observations and TBB satellite data. The mesoscale numerical model WRF is used to simulate the precipitation process and analyze the structural characteristics of the mesoscale system. The results indicates that Rainstorm process is formed under beneficial large-scale circulation background, Occurs in the circulation situation of a shear line which is formed between Iran high pressure and deputy high pressure, The linear convective system with the development of convergence line is the main reason for the rainstorm. WRF model has simulated this heavy rainstorm event quiet well, such as precipitation area and magnitude, Warm and humid air guided by southwest wind provides abundant water vapor conditions for rainstorms, Analysis of mesoscale structure, Low-level convergence, high-level divergence and strong upward motion provide dynamic conditions for the occurrence and development of this rainstorm process. Distribution of vertical helicity can reflect atmospheric instability, Favorable to the development of convection.