Analysis of the three-dimension structure and triggering mechanism of a severe downslope windstorm case in north edge of Tianshan canyon

doi:10.11755/j.issn.1006-7639-2026-02-0241

Abstract

Abstract:

An extreme gale event occurred in Urumqi from April 29 to May 3, 2022. The duration of gale-force winds in the southern suburbs lasted for 65 h, representing the longest duration in nearly a decade. Based on meteorological observation data, reanalysis data, and high-resolution numerical simulations, the three-dimensional structure and triggering mechanism of this gale event were systematically analyzed. The results show that the eastward movement of the Mongolian High, together with the pressure decrease ahead of the frontal system in northern Xinjiang, established and maintained a pressure pattern characterized by higher pressure to the south and lower pressure to the north across the Tianshan Mountains. The pressure difference extended from the surface to the upper levels, with a top height reaching about 4 000 m, providing a stable dynamical condition for the continuous acceleration of airflow within the canyon. Driven by a strong pressure gradient force, the airflow entered the Tianshan canyon from the southern end and was continuously accelerated under the effects of topographic forcing and funneling, eventually developing into a typical topographic low-level jet. As the airflow entered the canyon, gravity waves were triggered by topographic lifting, and the low-level jet subsided along the leeward slope with the propagation of gravity waves. The strong wind zone gradually expanded toward the near-surface layer, thereby triggering a downslope windstorm. In addition, during the gale period, persistent stable stratification existed above the leeward slope and was accompanied by evident subsidence, which effectively suppressed vertical mixing and enhanced downward momentum transport, playing an important role in the development and maintenance of the downslope windstorm.

Key words: downslope windstorm, effect of funneling, topographic low-level jet, gravity wave, turbulent kinetic energy

摘要：

2022年4月29日至5月3日，乌鲁木齐出现一次极端东南大风过程，其中南郊8级以上阵风持续65 h，为近10 a持续时间最长的一次大风过程。基于站点观测资料和再分析资料，并结合高分辨率数值模拟，对此次大风过程的三维结构及触发机理进行系统分析。结果表明：蒙古高压东移及北疆锋前减压共同作用，形成并维持天山两侧南高北低的气压分布格局。气压差自地面向高空延伸，顶高可达4 000 m，为峡谷内气流持续加速提供稳定动力条件。在较强气压梯度力驱动下，气流自峡谷南端进入天山峡谷，在地形强迫及狭管效应作用下持续加速，发展为典型的地形性低空急流。气流在进入峡谷过程中受地形抬升激发重力波，低空急流沿重力波背风坡发生下沉，强风区逐渐向近地面扩展，从而触发地面下坡风暴。此外，大风期间背风坡上空持续存在较强稳定层结结构，并伴随明显下沉运动，有效抑制垂直混合，增强动量向下输送，对下坡风暴的发展和维持具有重要作用。

关键词: 下坡风暴, 狭管效应, 地形性低空急流, 重力波, 湍流动能

CLC Number:

P445
P458

TANG Hao, ZHOU Yaman, AN Dawei, WANG Minzhong. Analysis of the three-dimension structure and triggering mechanism of a severe downslope windstorm case in north edge of Tianshan canyon[J]. Journal of Arid Meteorology, 2026, 44(2): 241-253.

汤浩, 周雅蔓, 安大维, 王敏仲. 天山峡谷北缘一次极端下坡风暴三维结构及触发机理分析[J]. 干旱气象, 2026, 44(2): 241-253.

Figures/Tables 10

Fig.1 Topography （the color shaded） and triply nested model domains （a） and meteorological stations （black dots） and subregions within the D03 domain （b）（The red rectangle indicates the study area， the same as below； points A， B， and D denote reference locations along the airflow path， point C represents the Hongyanchi Station， the same as below； and the blue line indicates the cross-sectional location of the airflow over the mountain）

Tab.1 Parameterized scheme setting of WRF model

物理参数化方案	设置
微物理（mp_phyisics）	WSM3（Hong et al.，2004）
积云（cu_physics）	Kain-Fritsch（D02、D03关闭）（Kain，2004）
长波辐射（ra_lw_physics）	RRTM（Mlawer et al.，1997）
短波辐射（ra_sw_physics）	Dudhia（Dudhia，1993）
陆面（sf_surface_physics）	Noah land Surface Model（Noilhan and Planton，1989）
近地层（sf_sfclay_physics）	MM5 Similarity（Skamarock et al.，2005）
边界层（PBL）	Shin和Hong（开启湍流动能输出）（Shin and Hong，2015）

Fig.2 Observed hourly wind speed and direction at representative stations during the extreme gale event in Urumqi from 29 April to 3 May 2022

Fig.3 The geopotential height （the contour lines， Unit： dagpm） and wind field （arrow vectors， Unit： m·s-1） at 500 hPa （a， c， e） and sea level pressure field （the contour lines， Unit： hPa） and 850 hPa wind field （arrow vectors， Unit： m·s-1）（b， d， f） at 08：00 on April 29 （a， b）， 14：00 on May 1 （c， d）， 20：00 on May 3 （e， f） 2022 （The letter G and D represent the high-pressure and low-pressure center， respectively）

