2种标准化干旱指标在甘肃武威干旱监测中的对比

摘要

以甘肃武威1961 ～2010年逐日降水及温度资料为基础,分析比较了标准化降水指标(SPI)和标准化降水蒸散指标(SPEI)对武威干旱监测的异同.结果表明1961～1998年当气温距平为负值时,SPEI与SPI对干旱的监测结果差异不大,这二者在不同时间尺度下对干旱的反映具有很好的一致性,而且诊断结果与降水量距平百分率所得结论基本相同,均能够与统计的实际干旱发生情形相对应.但在1998年之后,随着武威市温度明显升高,显著大于多年平均值,蒸发明显增大,干旱的发生发展状况不仅仅依赖于降水时,SPEI对干旱等级的划分要重于SPI对干旱的诊断结果,进一步分析干旱事实,发现SPEI对干旱的反映更接近实际状况.研究结果表明SPEI更关注以水分平衡为基础的区域水分供给状况,因而更能有效地反映出气候变暖背景下的干旱发生发展状况,可以为我国不同时间尺度下干旱的及时诊断提供依据.%Drought is one of the most costly natural disasters in the world,the assessment of its severity,frequency and duration is necessary and important for all human being and society.In this study,the daily precipitation and temperature data from 1961 to 2010 were used to analyze and compare the difference between SPI and SPEI in their monitoring of the drought conditions in Wuwei of Gansu Province.The results show that when temperature anomaly was negative during 1961-1998,SPI and SPEI had identical values and they could be used to assess drought duration and severity in Wuwei,and they had good relationship with percentage of precipitation anomalies.However,when temperature increased after 1998,the SPEI was higher than SPI due to the impact of evapotranspiration on SPEI,SPEI could monitor some severe drought events during 1998-2010,but SPI could not.The results indicate that SPEI takes the input and output of water depended on water balance into account in a specific research area,so it can monitor drought events efficiently in the context of global warming.