基于东北地区86个国家基本气象站1960-2014年逐月降水量和平均气温数据，计算不同时间尺度下的标准化降水蒸散指数（SPEI），分析不同时间尺度下东北地区季节、年际以及年代际干旱时空分布特征，并与实际干旱成灾面积进行对比分析，验证SPEI在东北地区干旱评估中的适用性。结果表明：春季、夏季和冬季重旱发生频率随时间尺度增大而升高；中旱发生频率随时间尺度增大而降低。近55年东北地区旱涝情势交替出现，干旱频率随年代际变化逐渐升高，干旱程度逐渐加重。整体来看，随时间尺度增加，极旱发生范围逐渐扩大。东北三省在春季、夏季和秋季均有不同频率的干旱事件发生；冬季吉林和辽宁无极旱发生；黑龙江中部无重旱发生。

Based on monthly precipitation and average air temperature data from 86 national meteorological stations during the past 55 years (1960-2014) in the Northeast China, the values of Standardized Precipitation Evapotranspiration Index (SPEI) at various time scales were calculated to represent drought conditions, and the characteristics of spatiotemporal distribution of drought at different time scales in the Northeast China were analyzed. The calculation results were compared with the actual drought area data to verify the applicability of the SPEI to the drought assessment of the Northwest China. The results showed that the frequency of severe droughts in spring, summer, and winter would increase with the increase of the time scale, whereas the frequency of medium droughts would decrease with the increase of the time scale. Droughts and floods in the Northeast China occurred alternatively during the recent 55 years. The frequency and intensity of drought increased gradually on a decadal basis. Generally speaking, the scope of extreme droughts would gradually expand with the increase of the time scale. Droughts occurred at different frequencies in spring, summer, and spring in the Northeast China. No extreme drought occurred in winter in Jilin and Liaoning provinces. No severe drought occurred in the middle of Heilongjiang province.

水利部公益性行业科研专项经费项目资助(201401036); 国家自然科学基金资助项目(51309010)