四川一次暴雨天气过程分析
Analysis of Rainstorm Weather Process in Sichuan Province

采用中央气象台提供的自动站数据、欧洲气象中心ECMWF (以下简称EC) ERA5网格距0.25？ × 0.25？再分析数据，国家卫星气象中心的FY-2G卫星的云顶亮温(TBB)资料以及气象站常规气象观测资料等，基于天气动力学诊断法和统计法对2020年8月16日发生在四川的暴雨天气过程进行了研究。结果表明：1) 我国西南地区有一槽，四川盆地位于槽前，受到西南气流的控制，同时，由于副高位置的稳定导致从青藏高原低涡闭合环流分裂出的短波槽持续地对四川盆地产生影响。对流层中低层西南急流的存在，让水汽得以从孟加拉湾–云南–四川这个水汽通道持续地输送过来。为本次暴雨的形成提供水汽条件。2) 冷式切变线的南移将冷空气带进四川盆地，与四川暖湿气流交汇，形成强烈辐合向上抬升大气，提供动力条件。并且低层出现辐合，高层出现辐散的垂直结构诱发抽吸作用也产生了强大的抬升条件。3) 假相当位温垂直剖面图中表明在暴雨发生之前就在34？N以南的地区构成了不稳定层结，累积了不稳定能量。密集且向南弯斜的假相当位温等值线区是不稳定能量释放的主要区域。
Using National Meteorological Centre data, ECMWF (hereinafter referred to as EC) ERA5 0.25？ × 0.25？ reanalysis data, the cloud-top brightness temperature data (TBB) of FY-2G satellite from the national satellite meteorological center and conventional meteorological data of weather station, etc., based on the weather dynamics diagnostic method and statistical method, the process of heavy rain that occurred in Sichuan on August 16, 2020 was studied. And it turns out: 1) There is a trough in the southwest of China. The Sichuan Basin lies in front of the trough and is controlled by the southwest airflow. Meanwhile, the stability of the subtropical high leads to the splitting of the short wave trough from the low vortex closed circulation over the Tibetan plateau. The existence of the mid-lower tropospheric southwest jet stream allows water vapor to be transported continuously from the Bay of Bengal-Yunnan-Sichuan water vapor channel. To provide the water vapor conditions for the formation of this rainstorm. 2) The southward movement of the cold shear line brings cold air into Sichuan Basin, where it converges with the warm and humid air of Sichuan, forming strong convergence and uplifting of the atmosphere, providing the dynamic conditions. In addition, the vertical structure-induced suction with convergence in the lower layer and divergence in the upper layer results in strong uplift conditions. 3) The vertical profiles of pseudo-equivalent potential temperature show that unstable stratification and accumulation of unstable energy were formed in the area south of 34？N before the rainstorm. The dense and southward-curved pseudo-equivalent potential temperature isoline region is the main region for the release of unstable energy.