1951~2015年我国西北干旱区夏季极端降水的时空特征研究

Study on the Temporal and Spatial Characteristics of Extreme Precipitation in the Arid Region of Northwestern China from 1951 to 2015

基于我国西北干旱区1951~2015年69个气象台站的逐日降水量,用百分位法确定夏季极端降水阈值,采用线性回归方法研究了我国西北干旱区夏季极端降水的时空变化特征,并进一步分析了夏季极端降水量对夏季降水量的贡献。结果表明:(1) 从1951~2015年我国西北干旱区的夏季极端降水量、极端降水强度及极端降水频率总体上均呈现出增加的趋势;从空间分布来看,夏季极端降水量分布存在较为显著的空间差异性,山区的夏季极端降水量、强度大于盆地及平原地区;(2) 1951~2015年夏季极端降水对夏季降水的贡献率呈现下降的趋势,但自90年代后贡献率有所增加;在空间上,在降水较多的山区夏季极端降水量对夏季降水量的贡献率较低,而在盆地及平原贡献率较高。

Based on the daily precipitation of 69 meteorological stations in the arid region of northwestern China from 1951 to 2015, the extreme precipitation threshold in summer was determined by the percentile method, and the temporal and spatial characteristics of extreme precipitation in summer in the arid region of northwestern China was studied using the linear regression, and the contribution of extreme precipitation to precipitation in summer was further analyzed. The results show that (1) the extreme precipitation, extreme precipitation intensity and frequency in the arid region of northwestern China generally showed an increasing trend during 1951-2015, extreme precipitation indicated significant difference of spatial distribution, and the extreme precipitation and extreme precipitation intensity in summer in mountainous areas ware greater than that in basins and plains;(2) The contribution rate of extreme precipitation to precipitation in summer had a declined trend during 1951-2015, while after 1990s, there was an increasing trend, moreover, the contribution rate in mountain area with more precipitation was larger than that in the basins and plains.