| 摘要: |
| 本文利用常规及加密观测资料、NCEP再分析资料及FY-2G TBB资料,对发生在黔西南州2020年6月23～24日的特大暴雨过程进行了分析,结果如下：此次特大暴雨过程主要由地面弱静止锋触发黔西南北部不稳定能量的大量释放,配合高低空急流、南亚高压,强盛副高稳定维持在黔西南北侧,使得切变南压缓慢,再加上充沛的绝对水汽高效率释放配合外部强水汽辐合,共同造成了此次特大暴雨天气；低层辐合高层辐散及强垂直上升动的特征在强降水发生前表现更为明显,暖式强切变向冷式强切变的转变、正涡度的增大均为局地特大暴雨提供了有力的动力条件,中高层锋面坡度加大、暖湿不稳定层结、能量锋区的南移加之能量的大量释放,为加大降水强度提供了有利的热力条件；地面风场辐合促使初始对流发展,与中低层切变叠加,加剧垂直运动发展,风场辐合出现时间基本提前于强降水时间,根据加密地面风场辐合区位置及其移动的路径可为推断下游强降水的落区提供参考；黔西南北部由于上坡及喇叭口效应,使得气流沿山坡辐合上升,山体使得山前低值系统移动缓慢,增大降水强度；晴隆紫马强降水集中在TBB低值区及云系发展阶段的梯度大值区(非消散阶段),MCS在黔西南维持时间达7个小时；EC暴雨落区与实况更接近,但对大暴雨把握不足,华南中尺度对极端降水的把握明显好于其它数值模式。 |
| 关键词: 黔西南;特大暴雨;天气机理;副高 |
| DOI： |
| 投稿时间：2020-12-17修订日期：2021-01-08 |
| 基金项目: |
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| Meso and small scale characteristics of a subtropical high blocking torrential rain |
| Wang Fen,Meng Qing Yi,Liu Xiang,Wang Xing Ju,Xia Yang |
| (Meteorological Office of Southwest Guizhou;Anshun Meteorological Office;Liupanshui Meteorological Office) |
| Abstract: |
| In this paper, conventional and encrypted observation data,NCEP reanalysis data and FY-2G TBB data are used to analyze the process of heavy rain in the southwest of Guizhou province June 23 ~24,2020. The research results are as follows: this heavy rainstorm was mainly triggered by a large amount of energy which was released by the surface weak stationary front in the northern part of northwestern Guizhou, together with high and low jet stream、south asia high, and strong subtropical high maintained in the northwest of Guizhou which slows down the shear line. Meanwhile, the plentiful absolute water-efficient release with strong external water vapour convergence combined with the above factors have resulted in this heavy rain weather.The characteristics of low-level convergence and high-level divergence are more obvious before the occurrence of heavy rainfall. Strong vertical upward motion of heavy rain center, the transition from warm strong shear to cold strong shear and the increase of positive vorticity both provides strong dynamic conditions for locally heavy rain.The increased front slope of middle and upper levels, warm wet unstable stratification,the southward movement of the energy front area and the massive release of energy, which provides favorable thermal conditions for increasing precipitation intensity. The convergence of surface wind field promotes the development of initial convection, superimposed with low and medium shear,which intensify the development of vertical movement, the convergence time of wind field was earlier than that of heavy rainfall. According to the convergence location of the intensive surface wind field and the moving path, that can provide a reference for inferring the falling area of the downstream heavy rainfall. In the Southwest Guizhou’s north, due to uphill and bell mouth effect,which made the airflow converge and rise along the hillside. The mountain made the low-value system move slowly in front of the mountain,that increasing precipitation intensity. The heavy rainfall in zima of Qinglong is concentrated in the low value area of TBB and the gradient large value area of cloud system development stage (non dissipation stage), the MCS maintains for 7 hours in Southwest Guizhou.The rainstorm area of EC is closer to the actual situation. However, the heavy rain is not well understood, the mesoscale of South China is better than other numerical models for extreme precipitation. |
| Key words: Southwest Guizhou;Heavy rain;Weather mechanism;Subtropical high |
