华北秋季大暴雨的天气分析与数值模拟

利用常规资料和MM5模拟结果分析了2003年10月10—12日华北地区大暴雨物理成因。分析表明，高层稳定持续的经向环流是大暴雨产生的大环流背景。低空暖切变线和低空急流的直接影响，以及西南涡的加强和日本海高压的阻挡起了重要作用。强烈的上升运动、能量的积累和充沛的水汽输送是大暴雨发生的必要条件。对流层中下层偏南急流、低层的偏东气流和高空的西南急流提供了充足的水汽和能量输送。强涡度柱与强散度区、强上升运动与饱和气柱的互耦，是大暴雨产生的重要机制。强冷空气与强暖湿空气在切变线附近长时间对峙，使大降水持续。这些是形成这次华北地区秋季大暴雨的重要原因。

Numerical Simulation and Analysis of Heavy Rain in Autumn in North China

Based on meteorological observational data and mesoscale numerical model products, the physical mec-hanism of a heavy rain is analyzed. The analysis shows that sustaining meridional circulation at upper levels, low level warm shear line and jets, the strengthening of Southwest vortex and the obstruction from the high pressure on Japanese sea are the im portant reasons of the heavy rain. The main mechanisms are long-time transfer of vapor and energy by various jet streams, and the coupling among the strong vorticity column, violent convergence ascending motion and saturated air column.