三种干旱指数对西南地区适用性分析

Analysis of Applicability of Three Drought Indices for Drought Events in Southwest China

利用1951年1月2011年12月中国160个气象站的月降水量和平均气温资料,计算了近61年西南地区18个气象站逐月M指数和季、半年和年尺度的逐月SPI和SPEI指数。参考过去该地区发生的干旱灾害历史资料,研究了三种指数对不同时间尺度干旱的表征能力。结果表明:(1)SPEI指数能抓住降水和蒸发这两个影响干旱的重要决定因素,对西南地区季、半年、年尺度的干旱有较好的表征能力;(2)SPI指数在分析西南地区不同时间尺度干旱时,对年尺度的干旱表征是适用的,对半年尺度的干旱也适用,但表征能力不及SPEI指数,对季节尺度的干旱,春、秋季是适用的;(3)M指数在分析西南地区不同时间尺度干旱时,对年尺度的干旱,部分站点是适用的,对半年尺度的干旱,夏半年是适用的,对季节尺度的干旱,春、夏季是适用的。

Based on the monthly precipitation and temperature data at 18 stations in Southwest China from January 1951 to December 2011,the applicability of the Relative Moisture Index,SPI and SPEI were studied. The monthly Relative Moisture Index,SPI and SPEI at time scales of 3,6 and 12 months for the 18 stations in Southwest China in the past 61 years were calculated. Referencing to historical data of past drought disasters in Southwest China,the comparative study of characterizing drought events at different time scales was done using Mann Kendall and correlation analysis methods. The results show that:( 1) The SPEI not only can grasp precipitation and evapotranspiration which are two important determinant effects of drought,but also is well applicable to characterizing drought events at time scales of 3,6 and 12 months in Southwest China in the past 61 years.( 2)The SPI is applicable to characterizing drought events at time scales of 6 and 12 months,but it is inferior in description to the SPEI at time scales of 6 months. And it is applicable to characterizing drought events at time scales of 3 months both in spring and autumn.( 3) The Relative Moisture Index is applicable to characterizing drought events at time scales of 12 months in some meteorological stations. It is applicable in the summer half year to characterizing drought events at time scales of 6 months. It is applicable to characterize drought events at time scales of 3 months in both spring and summer.