Fig.4 The daily variation of mean sea level pressure （a， c） in Urumqi and Turpan and its pressure difference （Turpan minus Urumqi， the same as below； b， d） during April-May of 1991-2020 （a， b） and from 26 April to 6 May 2022 （c， d）

Fig.5 Observed and simulated wind speed （solid lines） and wind direction （arrow vectors） at Hongyanchi （a） and Urumqi （b）， and sea level pressure in Urumqi and Turpan （c） and pressure difference （d） from 29 April to 3 May 2022 （Vertical lines 2， 4， 6， and 8 denote the peak times of simulated wind speed at Hongyanchi； lines 3， 5， and 7 denote the trough times； lines 1 and 9 denote the onset and termination times of the gale event）

Fig.6 Wind speed （the color shaded） and wind direction （arrow vectors） at 3 000 m （a， b， c， d）， 2 000 m （e， f， g， h）， 1 500 m （i， j， k， l）， and 10 m above ground （m， n， o， p） at 22：00 on 29 April （a， e， i， m）， 21：00 on 30 April （b， f， j， n）， 11：00 on 1 May （c， g， k， o）， and 20：00 on 3 May （d， h， l， p） 2022 （Unit： m·s-1）（The gray shading indicates terrain， the same as below）

Fig.7 Hourly variation of simulated wind speed at Hongyanchi Station (a), and time-height cross sections of the pressure difference between Turpan and Urumqi (b, Unit: hPa), squared buoyancy frequency on the windward (c) and leeward (d) slopes (the color shaded, Unit: 10-4 s-2) from 29 April to 3 May 2022 （The blue line denotes the boundary layer height， Unit： km）

Fig.8 The variations of horizontal wind speed （the color shaded， Unit: m·s-1）， potential temperature （contour lines， Unit： K）， and the combined horizontal wind speed and vertical motion （arrow vectors， Unit： m·s-1） with height along the airflow passing through the Tianshan canyon together with the pressure difference profile between Turpan and Urumqi at 22：00 on 29 April （a）， 11：00 on 30 April （b）， 11：00 on 1 May （c）， 11：00 on 2 May （d）， 13：00 on 3 May （e）， and 20：00 on 3 May （f） 2022 （Black dots indicate the height of the maximum wind speed layer exceeding 12 m·s-1 from the surface to 5 km， the same as below）

Fig.9 The variations of TKE (the contour lines, Unit: m2·s2) and vertical motion (the color shaded, Unit: m·s-1) with height along the airflow passing through the Tianshan canyon at 22:00 on 29 April (a), 11:00 on 30 April (b), 11:00 on 1 May (c), 11:00 on 2 May (d), 13:00 on 3 May (e), and 20:00 on 3 May (f) 2022

