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[J]. 气象学报, (0):-, doi:[doi]
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
投稿时间:2023-05-10  修订日期:2024-01-09
DOI:
中文关键词:  河南暴雨,位涡,垂直运动,非绝热加热,中尺度低涡
英文关键词:Henan heavy rain, Potential vorticity, Vertical motions, Diabatic heating, Mesoscale vortex
基金项目:国家自然科学基金
作者单位邮编
刘柯 中国气象局武汉暴雨研究所 430200
毛江玉* 中国科学院大气物理研究所 100029
汪小康 中国气象局武汉暴雨研究所 430200
生宸 中国科学院大气物理研究所 100029
张冠舜 中国气象局广州热带海洋气象研究所 510641
任靖 中国气象局武汉暴雨研究所 430205
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中文摘要:
      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。[资料和方法]基于自动雨量站数据和ERA5再分析数据,利用位涡倾向方程和新型垂直运动分解方法,[目的]对河南“21·7”特大暴雨事件中豫北地区暴雨过程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] [结论]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增加而制造位涡,使得低层大气位涡增强,表明中尺度低涡发展;另一方面,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。
英文摘要:
      A persistently torrential rain process occurred in Henan Province from 17 to 23 July 2021(referred to as Henan "21·7" torrential rain). During July 20–22, 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 Taihang Mountain. Based on automatic station-observed rainfall data and ERA5 atmospheric reanalysis data, 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 precipitation-released condensation latent heating gave rise to the local PV, which was due to vertical structure of the diabatic heating increasing with height in middle and lower troposphere, indicating the development of mesoscale vortex. On the other hand, such an intensified mesoscale vortex caused the isentropic surfaces to become more concave and sloping, which enhanced the convergence and uplift of large-scale warm and humid southeasterlies toward northern Henan, especially the isentropic-gliding ascending motion and the condensation latent heating-related ascending motion, leading to further increasing of precipitation. Therefore, a positive feedback was formed between the mesoscale low vortex, vertical motion and heavy precipitation development, resulting a persistent torrential rain process in northern Henan.
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