近50年内蒙古中东部地区春夏季干旱特征分析

选取内蒙古地区累年平均降水量>200mm的75个气象站点1961～2010年逐日平均气温、逐日降水量资料,基于综合气象干旱指数(CI指数)计算方法,建立了各站历年春季和夏季CI指数序列。利用EOF方法,分析了内蒙古中东部地区春季和夏季干旱的时空分布特征,得出:1)内蒙古中东部地区春旱和夏旱均分为三种类型,且均具有全区一致干旱或不旱型、东西反相干旱型和南北反相干旱型的分布规律。但春季和夏季干旱或反向干旱的中心分布区域略有不同。2)内蒙古中东部地区春季干旱均出现在1980a以前,1980a后全区性的春季重旱减少,但局部重旱有所增加。夏旱在1980a以后呈两年或以上持续发展的态势,且近年来全区性夏旱发生频率增高、强度增加。3)内蒙古地区气候变暖出现在20世纪80年代中期之后。气候变暖后内蒙古地区降水分配格局发生了变化,使内蒙古中东部地区春季干旱减轻,而夏旱加重,应引起相关部门的重视。

Spring and summer drought characteristics in central and eastern Inner Mongolia nearly 50 years

Based on the comprehensive meteorological drought index(CI),using data of daily temperature and precipitation of 75 weather stations which have more than 200mm precipitation a year,CI sequences and spatial and temporal distribution in spring and summer during 1961-2010 were built.It shows that:(1) Drought in spring and summer of central and eastern Inner Mongolia can be divided into three types: drought or not drought all over the central and eastern Inner Mongolia,anticorrelation of east and west part of drought,anticorrelation of north and south part of drought.(2) Drought in spring was reduce after 1980,but regional heavy drought in spring was increase;drought frequency in summer in Inner Mongolia increased.(3) Climate warming began in 1980s.Since then the precipitation distribution changed,which aggravated the summer drought.