渠江流域短时强降水气候特征分析

Climatic Characteristics of Short-term Heavy Rainfall in Qujiang River Basin

  • 摘要: 利用2009—2018年达州、巴中、广安14个国家基本观测站和117个区域自动站逐时降水资料,分析渠江流域短时强降水发生频次、小时雨强极值的多尺度时空变化特征。结果表明:(1)除个别年份外,2009—2018年渠江流域≥50 mm/h短时强降水每年发生频次均在10次以上,特别是2014年以后呈增加趋势。(2)渠江流域多年平均的短时强降水发生频次月际变化呈单峰型分布,峰值均出现在7月。(3)渠江流域短时强降水多发生在02—08时,夜雨特征非常显著,白天随着气温升高在16时左右有一个次高峰。(4)春季渠江流域短时强降水主要出现在早晨,白天不易出现短时强降水;夏季峰值在06时前后,白天午后也有一个次峰值,谷值在19—23时;秋季峰值在早晨,谷值不明显。(5)渠江流域短时强降水平均强度介于28~29 mm/h之间,2014年以后40 mm/h以上的短时强降水呈增加趋势。(6)年内最大小时雨强主要出现在5—9月,7月最多,6月次之。(7)渠江流域下游地区短时强降水发生频次较中上游偏少。

     

    Abstract: Based on the hourly precipitation data of 14 national basic observation stations and 117 regional automatic stations in Dazhou, Bazhong, and Guang'an from 2009 to 2018, this paper analyzes the multi-scale spatial and temporal variation characteristics of short-term heavy precipitation frequency and hourly rainfall intensity extreme value in Qujiang River Basin. The results show that: (1) The frequency of short-term heavy precipitation in the Qujiang River Basin with a precipitation of ≥50 mm/h is more than 10 times per year, and there is an increasing trend after 2014. (2) The monthly average number of short-term heavy precipitation events follows a unimodal distribution, with the peak occurring in July. (3) Short-term heavy precipitation mostly occurs from 02:00 to 08:00 with a significant characteristic of night rain. During the day, there is a secondary peak around 16:00 with the increase of temperature in the daytime. (4) Short-term heavy precipitation mainly occurs in the morning in spring, and it is not easy to occur during the day. The peak value in summer is around 06:00, and there is also a secondary peak in the afternoon during the day, with a valley value between 19:00 and 23:00. The peak value in autumn is in the morning, and the valley value is not obvious. (5) The average intensity of short-term heavy precipitation is between 28 and 29 mm/h, and there has been an increasing trend of short-term heavy precipitation above 40 mm since 2014. (6) The annual maximum hourly rainfall intensity mainly occurs from May to September, with the highest intensity in July and the second highest intensity in June. (7) The frequency of short-term heavy precipitation in the lower reaches of the Basin is less than that in the middle and upper reaches.

     

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