标准化降水蒸发指数在中国区域的应用

Application of Standardized Precipitation Evapotranspiration Index in China

利用中国气象局160个站1951~2010年月降水和月平均气温资料,分析了最近定义的一种干旱指数——标准化降水蒸发指数（SPEI）在我国不同等级降水区域的适用性,并与标准化降水指数（SPI）和湿润指数H进行了对比分析。结果表明：1）在我国年均降水量大于200 mm的地区,各种时间尺度的SPEI分析均适用;在干旱区（年均降水量小于200 mm）,只有12个月以上的大尺度SPEI分析适用性较好;其中12个月尺度的SPEI分析在各区适用性最好。2）由于干旱区冬季的潜在蒸发量和降水量0值均较多,导致1、3、6个月的小尺度SPEI分析在该区不适用。3）与SPI和H指数相比,SPEI既能充分反映1997年气温跃变以后增温效应对干旱程度的影响,又可作为监测指数识别干旱是否发生和结束,能较准确地表征干旱状况。

Applicability of the standardized precipitation monthly precipitation and monthly-mean temperature data indicate that the SPEI at multiple time scales can be used evapotranspiration index （SPEI） is examined on the basis of recorded by 160 stations in China from 1951 to 2010. Results to examine drought in areas with annual precipitation greater than 200 mm. In other regions, the index is effective for time scales longer than 12 months. In addition, the lack of precipitation and evapotranspiration during winter months results in reduced confidence of SPEI values when applying 1-, 3-, and 6-month SPEIs in arid climatic regimes with annual precipitation less than 200 mm. Moreover, time series of SPEI, standardized precipitation index （SPI）, and H index were compared for two observatories with different climate characteristics located in various regions of China. Of the three indices, only the SPEI was able to identify an increase in drought severity associated with higher water demand as a result of evapotranspiration under global warming. Further, the SPEI was able to determine the beginning and end of drought events. Therefore, SPEI carries an advantage when used for drought analysis and monitoring.