青藏高原东北侧一次锋后极端暴雨成因分析

展开
  • 1. 兰州中心气象台,甘肃 兰州 730020
    2. 中国气象局兰州干旱气象研究所,甘肃省干旱气候变化与减灾重点实验室/
    中国气象局干旱气候变化与减灾重点开放实验室,甘肃 兰州 730020
    3. 高原与盆地暴雨旱涝灾害四川省重点实验室,四川 成都 610072

网络出版日期: 2025-02-24

基金资助

甘肃省自然科学基金项目(24JRRA117821JR7RA697);甘肃省气象局气象科研重点项目(Zd20284-B-2);干旱气象科学研究基金项目(IAM202308);国家自然科学基金重点项目(U2142208);甘肃省青年科技基金(23JRRA133022JR5RA755);高原与盆地暴雨早涝灾害四川省重点实验室开放研究基金项目(SZKT202103

Cause Analysis of a Post-frontal Extreme Rainstorm on the Northeast Side of Qinghai-Xizang Plateau

Expand
  • 1. Lanzhou Central Meteorological ObservatoryLanzhou 730020GansuChina
    2. Northwestern Regional Center of Numerical Weather Prediction/Key Laboratory of Arid Climate Change and Disaster Reduction of China Meteorological Administration and Gansu ProvinceInstitute of Arid Meteorology of China Meteorological AdministrationLanzhou 730020GansuChina
    3. Heavy Rain and Drought - Flood Disasters in Plateau and Basin Key Laboratory of Sichuan ProvinceChengdu 610072SichuanChina

Online published: 2025-02-24

摘要

2022813-14日青藏高原东北侧甘肃榆中地区出现极端暴雨事件,日降水量达130. 6 mm,最大小时降水量36. 6 mm,突破了该地区历史极值,造成了严重的社会影响和经济损失。本文利用地面分钟级气象观测以及高空观测、兰州多普勒天气雷达及欧洲中期天气预报中心第5代全球大气再分析产品(ECMWF Reanalysis v5ERA5)等资料,通过分析此次极端暴雨中两个强降水阶段的观测特征、环境条件、地形影响和不稳定机制等。结果表明:(1)暴雨由西风带短波槽带来的弱冷空气和副热带高压外围的暖湿空气在陇中地区交汇引起,700 hPa 切变线提供了动力抬升条件,地面冷锋提供了触发条件。(2)暴雨过程雷达反射率因子表现为持久的强回波并伴有后向传播特征,存在低空急流和明显的辐合,在第二阶段冷锋后部回波顶高和第一阶段相当,但是范围更大,且结构更为紧密,对流云发展更加旺盛。(3)此次暴雨水汽条件充沛,第一阶段低层强烈辐合、上升运动以及较高的对流有效位能,存在显著的对流不稳定,第二阶段的上升运动有所减弱,对流有效位能为 0,动力及对流不稳定条件弱。(4)冷锋斜压锋生触发不稳定能量的释放是第一阶段降水的主要触发机制。冷锋过境后,第二阶段降水由地形、锋生次级环流及不稳定等共同作用形成。由于夏季冷锋后强降水在青藏高原东北侧地区并不常见,在业务中容易形成该类暴雨的漏报。因此,需要加强对此类过程的监测和预警。

本文引用格式

伏 晶, 段海霞, 傅 朝, 李晨蕊, 沙宏娥, 宋兴宇 . 青藏高原东北侧一次锋后极端暴雨成因分析[J]. 高原气象, 0 : 1 . DOI: 10. 7522/j. issn. 1000-0534. 2024. 00117

Abstract

On August 13-142022an extreme rainstorm event occurred in Yuzhong region of Gansu Provincenortheast of the Qinghai-Xizang Plateau. Accumulated daily precipitation reached 130. 6 mm and the maximum hourly precipitation was 36. 6 mmbreaking the heaviest daily precipitation records of the region and causing serious social impact and economic losses. Based on the data of surface minute observation and high altitude observationLanzhou Doppler radar and ECMWF Reanalysis v5ERA5),by analyzing the observation characteristicsenvironmental conditionstopographic effects and instability mechanism of the two heavy precipitation stages in this extreme rainstormthe results show that:(1The rainstorm was caused by the convergence of weak cold air brought by the shortwave trough in the westerlies and warm and humid air outside the subtropical high in the Longzhong area. The 700 hPa shear line provided the dynamic lifting conditionsand the surface cold front provided the triggering conditions.2The radar reflectance factor in the rainstorm process was characterized by persistent strong echoes accompanied by "backward propagation"low-level jets and obvious convergence. In the second stagethe echo top height behind the cold front was similar to that in the first stagebut the scope was larger and the structure was more compactand the convective cloud development was more vigorous. 3The water vapor conditions of the rainstorm were abundant. In the first stagethere was significant convective instability due to strong convergence and upward movement at the lower level and high convective effective potential energy. In the second stagethe upward movement was weakenedthe convective effective potential energy was 0and the dynamic and convective instability conditions were weak.4The release of unstable energy triggered by cold front baroclinic frontogenesis was the main triggering mechanism of precipitation in the first stage. After the transit of the cold frontthe precipitation in the second stage was formed by the combination of terrainfrontogenic secondary circulation and instability. Since the heavy precipitation after the summer cold front was not common in the northeast part of the Qinghai-Xizang Plateauforecasters tended to ignore such kind of rainstorms. Thereforewe need to strengthen monitoring and early warning of such rainstorm events.

 

文章导航

/