基于双层模型的沙河流域蒸散发定量遥感估算

论文以北京市沙河流域为研究区,选择1999-2007年不同季节典型日的TM/ETM+数据,辅助相关气象观测资料,以地表蒸散发遥感反演双层模型为基础,构建了估算沙河流域地表日蒸散发反演系统。该系统包括三部分:基于双层模型的蒸发比估算;日净辐射总量估算;基于蒸发比不变法的日蒸散发估算。模拟的典型日序列中,春季晴日流域日均蒸散发约为2.28 mm、夏季2.97 mm、秋季1.59 mm、冬季0.5 mm;以林地为主的流域上游山区日蒸散发普遍高于以居民地和农田为主的下游平原区,上下游春、秋、冬季空间差别较大,夏季较小。估算结果与贾贞贞等、徐自为等利用大孔径闪烁仪和涡动相关仪的观测值对比,相对误差介于0到16%之间,平均相对误差为11.1%,均方差为0.77 mm,精度较高。

The Regional Evapotranspiration Estimation Using A Two-layer Model Based on Quantitative Remote Sensing in Shahe River Basin

Based on the TM/ETM+ data and relevant meteorological data for typical days in different seasons during 1999-2007 in Shahe River Basin, we developed the land-surface evapotranspiration (ET) remote sensing retrieval system to estimate the daily ET in Shahe River Basin. The system is based on the two-layer ET model of quantitative remote sensing, which includes three parts: inversion of the evaporation ration using two-layer model, calculation of total daily net radiation, and estimation of daily ET based on evaporation fraction method. The results show that the average daily ET of the typical days is about 2.28 mm in spring, 2.97 mm in summer, 1.59 mm in autumn, and 0.5 mm in winter. The ET of upstream areas covered by forest is higher than that of the downstream plain covered by settlements and farmland. In summer the difference of ET between the upper reaches and lower reaches is smaller compared to the other three seasons. Using the large aperture scintillometer and eddy correlation instrument, Jia, Xu, et al. got some observed values of ET in the Shahe River Basin. By comparing the observed data with the estimated data, we found the estimation system had a high precision with the relative error between 0 and 16% (mean error of 11.1%), and the variance of 0.77 mm.