甘肃省暖季小时降水变化特征

Spatial and Temporal Distribution of Hourly Precipitation in Warm Season in Gansu Province

利用2013—2019年暖季(4—9月)小时降水资料,分析了甘肃省强降水极值及频率的时空分布特征。结果表明:(1)甘肃省小时强降水频次呈东高西低分布,在陇南地区东南部及陇东地区北部有2个高中心,达到29次。(2)小时强降水极值在陇中及其以南地区高,向西北递减,陇南地区降水极值最高,超过40 mm/h。(3)小时强降水频次主要出现在7—8月,同期的雨强也最大;小时强降水频次和小时雨强均在17—24时最强,峰值在21时。(4)不同区域的降水日内变化存在明显差异,河西地区小时降水频次的峰值出现在18时,陇中和陇南地区均出现在21时,陇东地区和甘南高原分别出现在22和19时。

Based on hourly precipitation data in the warm season(April-September) from 2013 to 2019,the spatial and temporal distribution characteristics of extreme value and frequency of heavy precipitation in Gansu province were analyzed.The results show that:(1)The frequency of hourly heavy precipitation was high in the east and low in the west in Gansu province,and there were two high centers in the southeast of Longnan and north of Longdong,up to 29 times.(2) The extreme value of hourly heavy precipitation was higher in central and southern regions of Gansu,and decreased to the northwest.The extreme value of precipitation was the highest in southern Gansu province,exceeding 40 mm/h.(3)The frequency of hourly heavy precipitation mainly appeared from July to August,and the rainfall intensity was also the largest in the same period.The frequency of hourly heavy precipitation and hourly rainfall intensity were the strongest in 17:00-24:00,with a peak at 21:00.(4)The diurnal variation of precipitation in different regions was obviously different.The peak of hourly precipitation frequency appeared at 18:00 in Hexi area,at 21:00 in central and southern Gansu,at 22:00 and 19:00 in eastern Gansu and Gannan Plateau respectively.