三种气象干旱指标在内蒙古地区的适用性分析

Applicability of three drought indexes in Inner Mongolia

用近五年(2006～2010)内蒙古地区的气象观测资料,对降水距平百分率(pa)、相对湿润度干旱指数(M)和标准化降水指数(SPI)三种气象干旱等级指标的适用性进行了对比分析。发现在作物生长季,pa指标和SPI指数对旱情的评判结果高度一致,而冬春季节则是pa指标和M指数的评判结果比较一致。在多雨季节,可能蒸散量通常比同期降水量小,因此M指数对内蒙古夏季旱情评判等级偏低,不宜使用。同时指出应该将不同时间段干旱影响上的差异,以及干旱灾害的累积效应问题,加入到干旱等级指标的改进中。

This research have done the comparative analysis on applicability of three drought indices,which are precipitation anomaly percentage index（Pa）,relative moisture drought index（M）and standardized precipitation index,using meteorological stations data of Inner Mongolia from 2006 to 2010.It is found that the evaluation result of Pa and SPI were extremely consistent in crop growth season,while in winter and spring,the evaluation result of pa and M were relatively consistent.Evaporation capacity in wetter season was always less than the amount of precipitation in the same period.Therefore,index M is comparably unfavorable one since the assessment result of that is lower than actual drought level.Simultaneously,it is indicated that the differences of drought impact at various time stages and the accumulative drought effects should be added to improvement of drought index.