利用SEBAL和改进的SEBAL模型估算黑河中游戈壁、绿洲的蒸散发

蒸散发是干旱、半干旱地区内陆河流域水分消耗的主要途径, 利用遥感估算流域尺度上的蒸散发对内陆河流域水循环和水资源的合理利用具有重要的指导意义. 基于2012年开展的黑河流域生态-水文过程综合遥感观测联合试验(HiWATER)的观测资料和高分辨率的ASTER影像, 分别利用 SEBAL 模型和改进的SEBAL(M-SEBAL)模型估算黑河中游不同时期戈壁、绿洲等不同下垫面的蒸散发, 通过涡动观测数据对比分析了SEBAL模型和M-SEBAL模型估算戈壁、绿洲蒸散发的精度. 结果表明: SEBAL模型在绿洲低估感热通量, 高估潜热通量; 在戈壁高估感热通量, 低估潜热通量. M-SEBAL 模型充分考虑不同下垫面地表辐射温度与植被覆盖度之间的关系, 能很好地反映不同植被覆盖区域的湍流通量的异质性, 估算黑河中游戈壁、绿洲蒸散发的精度高于SEBAL模型.

Simulating the evapotranspiration with SEBAL and Modified SEBAL (M-SEBAL) models over the desert and oasis of the middle reaches of the Heihe River

Evapotranspiration in the arid and semi-arid inland river basins is the main way of water expend. Accurately estimating evapotranspiration based on remote sensing has very important guiding significance for rationally using water resources in these regions. To reduce ambiguity in flux estimation by the Surface Energy Balance Algorithms for Land (SEBAL) due to the subjectivity in extreme pixels selection, in this study, a trapezoidal framework of the temperature-vegetation index space, which involves in the relationship between vegetation fraction of underlying surface and the surface temperature, is used to improve the SEBAL model estimation results. The performances of the SEBAL and the Modified Surface Energy Balance Algorithm for Land (M-SEBAL) in the middle reaches of the Heihe River are compared and evaluated, based on the three Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) images of different growth stages and a network consisting of 20 automatic meteorological meteorological-flux (AMS-EC) stations. All data is acquired in the Heihe Watershed Allied Telemetry Experimental Research. The performances of the SEBAL and M-SEBAL models in the study area show that SEBAL model underestimates the sensible heat flux, but over estimates the latent heat flux in the oasis regions. The M-SEBAL model is able to capture the distinct land surface heterogeneities because of involving temperature-vegetation index. Thus M-SEBAL model can provide more reliable and accurate estimation of ET over desert and oasis rather than SEBAL model.