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西藏中部一江两河地区(包括雅鲁藏布江中游和拉萨河、年楚河中下游地区)是西藏主要的农业区,藏中农业区地表特征参数(地表反照率、地表温度和植被指数)的变化和地表通量的遥感估算对农作物长势监测、农作物估产、灾害监测以及理解农业区内部乃至其与周边地区的能量水循环研究具有重要的意义.选取2003年4月14日和10月16日影像作为春季和秋季代表,利用两种相同空间分辨率的卫星资料———AVHRR和MODIS反演研究区地表特征参数和地表通量.在反演得到地表特征参数的基础上,结合研究区9个台站的地面气象观测资料,利用SEBS模式对该地区地表通量进行了遥感估算.结果表明,研究区地表能量平衡各分量具有明显的空间分布和时间变化特征.同一天中AVHRR和MODIS估算结果空间分布态势保持一致,但由于过境时间的差异,MODIS通量结果均大于AVHRR.
The areas of rivers and one river in central Tibet (including the middle Yarlung Zangbo River and the Lhasa River and the middle and lower reaches of the Nianchu River) are the major agricultural areas in Tibet. The changes of the surface characteristics (surface albedo, surface temperature and vegetation index) Remote sensing estimation of flux is of great significance for the monitoring of crop growth, crop yield estimation, disaster monitoring and understanding of the energy water cycle in agricultural areas and even in the surrounding areas.We selected the images of April 14 and October 16, 2003 as spring and Autumn representative, using two satellite data of the same spatial resolution --- AVHRR and MODIS to retrieve the surface feature parameters and surface fluxes of the study area.On the basis of the inversion of the surface feature parameters and the combination of 9 stations in the study area Ground surface meteorological observation data were used to estimate the surface flux in the area by using the SEBS model.The results show that the spatial distribution and temporal variation of each component of the surface energy balance in the study area have significant spatial distribution.The spatial distribution of AVHRR and MODIS in the same day However, due to the difference of transit time, MODIS fluxes were all higher than AVHRR.