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近20 a沁河流域暖季极端小时降水时空特征分析

Analysis of temporal and spatial characteristics of extreme hourly precipitation in the warm season in the Qinhe River Basin in the recent 20 years

  • 摘要: 基于2004—2023年暖季(5—9月)黄河中游沁河流域10个国家气象站逐小时降水观测资料,分析了该流域暖季极端小时降水的时空变化特征,并对比了2018—2023年该流域96个省级气象站资料分析结论,以验证短时间序列、低空间密度国家气象站数据的代表性。结果表明:(1) 国家站极端小时降水阈值、强度、年均频次及对暖季降水的贡献率均呈现中上游小于下游地区的空间分布特征,但降水强度、频次和贡献率的变化趋势并不显著。(2) 国家站极端小时降水月变化呈单峰型,7月极端小时降水强度最大、频次最高、贡献率最大。日变化分布呈双峰型,09时和13时发生频次最高,01时发生频次最低,白天与夜间降雨强度相差不大。50 mm·h−1以上的极端小时强降水出现在6—8月,7月出现频次最高,05时和07时出现次数最多。(3) 省级气象站极端小时降水阈值、强度和贡献率的空间分布和降水日变化特征与国家气象站特征一致,只是50 mm·h−1以上的极端小时强降水峰值出现时段有所差异,因此基于长时间序列低空间密度的国家气象站资料分析结果可信,具有代表性,可为沁河流域极端小时降水预报预警、流域气候分析及气候可行性论证等工作提供参考依据。

     

    Abstract: Qinhe River basin in the middle reaches of the Yellow River during the warm season (May-September) from 2004 to 2023, the spatiotemporal variation characteristics of extreme hourly precipitation in the Qinhe River basin during the warm season were analyzed. To verify the representativeness of the national meteorological station data, the analyzed spatiotemporal variation characteristics were compared with the results from data analysis utilizing information from 96 Provincial meteorological stations from 2018 to 2023. The results are as follows. (1) The spatial distribution characteristics of extreme hourly precipitation threshold, intensity, annual average frequency, and contribution to precipitation in the warm season are lower in the middle and upper reaches than those in the lower reaches. However, the trends in changes in precipitation intensity, frequency, and contribution rates are not significant. (2) The monthly variation presents an unimodal pattern, with the highest frequency and intensity of extreme hourly precipitation occurring in July. The diurnal variation distribution presents a bimodal pattern, with the highest frequency occurring at 09:00 BT and 13:00 BT, and the lowest frequency occurring at 01:00 BT. There is little difference in the intensity of daytime and nighttime rainfall. Extreme hourly heavy precipitation exceeding 50 mm·h−1 usually occurs between June and August, with the highest frequency of occurrence in July, and the most frequent occurrences at 05:00 BT and 07:00 BT. (3) The spatial distribution of extreme hourly precipitation thresholds, intensity, and contribution rates, as well as the diurnal variation characteristics of precipitation, based on the analysis of data from Provincial meteorological stations in the Qinhe River basin, are consistent with those derived from national meteorological station data. However, for extreme hourly heavy precipitation peaks above 50 mm·h-1, there are differences in the periods when the peak precipitation occurs between the two datasets. Nevertheless, the monthly and diurnal trends exhibited by both datasets remain consistent. Therefore, the analysis results based on the long-term series of national station data are reliable and representative, providing a reference for extreme hourly precipitation forecasting and warning, basin climate analysis, climate feasibility studies, and other related work in the Qinhe River basin.

     

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