藏北高原土壤湿度时空变化分析  

On spatial and temporal variation of land surface moisture in Northern Tibetan

作　　者：傅新[1,2] 宋春桥[1,3] 钟新科[1,2] 

机构地区：[1]中国科学院地理科学与资源研究所,资源与环境信息系统国家重点实验室,北京100101 [2]中国科学院研究生院,北京100049 [3]香港中文大学地理与资源管理系,中国香港999077

出　　处：《水科学进展》2012年第4期464-474,共11页Advances in Water Science

基　　金：国家自然科学基金资助项目(40971132)~~

摘　　要：使用2009年DOY(Day of Year)145～288时段与2001～2010年夏季(DOY 161～240时段)的Terra/MODIS16 d合成的植被指数产品数据MOD13 A2和8 d合成的地表温度(Land Surface Temperature,TLS)产品数据MOD11 A2,构建TLS～IEV(Enhanced Vegetation Index,IEV)特征空间,从而得到了条件温度植被干旱指数(Temperature Vegetation Drought Index,ITVD)反映的藏北土壤湿度空间分布。对藏北高原2009年植被生长季内土壤湿度的季节性变化及2001～2010年夏季土壤湿度的年际变化特征进行分析,研究结论表明:随着植被盖度的增大,干、湿边斜率逐渐变小,植被对环境温度的变化具有缓冲效应;藏北高原土壤湿度的季节性变化明显,主要受温度、降水、植被覆盖和冻土过程等季节性变化的影响;近10年研究区内土壤湿度有轻微的旱化趋势,但不同气候区内的年际变化表现不一致;气温表现不同程度的显著升温趋势,部分站点的降水有不显著减少趋势,其它站点降水表现为年际波动,而区域统计的ITVD值年际波动与站点气温的变化大体一致。Using the enhanced vegetation index（IEV） and land surface temperature（TLS） dataset derived from the TERRA/MODIS（Moderate Resolution Imaging Spectroradiometer） synthetic products MOD13 A2（16-day composite,in DOY（Day of Year） 161-240 between 2001 and 2010,and DOY 145-288 in 2009） and MOD11 A2（8-day composite,the same items of products with MOD13 A2）,the TLS-IEV two-dimensional characteristic space can be constructed.The ITVD（temperature-vegetation drought index） is then extracted to indicate the top-soil moisture of northern Tibet.The intra-annual and inter-annual variations of soil moisture on the northern Tibetan Plateau are respectively analyzed for the 2009 growing season and the summer seasons（2001-2010）.The results show that the intra-annual variation of TLS-IEV slope and the slopes of dry-edge and wet-edge will be smaller with the increase of vegetation cover,which indicates the buffering effect of vegetation on in environmental temperature changes.The intra-annual variation of top-soil moisture on the northern Tibetan Plateau appears to be significant.The variation is mainly due to the seasonal changes in temperature,precipitation,vegetation cover and frosting and ice-out of frozen soil.The droughty tendency in study area is detected in the variation of soil moisture in the last decade.However,the tendency appears to be varying in different climatic zones of the study area.The mean summer temperatures at seven weather stations in northern Tibet reveal a significant upward trend.The observed precipitation in the eastern region of northern Tibet suggests a slight downward trend.The inter-annual variations of precipitation can be observed at other stations.Furthermore,the inter-annual variability of soil moisture is in agreement with that of mean summer temperatures.

关 键 词：温度植被干旱指数 土壤湿度 中分辨率成像光谱仪 时空变化 藏北高原 

分 类 号：TP79[自动化与计算机技术—检测技术与自动化装置]