Fine-scale spatio-temporal characteristics of short-term heavy precipitation and topographic influences in Zhengzhou

doi:10.11755/j.issn.1006-7639-2025-06-0920

Abstract

Abstract:

To gain an in-depth understanding of the fine-scale characteristics of short-term heavy precipitation under Zhengzhou’s complex terrain, based on hourly precipitation data from national and regional stations from 2013 to 2022, conventional observation data, and high-precision geographic information data, this study systematically analyzes the multi-temporal scale variations and spatial distribution patterns of short-term heavy precipitation in Zhengzhou and quantitatively explores the relationships between precipitation intensity, frequency and topographic factors. Combining the case study of the extreme torrential rain event occurring in July 2021 (“21·7”) in Zhengzhou, the study reveals the thermodynamic mechanisms through which terrain triggers and enhances short-term heavy precipitation. The results indicate that the station-based frequency of short-term heavy precipitation in Zhengzhou shows a fluctuating increasing trend, July and August are the peak occurrence periods. The active period is between 14:00 and 20:00 (Beijing Time, the same as below), peaking from 18:00 to 20:00. The probability of daytime occurrence in mountainous areas is significantly higher than in plains. The short-term heavy precipitation events with rainfall intensity greater than or equal to 20 mm·h?¹ occur mostly in mountainous areas, whereas extreme events with rainfall intensity greater than or equal to 50 mm·h?¹ are more likely in the Zhengzhou main urban area and Xinmi City, reflecting a spatial distribution pattern where mountainous areas experience higher frequency but relatively lower intensity, while urban areas exhibit stronger extremity. Circulation classification shows that under weak synoptic-scale forcing backgrounds, the number of station occurring short-term heavy precipitation in mountainous areas is significantly greater than that in plain areas. Terrain’s influence on rainfall intensity distribution of short-term heavy precipitation is not significant, but it has a clear impact on its frequency. During the “21·7” torrential rain process, the triggering effect of the terrain convergence line and the mechanism of convective enhancement caused by the uplift on the windward slope and the thermal difference of the underlying surface are particularly prominent.

Key words: short-term heavy precipitation, spatio-temporal distribution, topographic influence, Zhengzhou

摘要：

为深入认识郑州复杂地形下短时强降水的精细特征，基于2013—2022年国家站和区域站逐小时降水数据，常规观测资料以及高精度地理信息数据，分析郑州短时强降水的多时间尺度和空间变化规律，探讨降水强度、发生频次与地形因子的关系；并结合郑州2021年7月（“21·7”）的极端特大暴雨事件，揭示地形对短时强降水触发和增强的热动力机制。结果表明，郑州短时强降水站次呈波动增加趋势，7—8月为高发期，14：00—20：00（北京时，下同）为活跃时段，峰值出现在18：00—20：00，白天山区发生概率显著高于平原；≥20 mm·h?¹的短时强降水主要出现在山区，而≥50 mm·h?¹的极端强降水更易发生在郑州主城区及新密市一带，反映出山区频次高但强度相对偏弱、城区极端性更强的空间分布特征；环流分型显示，弱天气尺度强迫背景下，山区短时强降水站次明显多于平原；地形对短时强降水强度分布影响不显著，但对发生站次有明确影响。“21·7”暴雨过程中，地形辐合线的触发作用以及迎风坡抬升与下垫面热力差异共同导致的对流增强机制较为突出。

关键词: 短时强降水, 时空分布, 地形影响, 郑州

CLC Number:

P458

CUI Huihui, LI Rong, SUN Cunyong. Fine-scale spatio-temporal characteristics of short-term heavy precipitation and topographic influences in Zhengzhou[J]. Journal of Arid Meteorology, 2025, 43(6): 920-930.

崔慧慧, 李荣, 孙存永. 郑州短时强降水精细时空分布特征及地形影响[J]. 干旱气象, 2025, 43(6): 920-930.

Figures/Tables 13

Fig.1 Administrative area division， meteorological station distribution and terrain height （Unit： m） of Zhengzhou

Fig.2 The yearly (a) and monthly (May to August) (b) variations of the number of stations occurring short-term heavy precipitation from 2013 to 2022 in Zhengzhou

Tab.1 Maximums of short-term heavy precipitation intensity from May to August during the period of 2013-2022 in Zhengzhou

	2013	2014	2015	2016	2017	2018	2019	2020	2021	2022
5月	52.3	72.6	29.3	—	77.8	68.6	27.7	—	39.2	—
6月	61.6	92.5	—	85.2	45.7	38.9	37.3	48.4	39.9	61.9
7月	121.8^*	60.9	41.8	79.2^*	58.3	84.7^*	64.9	56.1	201.9^*	103.7^*
8月	97.6	92.5^*	58.1^*	45.9	77.9^*	78.9	88.2^*	92.4^*	71.4	49.6

Fig.3 Hourly variation of the number of stations occurring short-term heavy precipitation and maximum rainfall intensity from 2013 to 2022 in Zhengzhou

Fig.4 Spatial distributions of station numbers (a, b) and precipitation intensity (c, d) for short-term heavy precipitation events with hourly rainfall equal to or greater than 20 mm (a, c) and equal to or greater than 50 mm (b, d) from 2013 to 2022 in Zhengzhou

Fig.5 The box plots of short-term heavy precipitation intensity (a), station numbers (b) and altitude in Zhengzhou (The R represents precipitation intensity, F represents the number of stations occurring short-term strong precipitation)

Fig.6 Meteorological conceptual model of short-term heavy precipitation in Zhengzhou (a) internal type of subtropical high pressure, (b) high-altitude northwest airflow type, (c) typhoon low pressure type, (d) high altitude trough type

Tab. 2 Influence coefficients and significance values for short-term heavy precipitation cases passing the significance test （α=0. 05）

Fig.7 The 925 hPa horizontal wind field (arrow vectors, Unit: m·s-1) and water vapor flux (the color shaded, Unit: g·cm-1·hPa-1·s-1) at 08:00 July 19 (a) and 08:00 July 20 (b), 2021 (The ● represents the location of Zhengzhou)

Fig.8 Variation of hourly precipitation at Gongyi Wenhuazhan Station from 20：00 July 18 to 08：00 July 21， 2021

Fig.9 Surface wind field at 08:00 (a) and composite radar reflectivity at 09:00 (the color shaded, Unit: dBZ) (b) over Zhengzhou on 19 July 2021 (The red rectangle in figure 9 (a) denotes a mesoscale convergence zone, and the red rectangle in figure 9 (b) indicates an area with repeatedly triggered convection over the mountainous region)

Fig.10 Radar composite reflectivity （Unit： dBZ） in Zhengzhou at 08：30 （a）， 09：12 （b）， and 10：00 （c） on 19 July 2021 （The black rectangle indicates the area of the windward slope in the eastern section of the Songshan Mountain）

Fig.11 Distribution of surface temperature (isolines, Unit: °C) (a) and dew point (isolines, Unit: °C) (b)overlaid on topography (the color shaded, Unit: m) in Zhengzhou at 08:00 on 19 July 2021

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