摘要
2004年9月初,四川省东北部和重庆地区出现了大范围的持续性暴雨和大暴雨天气过程。对这次暴雨过程的持续性原因及其与低涡的关系诊断分析结果表明,(1)8月底从孟加拉湾向东北传播的西南季风的低频振荡使大量来自热带洋面的暖湿空气向四川盆地输送,从青藏高原不断有短波槽东移到盆地上空,使干冷空气和暖湿气流不断在盆地的东部交汇,为持续性暴雨的发生提供了稳定的环流背景和充足的水汽;(2)中尺度对流云团的强烈发展导致强降雨的发生,当中尺度对流系统合并发展为中α尺度低涡后,低涡的发展引起更强的辐合上升运动,为暴雨的持续发生提供了持续的上升运动和有利的中尺度环境场;(3)对流层低层的暖平流和对流层中层的正涡度平流的维持使低涡持续发展。
A persistent heavy rainfall event struck the northeast part of Sichuan and Chongqing during 2—6 September 2004. The meteorological reason and the relationship between heavy rains and the vortex in the lower-reaches of the Jialing River are analyzed. It is shown that in the east part of the Sichuan Basin, the convergence of the easterly propagating trough from the Tibetan Plateau and warm moisture from the Bengal Bay by Lower Frequency Oscillation (LFO) of the South Asian summer monsoon provides stable large-scale background and fluent moisture for the persistent heavy rains, that strongly development of meso-scale convective systems (MCSs) initiating the rainstorms and the MCSs combining into meso-α-scale vortex provides persistent lifting and available meso-scale background for lasting heavy rains, that warm advection in the lower troposphere and positive vorticity advection in the middle troposphere take advantage of the vortex development.
出处
《气象》
CSCD
北大核心
2005年第5期37-41,共5页
Meteorological Monthly
基金
"973"国家重点基础研究发展规划项目2004CB418300资助
