干旱气象 ›› 2022, Vol. 40 ›› Issue (6): 981-992.DOI: 10.11755/j.issn.1006-7639(2022)-06-0981

• 论文 • 上一篇    下一篇

有无台风影响下陕西西北涡暴雨特征对比分析

彭力1,2,4(), 赵强3,4, 乔丹杨4,5, 张雄1,2, 徐浩天1,2, 倪闻1,2   

  1. 1.陕西省铜川市气象局,陕西 铜川 727031
    2.陕西省铜川市中草药气象服务研究中心,陕西 铜川 727031
    3.陕西省气象台,陕西 西安 710014
    4.秦岭和黄土高原生态环境气象重点实验室,陕西 西安 710016
    5.陕西省咸阳市气象局,陕西 咸阳 712000
  • 收稿日期:2022-05-05 修回日期:2022-06-14 出版日期:2022-12-31 发布日期:2023-01-10
  • 作者简介:彭力(1990—),男,陕西商洛人,工程师,主要从事灾害性天气预报技术研究工作. E-mail:sxpeng3677@qq.com
  • 基金资助:
    陕西省重点研发计划(2021NY-183);秦岭和黄土高原生态环境气象重点实验室开放研究基金课题(2019M-1);秦岭和黄土高原生态环境气象重点实验室开放研究基金课题(2020Y-7)

Comparative analysis on characteristics of rainstorms caused by northwest vortex in Shaanxi with and without influence of typhoon

PENG Li1,2,4(), ZHAO Qiang3,4, QIAO Danyang4,5, ZHANG Xiong1,2, XU Haotian1,2, NI Wen1,2   

  1. 1. Tongchuan Meteorological Bureau of Shaanxi Province, Tongchuan 727031, Shaanxi, China
    2. Tongchuan Chinese Herbal Medicine Meteorological Service Research Center, Tongchuan 727031, Shaanxi, China
    3. Shaanxi Meteorological Observatory, Xi’an 710014, China
    4. Key Laboratory of Eco-Environment Meteorology for the Qinling Mountains and Loess Plateau, Xi’an 710016, China
    5. Xianyang Meteorological Bureau of Shaanxi Province, Xianyang 712000, Shaanxi, China
  • Received:2022-05-05 Revised:2022-06-14 Online:2022-12-31 Published:2023-01-10

摘要:

基于2010—2020年地面日降水量资料、高空观测资料以及ERA5(0.25°×0.25°)逐小时再分析资料,对影响陕西的西北涡暴雨天气过程进行统计,并对有无台风影响下西北涡暴雨天气特征进行对比分析。结果表明:陕西西北涡暴雨多发生在7—8月,陕北为暴雨多发区,西北涡暴雨夜雨特征明显;有台风影响时暴雨强度更强,落区比无台风影响时偏北2个纬度。造成陕西暴雨的西北涡位于西太平洋副热带高压脊线北侧7~8个纬度处,西北涡具有低层辐合、高层辐散的动力特征,地形强迫抬升加强了西北涡上升运动,低层水汽输送和水汽辐合为西北涡暴雨发生提供了有利条件。台风影响时,副热带高压偏西偏北,台风外围水汽、能量随着西南低空急流向西北涡输送,西北涡低层呈对流不稳定,高空槽前正涡度平流及高空急流右侧强辐散促使西北涡发展加强,低涡东侧和南侧强上升运动触发不稳定能量释放,在陕北形成强锋区,锋生进一步增强了低涡东侧与南侧垂直运动,造成该区域大暴雨;无台风影响时,副热带高压偏东偏南,西南风风速较小,水汽输送较弱,高原槽前西南风将孟加拉湾和南海水汽向陕西输送,西北涡低层大气层结稳定,低涡中心南部为强上升运动区,冷暖空气在陕西中南部交汇,产生分散的弱锋区,造成低涡中心南部暴雨天气。

关键词: 西北涡, 暴雨, 台风, 不稳定特征, 锋生

Abstract:

Based on daily precipitation data, upper-air observation data and ERA5 hourly reanalysis data with 0.25°×0.25° resolution from 2010 to 2020, the rainstorms caused by the northwest vortex in Shaanxi are counted, and the characteristics of rainstorms caused by the northwest vortex with and without influence of typhoon are comparatively analyzed. The results show that the rainstorms caused by the northwest vortex in Shaanxi mostly occurred in July and August, and it occurred more in northern Shaanxi. The night rain characteristics of the rainstorms are obvious. The rainstorm intensity was stronger under influence of typhoon, and the falling area was to the north of two latitudes than that without influence of typhoon. The northwest vortex, which caused rainstorms in Shaanxi, was located at about 7-8 latitudes to the north of the ridge line of the western Pacific subtropical high. The northwest vortex had the dynamic characteristics of convergence at low level and divergence at high level. The upward motion of the northwest vortex was strengthened by the topographic forcing uplift, and the low-level water vapor transport and convergence provided favorable conditions for the occurrence of rainstorms caused by the northwest vortex. Under the influence of typhoon, the subtropical high was westward and northward, the water vapor and energy in the periphery of the typhoon were transported to the northwest vortex with the southwesterly low-level jet, the atmosphere at lower layer of the northwest vortex was convective instability, and the positive vorticity advection in front of the high trough and strong divergence on the right side of the high-level jet promoted the development and enhancement of the vortex, the strong updrafts on the south and east sides of the vortex triggered the release of unstable energy and formed strong frontogenesis in northern Shaanxi, the frontogenesis further enhanced the vertical movement on the south and east sides of the vortex, which caused heavy rainstorms on the south and east sides of the vortex. When there was no influence of typhoon, the subtropical high was eastward and southward, the southwest wind speed was smaller and the water vapor transport was weaker, the southwest wind in front of the plateau trough transported water vapor from the Bay of Bengal and the South China Sea to Shaanxi, the atmosphere at lower layer of the northwest vortex was stable, the strong updraft was located in the south of the vortex, the cold and warm air converged in central and southern Shaanxi, which resulted in scattered weak frontogenesis and caused rainstorms in the south of the vortex center.

Key words: the northwest vortex, rainstorm, typhoon, instability characteristics, frontogenesis

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