考虑地表反照率时域重建的海河流域蒸散发模拟研究

Estimation of evapotranspiration considering land surface albedo reconstruction in Haihe river basin

地表反照率(a_(c))是计算辐射收支分配的重要参数,其精度对实现大尺度地表蒸散发(ET)的准确模拟有重要意义,在ET模拟中常用线性插值法来获取时间连续的a_(c)数据,但其a_(c)重建过程的机理性不足。本研究利用时域重建方法获取a_(c)的逐日数据,利用Penman-Monteith-Leuning(PML)模型对海河流域ET进行了模拟,并与传统的基于线性插值计算a_(c)的方法进行对比,分析了不同a_(c)输入对ET模拟结果的影响。结果表明:(1)采用时域重建方法得到的a_(c)进行ET模拟时,在海河流域与2008、2010及2018年4个涡度相关数据的相关系数均在0.53以上,相关性较好;(2)海河流域2018年的a_(c)呈现出北高南低的特征,同时夏季和冬季的高值区相对较小;(3)望都站的示例分析表明,与采用线性插值得到的a_(c)方案相比,对a_(c)进行时域重建后进一步降低了ET模拟值的均方根误差和偏离度,可为提高蒸散发精度提供借鉴。

Land surface albedo(a_(c))is a crucial parameter for the radiation allocation.It is important for the accurate simulation of evapotranspiration(ET)in large scale.In the ET simulation,daily ac data are often derived with linear interpolation method,which is deficient in physical principle.In this research,the daily ac data are reconstructed with image restoration method and the ET of the Haihe river basin is calculated with Penman-Monteith-Leuning(PML)model.The linear interpolation method is compared to evaluate the influence of ac on ET.The results show that:(1)the ET results obtained by reconstructed ac show good performance in the Haihe river basin,and the correlation coefficients of four eddy covariance stations in 2008,2010 and 2018 are larger than 0.53;(2)the ac of Haihe river basin in 2018 shows that ac is larger in the northern part whereas it’s smaller in the southern part.In addition,the high value areas are relatively small in summer and winter;(3)the experimental analysis of Wangdu station shows that,comparing with the results derived with linear interpolated ac,the reconstructed ac reduces the RMSE and Bias of simulated ET.The study can provide reference for evapotranspiration estimation.