摘要
水分是衡量植被生理状态和形态结构的重要参数。青藏高原在区域生态环境和全球气候变化等方面扮演重要角色,但对其在植被含水量时空变化动态及其与气候的关系方面缺乏系统研究。基于236个地面样方实测数据和AMSR-E每日亮温数据,利用留一法交叉验证方法确立了青藏高原植被含水量的遥感反演模型。同时,估算了青藏高原植被含水量空间分布,分析了2002-2010年植被含水量的时间动态及其与气候变化的关系,结果表明,1）微波极化指数（MPI）优于微波植被指数（MVI）,18GHz的MPI乘幂模型AWC=128.93×MPI-0.67可以很好地反映植被绝对含水量（AWC）空间变化动态;2）青藏高原7月份日植被含水量由西北向东南呈带状递增的趋势。其中,西北部至中部的大部分地区植被含水量主要集中在800kg/hm2以下,东南部植被含水量较西北地区明显增加,主要集中在800~4 000kg/hm2之间;3）多年平均月际间的植被含水量存在明显的空间异质性,其变差系数具有由西向东逐渐增加的趋势;4）温度和降水与植被含水量之间具有一定的相关关系,其中降水对植被含水量的影响存在明显的滞后性。
Water is an important parameter governing vegetation physiological status and formation structure. The Qinghai--Tibetan Plateau plays an important role in the regional ecological environment and global climate changes, but there is a lack of research on spatial temporal variation of vegetation water content and the rela- tionship between water content and climatic factors. Using the Leave One Out Cross Validation （LOOCV） method, an inversion model of vegetation water content was established in the Qinghai--Tibetan Plateau region based on 236 observed data with corresponding AMSR-E daily brightness temperature data. By simulating the distribution of water content in the Qinghai--Tibetan Plateau, the dynamic variations of vegetation water con- tent and the relationship between water content and climatic factor were analyzed from 2001 to 2010. The Mi- crowave Polarization Index （MPI） is superior to the microwave vegetation index in this region, and the power model based on 18 GHz MPI AWC=128.93XMPI-0.67 has the highest accuracy, and better reflects the condi- tion of the Absolute Vegetation Water Content （AWC）. Daily vegetation water content of the Qinghai-Tibet- an Plateau in July shows a belt with an increasing trend from northwest to southeast, in which the vegetation water content is mainly below 800 kg/ha in the western and central regions. Compared with the northwest, the southeast vegetation water content has an increased trend, monthly variability of vegetation water content has obvious mainly between 800 and 4 000 kg/ha. The inter- spatial differences in recent years which increases from west to east on the Qinghai--Tibetan plateau. Some relationships between temperature, precipitation and the vegetation water content, show a hysteresis response to rainfall
出处
《草业学报》
CSCD
北大核心
2013年第5期1-10,共10页
Acta Prataculturae Sinica
基金
国家自然科学基金项目(30972135,41071342)
教育部高等学校科技创新工程重大项目培育资金项目(708089)
国家科技支撑计划项目(2009BAC53B01)资助
关键词
青藏高原
微波指数
植被含水量
时空变化
留一法
Qinghai--Tibet Plateau
microwave index
vegetation water content
spatio-temporal variation
Leave One Out Cross Validation （LOOCV）
