【摘要】 利用常规观测资料以及中尺度数值模式的模拟结果,对2009年8月17—18日山东南部罕见暴雨天气过程成因进行了分析。结果表明:暴雨是受副热带高压、高空西风槽和地面倒槽共同影响产生的;低层强盛的偏南气流建立起水汽通道,把水汽源源不断地向暴雨区输送,同时山东上空低层高温高湿,能量升高,形成上干冷、下暖湿的对流性不稳定层结;强降水产生时,暴雨区上空存在较强的中β尺度系统,该系统具有强而窄的垂直上升运动、上下垂直的辐散辐合结构和强烈的对流不稳定等特征。更多还原

【Abstract】 Based on conventional observational data and mesoscale numerical simulation results,a rare heavy rainfall event occurred in the southern Shandong Province between 17 and 18 August 2009 is analyzed.The results indicate that the rainstorm was influenced jointly by the subtropical anticyclone,the upper-level westerly trough,and the ground inverted trough.The strong south airflow set up the water vapor channel where water vapor can flow to Shandong Province continuously.Meanwhile,the convective unstable stratification was formed over Shandong Province.During the heavy rainstorm process,there was a strong meso-β-vortex system over the rainfall area,which was characterized by strong and narrow vertical ascending motion,a vertical structure with convergence at the lower levels and divergence at upper levels,and strong convective instability.更多还原