以最新的全国土壤水再分析产品为参考，通过最大相关性分析确定最适宜表征湖南省农业干旱的标准化降水蒸散发指数（SPEI)时间尺度，进而分析湖南省1960-2014年农业干旱的时空演变特征。结果表明：全省尺度最适宜表征农业干旱的SPEI时间尺度为SPEF-6；基于SPEF-6表征的全省农业干旱在1960-2014年呈不显著减小趋势，中度及以上干旱的发生频率为14.4%，重度及以上干旱的发生频率为4.9%；在季节分布上，中度及以上农业干旱在冬季发生频率最高，其次为秋季；重度及以上农业干旱亦在冬季发生频率最高，其次为春季；在年代际变化上，农业干旱的发生频率在20世纪60年代最高，而后持续降低，90年代达到最低值，21世纪初又快速升高。

Standard Precipitation Evapotranspiration Index (SPEI) is one of the most w idely used meteorological drought indexes globally for drought monitoring. Determining the appropriate SPEI time scale is the premise of using SPEI for monitoring agri cultural drought. Taken the latest national soil moisture reanalysis products as a rference,the most suitable SPEI time scale for haracderizing agricult ural drought in Hunan Province is det ermined based on maximum correlation analysis and then the spatial and tem poral evolution characteristics of agriultural drought in H unan Province from 1960 to 2014 is analyzed.The results showed that: the most suitable timescale of SPEI to characterize agricultural drought is SPEI6 in the whole province; the agricultural drought characterized by SPEF-6 showed an insignificant decrease trend from 1960 to 2014 in the whole province,the frequency of moderate and severe droughts was 14. 4% on average, and the frequency of severe and extreme droughts was 4.9% on average; in terms of seasonal distribution, moderate and severe droughts have the highest frequency in winter, followed by autumn; severe and extreme droughts also have the highest frequency in winter, followed by spring; regarding interdecadal variations, the frequency of agricultural drought in the whole province was highest in the1960s and then continued to decrease, reaching the lowest value in the 1990s and rapidly increasing in the 2000s.

国家自然科学基金（51979263）；湖南省重大水利科技专项（湘水科技（2015）186-12）