基于TSEB模型的黄河三角洲蒸散量估算

蒸散发作为湿地生态系统中地-气间水热交换的主要方式,很大程度上影响着湿地的水热平衡,合理准确地估算蒸散发量,对湿地生态系统的水分循环、能量平衡以及科学管理具有重要意义。黄河三角洲湿地作为世界上暖温带最广阔、最完整和最年轻的河口湿地生态系统,既是气候变化的敏感区,也是生态环境的脆弱区。针对其地理位置特殊、水资源供需矛盾尖锐等特点,利用SEBAL(Surface Energy Balance Algorithm for Land)和TSEB(Two-Source Energy Balance)模型,对黄河三角洲湿地蒸散发量进行估算:首先利用SEBAL模型计算地表的特征参数和各地表通量,然后利用TSEB模型分离土壤和植被,分别计算黄河三角洲湿地瞬时的土壤蒸发、植被蒸腾和土壤植被总蒸散发量,利用积分关系法进行时间尺度转换,得到日蒸散量。利用气象站实测蒸发值和FAO Penman\|Monteith公式计算的作物系数,对遥感估算结果进行直接和间接精度评价。结果表明反演的蒸散发结果合理,精高较高。分析蒸散的空间分布及不同地表类型的蒸散特性,对比分析芦苇沼泽和芦苇草甸的不同蒸散特点,结果表明基于两模型耦合的方法可用于黄河三角洲湿地蒸散量估算。

Estimation of Evapotranspiration in Yellow River Delta Wetland based on Two=Source Energy Balance (TSEB) Model

Evapotranspiration(ET)as the main form of exchanges between the water and heat to the soil—atmosphere of the wetland ecosystem greatly affects the water thermal equilibrium.Estimation of the evaporation quantity reasonably and accurately is one of great significance to study hydrologic recycle,energy balance and scientific management of the wetland ecosystem.Wetland in Yellow River Delta(YRD),which is the most integrated,broadest,youngest wetland ecological system in warm temperate zone of the earth,is not only sensitive to climate change,but also fragile to the environment change.Remote sensing technique was used to estimate ET in YRD in our case study.Coupling the model of Surface Energy Balance Algorithm for Land(SEBAL)and Two-Source Energy Balance(TSEB),SEBAL was used to calculate land surface characteristic parameters and flux,and TSEB was used to calculate vegetation transpiration,soil evaporation and total ET separately of YRD by Considering the inner structure of the surface layer which could be divided into two sub layers representing soil and vegetation.Actual evapotranspiration of the study area was meatured from stations and calculated with Penman-Monteith equation to compare with results from remote sensing,which showed that the result is reasonable.Then the spatial distribution of the daily ET was analyzed and the characteristics of ET with different features,especially with the typical vegetation of reed marshes and meadows,were also analyzed to help realize the wetland conditions.The results illuminates that daily ET estimated is reasonable.The method can be used for the accurate estimation of ET in YRD.