近30年来内蒙古地区气候干湿状况时空分布特征

根据内蒙古115个气象站1971～2000年气象资料,采用改进的Selianinov干燥度计算公式,研究了内蒙古地区气候干湿状况时空变化。结果表明:内蒙古干燥度空间分布具有明显地带性分布规律,即从西向东随经度增加干燥度逐渐变小,气候变得湿润。从年际变化的空间分布可以看出,30年来内蒙古地区气候变化大致分为两种类型:1)干湿交替型,位于西部的典型荒漠区和东北部的大兴安岭森林区。2)持续变干型,内蒙古中东北地区的半湿润区和半干旱区的分界线,30年来持续向东南方向推进,使得半湿润区面积缩小,半干旱区面积增加。从年际变化的时间分布来看,70年代,年平均干燥度呈现波动式下降,气候变化趋于湿润化;80年代,气候经历了先干后湿又干的变化过程,干燥度波动较大;90年代,气候经历了先湿润后急剧变干的变化过程,其中1995～2000年干燥度增幅为30年最快的时段。在六大生态类型分区中,典型荒漠区干燥度变化最为剧烈,且对内蒙古全区干燥度的贡献率最大,大兴安岭林区和草甸草原区的干燥度变化最小。从气候干湿状况的年代际变化可以看出,80年代是内蒙古全区气候干旱比较严重的年代。

The characteristics of temporal and spatial distribution of climate dry-wet conditions over Inner Mongolia in recent 30 years

Based on the climate data of 115 meteorological stations covering l971-2000 in Inner Mongolia,and adopting the integrated Selianinov formula,the changes of temporal and spatial distribution of climate dry-wet conditions over Inner Mongolia and six different ecological type regions in different years and decades were studied.The results showed that the spatial distribution of wet and dry conditions had obvious zonal distribution rule,from west to east,AI(Aridity Index) turned gradually to decrease,climate gradually became humid with longitude increasing.Spatial distribution of interannual changes showed that climatic changes of Inner Mongolia approximately had two types: Firstly,alternation of wetting and drying,it was situated western desert region and northeast Daxinganling forest district.Secondly,constantly drying;boundary of subhumid and semiarid region in Inner Mongolia northeast continually extended to southeastward,which made subhumid area decrease and semiarid region increase.Temporal distribution of interannual changes showed that in 70s,annual mean AI took on fluctuating decline and climate changes tended to humidification.In 80s,climate went through the change of drying-wetting-drying,AI fluctuated acutely.In 90s,climate went through firstly wetting and then drying,increasing extent of AI was the fastest in period of 1995~2000.In Six types of ecological regions,as to AI,the most dramatic changes took place in the typical desert region,whose contribution rate was the biggest to Inner Mongolia;the smallest changes appeared in the Daxinanling forest region and meadow grassland region.Interdecadal changes of wet and dry climate conditions showed 80s was a serious drought decade in Inner Mongolia.