【摘要】 采用实测资料对 2 0 0 2年 6月 8～ 9日陕南大暴雨过程进行分析后认为 :除了有利的大尺度条件之外 ,β中尺度天气系统的发生发展是造成本次强暴雨的最直接原因 ,这类系统的发生发展具有很强的局地性和突发性。分析表明 ,对流层中低层水汽的大量集中以及对流不稳定条件的存在可能对此类系统发展提供了有利环境 ,对其启动的机制作了初步的讨论 ,认为地形的动力强迫和地面冷锋以及低空急流扰动可能对此类系统的发生发展起了触发作用。更多还原

【Abstract】 By using observational data, weather system causing severe heavy rain in the southern part of Shaanxi Province during 8-9 June 2002 is analyzed. It is found that meso-β scale weather systems with highly local and explosive features occurred and developed in the southern part of Shaanxi Province which is the direct reason for severe heavy rainfall in this area apart from favorable large-scale conditons. Results show that existence from strong convergence of water vapor and the conditional convective instability in the middle and low troposphere probably provided the suitable environment for heavy rainfall. In addition, the triggering mechanism of mesoscale systems is discussed and results imply that the dynamical forcing of terrain, surface cold front and mesoscale disturbance of low-level jet may play important triggering role.更多还原