锡林郭勒草原区气候干旱化的时空变化规律

Temporal and Spatial Changes of Climate Aridity in Xilinguole Steppe Region

气候干湿变化是影响草原区植被与环境状况的重要因素.应用1981-2007年锡林郭勒盟的年平均气温和年降水量数据,计算出De Martonne干燥度指数Idm的栅格空间数据,把干燥度作为衡量区域气候干湿状况的综合指标,对锡林郭勒盟1981-2007年的气候状况进行了分析,同时分析了气候干燥度等值线的空间位移与动态变化规律.研究结果表明:(1)锡林郭勒盟的干燥度指数呈现自西向东逐渐递增的空间变化规律,1981-2007年间干燥度值总体上呈现波动中下降的趋势;(2)锡林郭勒盟27年干燥度平均值的空间变率存在显著的区域差异,在116°E以西地区,干燥度值随经度东移缓慢提高,而在117°30′E以东地区,则迅速提高;(3)20世纪的80、90年代,锡林郭勒盟的干燥度平均值接近,且与27年总体变化规律基本相同;进入21世纪以后,气候干旱化程度显著提高,相同干燥度区间的位置明显东移.

Drought-wet change of climate has a strong influence on the status of vegetation and environment in the steppe region.Based on the precipitation and temperature data of Xilinguole from 1981 to 2007,De Martonne Aridity index（Idm,the higher the value is,the wetter the climate is）is calculated and taken as a comprehensive index for measuring the aridity status of climate.Climate conditions of Xilinguole from 1981 to 2007 are analyzed,and temporal and spatial changes of climate aridity are studied.The results showed that：Firstly,the aridity indexes increase gradually from west to east in the geographic space of Xilinguole,and the aridity indexes of Xilinguole from 1981 to 2007 decreased with fluctuation;Secondly,average values of aridity indexes from 1981 to 2007 present a remarkable regional difference in Xilinguole,in the region west of longitude 116°E,the aridity indexes increased slowly from west to east,but in the region east of longitude 117°30′E,the aridity indexes increased rapidly from west to east;Thirdly,the aridity indexes of 80＇ and 90＇ are approximatively equal,and they have the same regulation with the aridity indexes of 27 years;Since 21century,the climate aridity of Xilinguole is promoting obviously,and the areas with the same interval of aridity indexes have moved eastward.