针对标准化降水蒸发指数中Thornthwaite方法对干旱区估算误差较大的问题，采用FAO Penman-Monteith方法计算潜在蒸发，改进标准化降水蒸发指数计算方法。应用1961—2013年全国541个气象站点逐日观测资料，从分布检验以及与标准化降水指数、Palmer干旱指数、实测土壤湿度等常用干旱指标一致性校核等方面，评估改进前后标准化降水蒸发指数在区域和季节上的适用性。结果表明：改进蒸发能力计算方法能够显著提高标准化降水蒸发指数的区域和季节适用范围，使标准化降水蒸发指数能够应用于全国不同季节的干旱评估，改进了干旱区标准化降水蒸发指数冬季适用性不高的不足，改进后的标准化降水蒸发指数在年尺度及月尺度上的干旱评估能力均得到改善，满足我国以季节性干旱为主的干旱评估需求。%In view of the question about larger estimate error in arid areas by using the Thornthwaite method of estimating potential evaporation in the process of calculating standardized precipitation evapotranspiration index, we use the FAO Penman-Monteith method instead of Thornthwaite method to improve the method of calculating the standardized precipitation evapotranspiration index. Based on the 1961–2013 daily meteorological data offered by 541 stations of Meteorology Bureau, the distribution of test and standardized rainfall index, Palmer drought severity index and soil moisture are used to analyze the consistency with standardized rainfall evaporation index when used to evaluate drought in the applicability of area and season. Result shows that the improvement on the method of evaporation capacity calculation can significantly expand the application of standardized precipitation evapotranspiration index in area and season, making standardized precipitation evapotranspiration index applied to national drought assessment well, making up the shortcomings in the applicability of standardized precipitation evapotranspiration index in winter at a short time scale level in arid region. In addition, both yearly time scale and monthly time scale of drought assessment ability about modified standardized precipitation evapotranspiration index are improved, meeting the demand for drought assessment in our country, which is given priority to seasonal drought.
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