锡林郭勒盟气候干燥度的时空变化规律

The analysis on the spatial-temporal change of climate aridity in Xilinguole Steppe

以锡林郭勒盟15个气象站点1981—2007年的月平均气温、月累积降水量数据为基础,在Arcgis软件的支持下,得到DeMartonne干燥度的空间数据。研究结果表明,锡林郭勒盟27a平均干燥程度自东向西递增;1981—2007年,锡林郭勒盟整体上表现出干燥度数值下降、干旱程度上升的趋势;从干燥度的年代,20世纪80年代和90年代是锡林郭勒盟气候相对湿润时期,21世纪初期,锡林郭勒盟大部分地区的气候呈现干燥度值减小、干燥程度加大的趋势,干性干旱区在空间分布上占据了主导地位,结果也打乱了原有的气候带状交替格局。21世纪初与20世纪80年代相比,各干燥度等值线的位置均发生了明显的东移现象。

1980＇s,the serious arid area with dryness index below 10 didn＇ t exist in Xilinguole League.The dominant climate zone was the moderate arid one which accounted for 40.63% of the total area,at the same time,wet arid zone made up nearly 20% of its total;Into the 90＇s,dry and moderate arid areas slightly reduced,but wet arid areas increased to 21.58% and the drought wet areas took up 11.90% ;The early 21st century,the climate for most parts of Xilinguole League showed a general tendency with Idm value declining and drought degree rising,dry arid zone occupied a dominant position on the spatial distribution,and the original climate pattern with alternate strips was broken,too.Along with the temporal process,the spatial range of different aridity classes had changed and the changes were particularly notable in the 21st century.Compared with 1980＇ s,the position of three aridity contours of 22.5,25 and 30 had shifted westward slightly,respectively moved for 0.27,0.05 and 0.25 longitudes in 1990＇s,and the displacement for each aridity class was more obvious in the early 21st century.The position of five aridity contours of 15,20,22.5,25 and 30 were shifted eastward for 1.13,2.66,1.81,0.8 and 1.23 longitudes.All of these results showed that the climate in Xilinguole League had a tendency with aridity degree increased since the beginning of 21st century,and the spatial range for each aridity class took place significant displacement eastward.