2008年7月黄淮暴雨过程中西南涡结构特征分析
The analysis on the structure characteristics of the Southwest Vortex in a rainstorm eventin July 2008 over Huanghuai valley
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摘要: 对西南涡暴雨的预报不仅取决于对西南涡移动路径的把握，也与西南涡的结构及其演变密切相关。利用NCEP/NCAR 1毅伊1毅逐6 h再分析资料，对2008年7 月一次东移影响黄淮的西南涡的结构特征和暴雨机理进行分析，结果表明：西南涡的生成过程包含高原涡的耦合诱发，西南涡的生成、发展与干位涡向对流层低层扰动下传有关；中高纬冷空气与副热带高压边缘暖湿气流对峙加强了系统的斜压性，使西南涡中心向上伸展的位涡柱和正涡度柱具有向西倾斜的结构；成熟的西南涡具有中尺度非对称的显著斜压结构特征；对流层中层正涡度平流是西南涡发展和引导西南涡移动的重要因素；凝结释放大量潜热促使低层西南低涡发展，使降水增强。Abstract: The forecast of heavy rain induced by vortex is not only determined by the vortex movement track, but also closely related to its structure and revolution. Based on NCEP/NCAR 1°×1° 6-hourly reanalysis data, the structure characteristics of southwest vortex and the mechanism of heavy rain in July 2008 are analyzed. The results show that the producing process of southwest vortex includes the coupling and induction of Tibetan Plateau vortex,and the generation and development of southwest vortex are related to the disturbance transmits of dry potential vorticity downwards to the lower troposphere. The confrontation of cold air from middle-high latitude and warm-wet air along the edge of the sub-tropic high strengthens baroclinicity of the system, which makes the potential vorticity column and positive vorticity column over the vortex center incline westward with height. The mature southwest vortex is with meso-scale asymmetric significantly baroclinic structure. The positive vorticity advection in the mid-troposhere is an important factor which makes southwest vortex develop and move. The condensation heating make southwest vortex develop and enhance the precipitation
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Keywords:
- hwest vortex /
- dynamic structure /
- heavy rain /
- potential vorticity /
- condensation latent heat
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