References 36

[1]	黄海波, 陈阳权, 王清平, 2014. 乌鲁木齐机场东南大风数值预报及地形敏感性试验[J]. 气象科技, 42(6):1064-1 068.
[2]	靳双龙, 刘晓琳, 王勃, 等, 2024. 地面气压在纵向峡谷区大风预报中的应用探讨[J]. 干旱气象, 42(5):804-812. DOI
[3]	李国平, 许一洲, 张晓玉, 等, 2025. 四川盆地一次暴雨过程的重力波与西南涡关系研究[J]. 高原山地气象研究, 45(1):9-19.
[4]	李艺苑, 王东海, 王斌, 2009. 中小尺度过山气流的动力问题研究[J]. 自然科学进展, 19(3):310-324.
[5]	卢冰, 史永强, 王光辉, 等, 2014. 新疆克拉玛依强下坡风暴的机理研究[J]. 气象学报, 72(6):1218-1 230.
[6]	孟齐辉, 吕斌, 刁平, 1996. 乌鲁木齐地区东南大风与气压场演变的关系[J]. 新疆气象, 19(1):5-9.
[7]	肉孜·阿基, 李如琦, 阿不力米提江·阿布力克木, 等 2015. 乌鲁木齐一次强东南大风天气成因分析[J]. 干旱气象, 33(3):474-480. DOI
[8]	桑建国, 1989. 下坡运动的分析解[J]. 气象学报, 47(2):191-198.
[9]	汤浩, 陆汉城, 储长江, 等, 2020. 天山峡谷穿谷急流触发强下坡风暴的中尺度特征分析[J]. 气象, 46(11):1450-1 460.
[10]	王蓉, 吴稀稀, 岳平, 等, 2023. 青藏高原东北边坡复杂地形重力波的数值模拟[J]. 大气科学学报, 46(5):738-752.
[11]	肖庆农, 伍荣生, 1995. 地形对于气流运动影响的数值研究[J]. 气象学报, 53(1):38-49.
[12]	新疆维吾尔自治区气象局, 2023. 2022年新疆十大天气气候事件[EB/OL]. (2023-01-18)[2025-08-04]. http://xj.cma.gov.cn/xwzx/qxyw/202301/t20230118_5268969.html.
[13]	杨大升, 刘余滨, 刘式适, 1980. 动力气象学[M]. 北京: 气象出版社.
[14]	杨洪儒, 王楠, 2014. 地窝堡机场东南大风特征及其大气结构[J]. 干旱气象, 32(3):393-398. DOI
[15]	叶笃正, 1956. 小地形对气流的影响[J]. 气象学报, 27(3):243-262.
[16]	殷青青, 任璐, 田文寿, 等, 2022. 华北地区一次对流激发重力波的卫星观测和数值模拟研究[J]. 干旱气象, 40(3):444-456. DOI
[17]	于晓晶, 张丽霞, 于志翔, 等, 2025. 2025年1月美国洛杉矶破纪录山火事件的干旱气象条件归因[J]. 干旱气象, 43(5):667-677. DOI
[18]	张家宝, 苏起元, 孙沈清, 等, 1986. 新疆短期天气预报指导手册[M]. 乌鲁木齐: 新疆人民出版社:330-336.
[19]	赵斯楠, 赵海燕, 代潭龙, 等, 2025. 高温和干旱对美国加利福尼亚州山火的影响[J]. 干旱气象, 43(5):689-700. DOI
[20]	BRINKMANN W A R, 1974. Strong downslope winds at boulder, Colorado[J]. Monthly Weather Review, 102(8): 592-602. DOI URL
[21]	CLARK T L, PELTIER W R, 1984. Critical level reflection and the resonant growth of nonlinear mountain waves[J]. Journal of the Atmospheric Sciences, 41(21): 3 122-3 134. DOI URL
[22]	DUDHIA J, 1993. A nonhydrostatic version of the Penn state-NCAR mesoscale model: Validation tests and simulation of an Atlantic cyclone and cold front[J]. Monthly Weather Review, 121(5): 1 493-1 513.
[23]	DURRAN D R, 1986. Another look at downslope windstorms. Part I: The development of analogs to supercritical flow in an infinitely deep, continuously stratified fluid[J]. Journal of the Atmospheric Sciences, 43(21): 2 527-2 543.
[24]	HONG S Y, DUDHIA J, CHEN S H, 2004. A revised approach to ice microphysical processes for the bulk parameterization of clouds and precipitation[J]. Monthly Weather Review, 132(1): 103-120. DOI URL
[25]	KAIN J S, 2004. The Kain-Fritsch convective parameterization: An update[J]. Journal of Applied Meteorology, 43(1): 170-181. DOI URL
[26]	KLEMP J B, LILLY D K, 1978. Numerical simulation of hydrostatic mountain waves[J]. Journal of the Atmospheric Sciences, 35(1): 78-107. DOI URL
[27]	LILLY D K, 1978. A severe downslope windstorm and aircraft turbulence event induced by a mountain wave[J]. Journal of the Atmospheric Sciences, 35(1): 59-77. DOI URL
[28]	MLAWER E J, TAUBMAN S J, BROWN P D, et al, 1997. Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave[J]. Journal of Geophysical Research: Atmospheres, 102(D14): 16 663-16 682.
[29]	NOILHAN J, PLANTON S, 1989. A simple parameterization of land surface processes for meteorological models[J]. Monthly Weather Review, 117(3): 536-549. DOI URL
[30]	OKAMOTO K, SATO K, AKIYOSHI H, 2011. A study on the formation and trend of the Brewer-Dobson circulation[J]. Journal of Geophysical Research, 116(D10): D10117. DOI:10.1029/2010jd014953.
[31]	SHESTAKOVA A A, TOROPOV P A, MATVEEVA T A, 2020. Climatology of extreme downslope windstorms in the Russian Arctic[J]. Weather and Climate Extremes, 28: 100256. DOI:10.1016/j.wace.2020.100256.
[32]	SHIN H H, HONG S Y, 2015. Representation of the subgrid-scale turbulent transport in convective boundary layers at gray-zone resolutions[J]. Monthly Weather Review, 143(1): 250-271. DOI URL
[33]	SKAMAROCK W C, KLEMP J B, DUDHIA J, et al, 2005. A description of the advanced research WRF version 2[M]. Boulder, Colorado: NCAR.
[34]	SMITH C M, SKYLLINGSTAD E D, 2011. Effects of inversion height and surface heat flux on downslope windstorms[J]. Monthly Weather Review, 139(12): 3 750-3 764.
[35]	VOSPER S B, 2004. Inversion effects on mountain lee waves[J]. Quarterly Journal of the Royal Meteorological Society, 130(600): 1 723-1 748.
[36]	ZHANG G X, ZHANG D L, SUN S F, 2018. On the orographically generated low-level easterly jet and severe downslope storms of March 2006 over the Tacheng Basin of northwest China[J]. Monthly Weather Review, 146(6): 1 667-1 683.