2013年7月7～11日四川盆地持续性暴雨成因分析

Diagnosis of the Continuous Rainstorm in Sichuan Basin during 7- 11 July 2013

利用逐小时降水资料、Micaps常规气象观测资料、NCEP／NCAR再分析资料以及FY-2E卫星云图资料，探讨了2013年7月7～11日四川盆地西北部出现持续性暴雨的成因。结果表明，暴雨主要是受到稳定少动的副热带高压和季风低压等低纬度地区的天气系统影响，由于这2个系统之间形成的气压梯度力使得南风异常强劲，中尺度东南风低空急流携带着来自孟加拉湾和南海的高温高湿气流与盆地西北边缘的地形相正交，地形抬升配合低空暖式切变线，使得盆地内不断有中尺度的对流云团发展、维持和再生，造成了暴雨的不断发生。此外，对流不稳定能量的集中释放使得暴雨过程中降水集中且时空分布极不均匀。

Abstract A continuous rainstorm process occurred in northwest part of Sichuan Basin during 7 - llth July 2013, and caused severe flood, landslide and great damages. By using hourly precipitation data, Micaps conventional meteorological data, NCEP/NCAR reanalysis data, and FY -2E satellite cloud images, the physical mechanism of the continuous rainstorm process is diagnosed. The resu｜ts show that the steady West Pacific subtropical high and monsoon low arc the two main weather systems of the rainstorm, the southerly wind enhanced because the large pressure gradient between them, thus the southeast low jet formed and brings sufficient water vapor from Bay of Bengal and the South Chi- na Sea to Sichuan Basin, which is orthogonal to the western plateau region. Elevation rise along with the low - level warm shear line led to the development, maintenance and regeneration of the meso - scale convective cloud, which directly caused the persistent rainstorm. Concentrated release of convective instability led to the uneven distribution of rainfall in space and temporal pattern.