内蒙古中部地区近50a土壤干旱化趋势及其原因  

Drying of Soil in the Central Inner Mongolia Region in the Recent 50-year

作　　者：谢安[1] 刘鸿升[1] 吴长刚[1] 胡豪然[1] 

机构地区：[1]北京大学物理学院大气科学系,北京100871

出　　处：《南京气象学院学报》2004年第4期479-486,共8页Journal of Nanjing Institute of Meteorology

基　　金：国家重点基础研究发展规划项目(G1999043405)

摘　　要：选取内蒙古中部地区为研究对象,在比较实测土壤湿度和NCEP土壤湿度资料的基础上,试用近50a(1950—1999年)的NCEP地表层(0～10cm)土壤湿度(SoilWaterContent,简称SW)资料,分析这一地区表层土壤湿度的变化趋势和干旱化的可能原因。结果表明,这一地区的SW有明显的季节变化,即呈二波型。高SW出现在冬季12月—次年3月(冻土期)和8、9月(雨季)。最干期出现在5、6月,另一干期在晚秋。20世纪60年代中期进入北方干旱化时期,最严重的干旱出现在90年代。周期为20～30a的年代际变化是SW变异中最重要的成分。暖冬可能是表层土壤干旱化最重要的原因,特别是在70年代和90年代,而地表植被的人为破坏,则明显加剧了这种干旱化进程,夏季降雨可能是比较次要的因素。结果还说明,对于我国北方地区,SW是一种可用于描述干旱化大致趋势的物理量。The severe sandstorms encroaching on Beijing in the spring of 2000 were the result of drought over Beijing's upstream area.These make us pay more attentions to the deterioration of the climate environment.In this paper we investigate the possible causes of drought based on the NCEP/NCAR monthly data of volumetric soil water (SW) content at the surface layer(0～10 cm depth) in the central Inner Mongolia region for the period 1950—1999. The results show that SW over the central Inner Mongolia region displays the significant seasonal variation,of a two-wave pattern. High SW occurs in the frozen season (December-March) and rainy season (August-September).Early summer and late fall are the dry season whose SW is very small;May-June is the driest period.The soil in north China has become drying since the middle 1960s with the severest drought period in the 1990s.The interdecadal variability of the period of 20～30a is one of the most important components in SW variations.Warming winters,especially in the 1970s and 1990s may be the most important cause for the drought of surface layer soil in north China.Artificial devastation of surface vegetation expedites the drought course because of increased surface moisture evaporation.Summer precipitation might be the secondary cause for the drought.Our results also demonstrate that the SW can be used as a valuable index for depicting drought.

关 键 词：地表层土壤湿度 土壤干旱化 年代际变化 

分 类 号：S152.7[农业科学—土壤学]