【摘要】 为了研究非均匀地表的蒸散特征,结合地面气象资料,考虑地形效应增加了坡地辐射计算方法,结合Landsat 8波段特征构建双层蒸散发遥感模型。以北京市西北方位的水源上游区为例,进行了蒸散发的估算、验证与分析。估算结果与地表通量站实测值对比发现,感热通量和潜热通量的平均误差分别为4.12%和8.36%,确定系数为0.82和0.98,相关关系较强;与坡地日蒸散发观测数据对比,平均相对误差为8.12%,均方根误差为0.35 mm/d,具有较好的估算精度。结合土地利用探讨了水热通量、蒸散发的空间分布情况,同时分析了蒸散发与坡面地形之间的关系:坡度小于35°时,随坡度上升,日蒸散发有较为明显的增加趋势;当坡度大于35°时,受植被覆盖率影响,各季节代表日的日蒸散发呈现不同的变化趋势。各季节代表日蒸散发与坡向同样存在较为显著的相关关系,趋势线呈反抛物线。更多还原

【Abstract】 In order to study the evapotranspiration characteristics of the non-uniform surface,combined with the surface meteorological data,the slope radiation calculation method is added for considering the topographic effect,and the two-layer remote sensing model of evapotranspiration is constructed by combining the features of Landsat8 band. Evapotranspiration is estimated,verified and analyzed with the upstream area of northwest water source of Beijing as an example. The comparison between the estimated results and the measured values of surface flux stations shows that the average errors of sensible heat flux and latent heat flux are 4. 12% and 8. 36% respectively,and the determination coefficients are 0. 82 and 0. 98,respectively. Compared with the daily evapotranspiration observation data of the slope,the average relative error is 8.12%,and the root-mean-square error is 0.35 mm/d,which has good estimation accuracy. The spatial distribution of water heat flux and evapotranspiration is discussed in combination with land use. The relationship between evaporation and terrain slope is also analyzed. It is found that when the slope is less than 35°,the evaporation has more obvious increasing trend with the increase of slope;when the slope is greater than 35°,affected by the vegetation coverage,the evaporation of each season presents different trends. There is also a significant correlation between diurnal evapotranspiration and slope direction in each season,and the trend thread is an inverse parabola.更多还原