丁乙,窦晶晶,王迎春,苗世光,樊利强. 2024. 华北平原及沿山和沿海五个城市夏季短历时降水过程的日变化分析. 气象学报,82(X):1-20. DOI: 10.116767/qxxb2024.20230147
引用本文: 丁乙,窦晶晶,王迎春,苗世光,樊利强. 2024. 华北平原及沿山和沿海五个城市夏季短历时降水过程的日变化分析. 气象学报,82(X):1-20. DOI: 10.116767/qxxb2024.20230147
Ding Yi, Dou Jingjing, Wang Yingchun, Miao Shiguang, Fan Liqiang. 2024. Diurnal variation analysis of short-duration rainfall events in the North China plain and five cities along mountains and along the coast during the summer season. Acta Meteorologica Sinica, 82(X):1-20. DOI: 10.116767/qxxb2024.20230147
Citation: Ding Yi, Dou Jingjing, Wang Yingchun, Miao Shiguang, Fan Liqiang. 2024. Diurnal variation analysis of short-duration rainfall events in the North China plain and five cities along mountains and along the coast during the summer season. Acta Meteorologica Sinica, 82(X):1-20. DOI: 10.116767/qxxb2024.20230147

华北平原及沿山和沿海五个城市夏季短历时降水过程的日变化分析

Diurnal variation analysis of short-duration rainfall events in the North China plain and five cities along mountains and along the coast during the summer season

  • 摘要: 利用华北平原294个国家级气象站1980—2022年夏季(6—8月)逐时降水资料,分析了华北平原夏季短历时降水过程的日变化时、空分布特征,结合地面气温和风的日变化,综合分析了4个沿山城市(北京、石家庄、济南、郑州)和1个沿海城市(天津),在城市发展前期(1980—1989年)和后期(2013—2022年)短历时降水过程日变化特征及差异。结果表明:华北平原短历时降水过程整体呈现傍晚单峰的日变化特征;平原站点的达峰时间自东南向西北推后。5个主要城市在城市发展后期,短历时降水过程的日振幅都出现不同程度的减小;沿山城市短历时降水过程日峰值出现时间提前了1—2 h,而沿海城市天津无明显峰值时间,且高值时段提前;沿山城市50 mm以上短历时降水过程概率均有所升高,其中北京和石家庄40 mm以上的降水过程概率分别升高了2倍和5倍,而沿海城市天津40 mm以上的降水过程概率下降了43%。华北平原短历时降水过程的日变化与局地地形的热、动力作用和地面盛行风有关。城市局地增温效应导致沿山、沿海城市与周围地形热力差异更加明显,增强了沿山城市的山风和沿海城市的海风;同时,城市增温导致城市午后地面风辐合增强。近地面层上述热力差异变化导致的风场变化可能是沿山城市短历时降水过程日峰值提前、沿海城市短历时降水过程集中时段变为白天的重要原因。

     

    Abstract: Based on hourly precipitation collected at 294 observation stations in the North China plain from 1980 to 2022 during the summer season (June to August), spatial and temporal distribution characteristics of diurnal variation of short-duration rainfall events in this region are explored. By combining diurnal variations of surface air temperature and prevailing surface winds, diurnal variations and differences in short-duration rainfall events in four cities along the mountains (Beijing, Shijiazhuang, Jinan, and Zhengzhou) and the coastal city Tianjin during the earlier (1980—1989) and later (2013—2022) stages of urban development are comprehensively analyzed. The diurnal variation of short-duration rainfall events in the North China plain generally exhibits an evening peak with the peak time shifting from southeast to northwest across the plain. In the later stage of urban development, the diurnal amplitude of short-duration rainfall events decreased to varying degrees in the five cities with the peak time of short-duration rainfall events advancing by 1—2 h in the cities along mountains, while no significant peak time was observed in the coastal city Tianjin. The probability of short-duration rainfall events exceeding 50 mm increased in all the four mountainous cities, and Beijing and Shijiazhuang respectively experienced two-fold and five-fold increases in the probability of heavy precipitation events exceeding 40 mm. However, the coastal city Tianjin witnessed a 43% decrease in the probability of heavy precipitation events exceeding 40 mm. The diurnal variation of short-duration rainfall events in the North China plain is related to thermodynamic effects of local terrain and prevailing surface winds. The urban heat island effect leads to a more pronounced thermal difference between cities along the mountains and the coast and their surrounding terrain, enhancing mountain winds in the cities along the mountains and sea breezes in coastal cities. At the same time, urban warming leads to strengthened surface wind convergence in the afternoon. The wind field changes caused by the evolution of thermal differences in the lower layer of the atmosphere may be an important reason for the earlier diurnal peak of short-duration precipitation processes in cities along the mountains and the concentration of short-duration precipitation processes during the daytime in the coastal city.

     

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