【作者】 陈忠明； 何光碧； 高文良； 闵文彬；

【Author】 Chen Zhongming He Guangbi Gao Wenliang Min Wenbin (Chengdu Institute of Plateau Meteorology, Chengdu,610071)

【机构】 成都高原气象研究所；

【摘要】 通过对2004年9月2-6日发生在四川盆地中东部的持续性暴雨过程的诊断分析,揭示了暴雨天气持续的环境场条件、水汽来源、启动和维持机制。主要结果有:(1)台风“桑达”西进,导致大陆高压单体稳定,使沿河西走廊向东南移动的冷槽正好被阻滞于四川盆地北部,为暴雨持续提高了有利的环境条件。(2)南海与孟加拉湾是本次暴雨过程水汽的两个主要源地;850hPa东南低空急流和700hPa西南低空急流的稳定在水汽输送和不稳定大气层结重建方面发挥了重要作用。(3)暴雨过程启动于温湿条件相对均匀(正压特征明显)的暖气团内,大气内部的正压非平衡强迫)是激发本次暴雨过程的主要动力机制。(4)暴雨发生后,能量锋与低空急流的恰当配置,使得能量锋区附近强烈的假相当位温平流梯度,与低空急流附近大的垂直风切变VPv产生耦合相互作用1(se),激发低层气流辐合的维持和增强,是这次持续性强暴雨天气过程的主要维持机制。更多还原

【Abstract】 The diagnostic analysis on environmental fields and water vapour source and excitation mechanism of continuing heavy rain process in Sichuan basin in 2-6 September 2004 are done in this paper. The results show that the stability of atmospheric circulation over Asia and the persistence of synoptic scale trough over Sichuan are benefit to this heavy rain process. The South China Sea and Indian Ocean are water vapour sources of this heavy rain. The low level jets play important role in the transfer of water vapour and the reconstruction of unstable stratification. Heavy rain occurred in warm air mass with uniform temperature and humidity. The unbalanced force of lower atmospheric motion led to occurrence of heavy rain. After occurring heavy rain, the convergence increase trigged by 1 — the coupling reaction between pseudo-equivalent temperature gradient θseand vertical wind shear V Pv is a mechanism of heavy rain maintenance because of just disposition and between low level jet and energy front.更多还原