基于格点数据的1961-2012年祁连山面雨量特征分析

Changes of areal precipitation based on gridded dataset in Qilian Mountains during 1961-2012

基于国家气象信息中心发布的全国0.5°×0.5°逐日降水量数据集和气象站点日降水量实测资料,利用主成分分析(PCA)和回归分析,研究了1961-2012年祁连山面雨量年际变化以及面雨量距平与干旱累计强度的关系。结果表明,该套格点数据能够很好地反映出祁连山及其周边区域降水的时空分布格局,山区降水量大于平原区降水量,山区东段降水量大于西段降水量。1961-2012年祁连山面雨量的多年平均值为724.9×108m3,其中,春、夏、秋、冬的面雨量分别为118.9×108m3、469.4×108m3、122.5×108m3、14.1×108m3,夏季面雨量最大,占全年的64.76%。除春季外,其他季节面雨量都呈现逐年增加趋势,夏季增幅最大,平均每年增加1.7×108m3。山区面雨量与祁连山及其周边区域的干湿程度表现出较好的相关性,干旱累计强度与面雨量表现出负相关性,山区面雨量较多时这一地区的干旱强度也较弱。

Based on the 0.5° × 0.5° daily gridded precipitation dataset and observations at meteorological stations released by the National Meteorological Information Center, the interannual variation of areal precipitation in the Qilian Mountains during 1961- 2012 is investigated using principal component analysis（PCA） and regression analysis, and the relationship between areal precipitation anomaly and drought accumulation intensity is analyzed. The results indicate that the spatial distribution of precipitation in the Qilian Mountains can be well reflected by the gridded dataset. The gridded data-based precipitation in mountainous regions is generally larger than that in plain regions. Generally, there is more precipitation in the eastern section of the mountain range than in the western section. The annual mean areal precipitation in the Qilian Mountains is 724.9 × 108m3, and the seasonal means in spring, summer, autumn and winter are 118.9×108m3, 469.4×108m3, 122.5×108m3and14.1 × 108m3, respectively. Summer is a season with most areal precipitation, being approximately 64.76%. The areal precipitation in summer, autumn and winter shows an increasing trend, while spring presents a decreasing trend. Among the four seasons, summer has the largest trend magnitude of 1.7×108m3per year.