甘肃省汛期逐小时降水量分布及变化特征

Distribution and Variation Characteristics of Hourly Precipitation in Flood Season in Gansu Province

摘要: 利用甘肃省71个国家气象站1975~2016年主汛期(5~9月)逐小时降水量数据，采用线性趋势分析、空间插值等方法，分析了甘肃省42年来的逐时降水量时空分布和变化规律。结果表明：1) 不同代表站的降水量在一日内的分布状况极为不均匀，总体来看，全省各站点小时降水比率低值区集中在11~17时，高值区出现18~23时；2) 从降水频率分布来看，频率大值区都位于河东地区，各个时次的最小降水频率均出现在河西走廊的敦煌(13时最小降水频率为敦煌、酒泉、高台三站同时保持)。各个时段沿河西走廊有西北到东南的方向，从敦煌至武威降水频率呈递增趋势；3) 三个气候区降水比率与降水频率在一日内的气候倾向率保持一致，且降水频率变化趋势线普遍滞后于降水比率变化趋势线。全省降水量在午前与午后分布规律性较强，具体表现为：5~8月份，午前降水量在一日中所占的比例大，而在9月份恰恰相反，表现为午前降水量大于午后降水量。

Abstract: Based on the hourly precipitation data of 71 national meteorological stations in Gansu Province during the main flood season (May to September) from 1975 to 2016, the temporal and spatial distribution and change law of hourly precipitation in Gansu Province in the past 42 years are analyzed by using the methods of linear trend analysis and spatial interpolation. The results show that: 1) The distribution of precipitation at different representative stations in a day is very uneven. On the whole, the low value area of hourly precipitation ratio of stations in the province is concentrated at 11~17 hours, and the high value area appears at 18~23 hours; 2) From the distribution of precipitation frequency, the high frequency areas are located in Hedong area, and the minimum precipita-tion frequency of each time occurs in Dunhuang in Hexi Corridor (the minimum precipitation fre-quency at 13:00 is maintained at Dunhuang, Jiuquan and Gaotai stations at the same time). In each period, there is a northwest to southeast direction along the Hexi Corridor, and the precipitation frequency shows an increasing trend from Dunhuang to Wuwei; 3) The precipitation ratio in the three climatic regions is consistent with the climate tendency rate of precipitation frequency in one day, and the change trend line of precipitation frequency generally lags behind the change trend line of precipitation ratio. The distribution regularity of precipitation in the whole province is strong in the morning and afternoon. The specific performance is as follows: From May to August, the proportion of precipitation in the afternoon in a day is large, while in September, it is just the opposite, showing that the precipitation in the afternoon is greater than that in the afternoon.