刘柯,毛江玉,汪小康,生宸,张冠舜,任靖. 2024. 2021年7月20—22日豫北地区暴雨过程中尺度低涡和垂直运动发展的位涡动力学诊断. 气象学报,82(3):306-318. DOI: 10.11676/qxxb2024.20230072
引用本文: 刘柯,毛江玉,汪小康,生宸,张冠舜,任靖. 2024. 2021年7月20—22日豫北地区暴雨过程中尺度低涡和垂直运动发展的位涡动力学诊断. 气象学报,82(3):306-318. DOI: 10.11676/qxxb2024.20230072
Liu Ke, Mao Jiangyu, Wang Xiaokang, Sheng Chen, Zhang Guanshun, Ren Jing. 2024. Diagnosis of potential vorticity dynamics of mesoscale vortex and vertical motion development during the torrential rain event in northern Henan from 20 to 22 July 2021. Acta Meteorologica Sinica, 82(3):306-318. DOI: 10.11676/qxxb2024.20230072
Citation: Liu Ke, Mao Jiangyu, Wang Xiaokang, Sheng Chen, Zhang Guanshun, Ren Jing. 2024. Diagnosis of potential vorticity dynamics of mesoscale vortex and vertical motion development during the torrential rain event in northern Henan from 20 to 22 July 2021. Acta Meteorologica Sinica, 82(3):306-318. DOI: 10.11676/qxxb2024.20230072

2021年7月20—22日豫北地区暴雨过程中尺度低涡和垂直运动发展的位涡动力学诊断

Diagnosis of potential vorticity dynamics of mesoscale vortex and vertical motion development during the torrential rain event in northern Henan from 20 to 22 July 2021

  • 摘要: 2021年7月17—23日,河南省发生了一次大范围的强降水过程(简称河南“21.7”特大暴雨)。20—22日暴雨中心移至豫北地区,在太行山东侧新乡、鹤壁等地引发了洪涝灾害。基于自动雨量站观测和ERA5再分析数据,利用位涡倾向方程和垂直运动分解方法,对河南“21.7”特大暴雨事件中豫北地区暴雨过程中中尺度低涡及垂直运动发展的热动力学机制进行了诊断分析。结果表明:豫北地区强降水凝结潜热引起的大气非绝热加热,因其垂直分布在低空随高度上升而制造位涡,使得低层大气位涡增强,表明中尺度低涡发展;另外,加深的中尺度低涡又使得等熵面进一步下凹、倾斜坡度增大,从而增强大尺度东南暖湿气流向豫北地区的辐合与抬升,特别是沿等熵面上滑的上升运动分量和与凝结潜热有关的上升运动分量,导致降水进一步加强。由此,中尺度低涡、垂直运动和强降水发展之间形成一定的正反馈,在豫北造成持续性暴雨过程。

     

    Abstract: A persistent torrential rain process occurred in Henan province from 17 to 23 July 2021 (hereafter referred to as Henan "21.7" torrential rain). During 20—22 July, the center of the Henan "21.7" torrential rain moved to northern Henan, causing severe floods in Xinxiang, Hebi and other places on the east side of the Taihang mountains. Based on rainfall observations collected at automatic weather stations and ERA5 atmospheric reanalysis product, the thermodynamic mechanism for the mesoscale vortex and vertical motion development during the torrential rain event in northern Henan is diagnosed by using the Potential Vorticity (PV) tendency equation and the vertical motion decomposition method. The results show that the atmospheric diabatic heating caused by latent heat release during the precipitation process increased with height in the middle and lower troposphere, leading to the genesis of local PV and the development of mesoscale vortex. On the other hand, an intensified mesoscale vortex caused the isentropic surfaces to become more concave with more inclined surface, which enhanced the convergence and uplift of large-scale warm and moist southeasterlies in northern Henan. In particular, the isentropic-gliding ascending motion and the ascending motion induced by condensational latent heat release intensified, leading to further increases in precipitation. Therefore, the positive feedback loop formed between the mesoscale vortex and vertical motion and heavy precipitation development, resulting in the persistent torrential rain process in northern Henan.

     

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