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江苏梅雨期极端小时降水时空变化特征

The spatiotemporal variation characteristics of extreme hourly precipitation during the Meiyu period in Jiangsu Province

  • 摘要: 利用江苏省2001—2020年70个基本站的逐小时降水量观测资料,以第98百分位数为阈值,采用小提琴图的方法,分区域对梅雨期极端小时降水的时空变化特征进行分析,得出以下结论:(1) 全省极端小时降水量呈单峰正偏态分布,小时降水量集中在22.7 mm附近,最大值达184.7 mm,跨度极大。降水出现频次百分比在省内自北向南逐步递增,频次高的站点,年均梅雨期降水量也偏多。(2) 小时最大降水量在全省呈多个中心不均匀分布,当站点的降水量平均偏多、集中偏多或标准差较大时,往往极端性也更强。(3) 全省各站总(平均)极端小时降水量与降水频次在年际变化(日变化)中都呈明显正偏态分布,但在频次异常偏高的站点概率偏多、单站频次异常偏高的年份,站点降水量趋于极端的概率也更大、极端性也更强,这与日变化相反。极端小时降水偏多偏强的地区位于长江以南,且发生年份与El Niño的年份对应较好。(4) 淮北中午至凌晨时段易突发强极端小时降水;江淮之间在凌晨,长江以南则是在上午最易多发极端小时降水。江淮之间发生极端小时降水的高峰出现时段较长江以南偏早。

     

    Abstract: Based on hourly precipitation observation data from 70 basic stations in Jiangsu Province over the past 20 years (2001—2020), with the 98th percentile as threshold, the spatiotemporal variation characteristics of extreme hourly precipitation during the Meiyu period in different regions are analyzed using the violinplot method. The results are as follows. (1) The extreme hourly precipitation in the province shows a unimodal positively skewed distribution, with a concentration of 22.7 mm and a maximum value of 184.7 mm, which spans a wide range. The frequency percentage gradually increases from the north to the south. Stations with a higher frequency often have more annual average Meiyu precipitation. (2) The maximum hourly precipitation is unevenly distributed across multiple centers throughout the province. When the precipitation distribution of the station is with a high average or concentration, or a large standard deviation, the extreme is often stronger. (3) The total and average extreme hourly precipitation at each station in the province show a significant positive skewed distribution in both annual and daily variations, corresponding to the precipitation frequency. But in the years when the precipitation frequency probability of the stations is abnormally high and abnormally high frequency exists at a single station, the precipitation probability of the stations tending towards extreme is also higher and the extreme is stronger, which is exactly opposite to the daily variation. The areas with higher precipitation frequency and amount of extreme hourly precipitation are located south of the Yangtze River and the occurrence years are consistent well with the El Niño years. (4) The sudden intense extreme hourly precipitation usually occurs from noon to the next early morning in Huaibei region, high frequency usually occurs in the early morning in the area between the Yangtze River and the Huaihe River, and in the forenoon in the region south of the Yangtze River. The peak time of the extreme precipitation in the area between the Yangtze River and the Huaihe River appears earlier than that south of the Yangtze River.

     

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