1960-2012年甘肃黄土高原干旱时空变化特征分析

基于甘肃黄土高原区12个测站1960-2012年的气象资料，利用标准化降水蒸散指数对该区近53a四季干旱的时空变化特征进行了分析。结果表明：甘肃黄土高原区近53a的四季均呈干旱化趋势，以秋季最为突出，春季次之。经过Mann-Kendall趋势分析法检验，秋旱最显著的地方是兰州、靖远及环县；春旱最明显的地方是崆峒、庆阳和西峰；冬季有变湿的趋向，但未通过显著性水平。空间分布上，甘肃黄土高原区腹部比边缘区发生干旱的频率高，山地比谷地发生干旱的频率高。陇中地区夏旱频发，陇东地区冬旱频繁。干旱变幅最大的地方是研究区西北的乌鞘岭和东北的子午岭。近53a研究区干旱事件发生频次呈增长趋势，近10a来尤为显著。中度干旱发生频次的增长速度比极端干旱事件增长的快，但没有极端干旱事件显著。

The Temporal and Spatial Distribution of Drought on The Loess Plateau Based on the Standardized Precipitation Evapotranspiration Index from 1960 to 2012

Using meteorological data collected from 12 stations across the Loess Plateau, Gansu, China from 1960 to 2012, we analyzed variation in drought temporal characteristics and the spatial distribution and frequency of drought based on the standardized precipitation evapotranspiration index. We found that autumn is the most prominent season for drought, followed by spring. According to Mann-Kendall trend analysis, the most significant drought locations in autumn are Lanzhou, Jingyuan and Huanxian. The most obvious drought locations in spring are Kongtong, Qingyang and Xifeng. The frequency of drought in the midland region of the plateau is higher than the border;and similarly the mountain region is higher than the valley. The most drought-prone location in spring is around Liupanshan Mountain;in summer it is the mountain region of Longzhong;in autumn it is south of 36°N;and in winter it is the mountain region of Jingyuan, Yuzhong and Minxian. The mountains of Wushaoling and Ziwuling in the northwest show the greatest luffing of drought. In our 53 year sample, the drought event frequency increased and is particularly significant in the last decade. Although the frequency of moderate drought is growing faster than the growth in extreme drought events, the latter is more prominent.