基于涡动相关仪验证的SEBS模型对黑河中游地表蒸散发的估算研究

在我国西北干旱和半干旱地区, 农业收获主要依靠灌溉保证, 灌溉绿洲的蒸散发(ET)是当地水资源的主要消耗. 通过遥感估算区域灌溉绿洲的ET对于地区合理利用水资源极其重要, 利用MODIS/Terra 影像, 基于物理过程的地表能量平衡模型(SEBS), 结合WRF模式输出的气候驱动数据和地面观测数据来估算黑河中游地区的地表通量和日蒸散发(ET_daily). 估算的ET用不同下垫面的涡动相关仪观测数据进行验证, 结果显示: SEBS模型估算的不同下垫面的ET_daily具有很好的拟合效果(R²=0.96, P<0.001), 在灌溉绿洲估算的ET_daily比实测值偏高, 说明干旱、半干旱地区灌溉绿洲土壤水分胁迫是影响ET的主要因素. 模型估算绿洲作物生长期间的ET_daily和实测的ET_daily平均相对误差为12.5%, 精度在观测的能量不闭合误差以内且精度比戈壁和沙漠地区高.

Estimating the evapotranspiration in the middle reaches of the Heihe River by SEBS model based on the eddy covariance system

Irrigated oasis is the primary water consumer in semi-arid and arid regions of Northwest China. Correctly estimating the evapotranspiration (ET) of irrigation oasis through remote sensing is of prime importance for studying the water resources in this region. The Surface Energy Balance System (SEBS) model based on physical processes has been developed to estimate the land surface fluxes by using remotely sensed data and available meteorological observations. In this study, together with MODIS/Terra images, in combination of climate forcing data derived from Weather Research and Forecasting (WRF) model, the SEBS model was utilized to estimate the evapotranspiration and other surface fluxes over the middle reaches of the Heihe River, Northwest China. The estimated daily evapotranspiration (ET_daily) was validated by using measurement of ET with eddy covariance (EC) system in different landscapes (oasis, gobi, and desert). The results show that the estimated ET_daily agrees with the measured ET_daily very well (R²=0.96, P<0.001), and the estimated ET_daily is a little higher than that measured in irrigation oasis, demonstrating soil water stress is the primary factor affecting ET on irrigation oasis in semi-arid and arid regions. The mean error is 0.76 between estimated ET_daily and measured ET_daily in irrigation oasis during crop growth period, with mean relative error of 12.5%, which is better than that in gobi and desert regions.