温带阔叶红松林生态系统潜热通量模拟——气孔导度组合模型在Shuttleworth-Wallace双源模型中的应用

叶片水平的气孔导度组合模型已被成功扩展到冠层水平,并被应用于冬小麦生态系统潜热通量的模拟研究,但该研究仅基于1a的数据,有必要研究模型在更长时间尺度和其它生态系统类型的适用性.以长白山阔叶红松林(CBS)为研究对象,将组合模型进一步应用于Shuttleworth-Wallace双源模型,模拟了CBS 3a生长季内的潜热通量,利用涡度相关系统观测的潜热通量数据对模型进行验证,并对比了双源模型与单源模型的模拟结果.结果显示,双源模型较单源模型能取得更高的模拟精度,生长季不同时期的潜热通量模拟值和实测值的日变化较一致.对双源模型模拟值和实测潜热通量的相关分析显示,二者直线回归斜率和R2分别为0.96和0.72.对长白山阔叶红松林生态系统的蒸散和植被蒸腾的季节和年际变异分析发现,影响冠层蒸散和植被蒸腾季节动态的主要因素是饱和差和辐射,而影响它们年际动态的主要因素则是饱和差和温度.

Simulation of latent heat flux over a temperate mixed forest: application of a combination model to Shuttleworth-Wallace model

A leaf-scale combination model has been successfully scaled up to canopy level and coupled with single source model (SSM) to estimate canopy-scale latent heat flux (λE) of winter wheat based on one year data.It is necessary to study the applicability of the combination model at longer time scale and for other ecosystems.In this study the combination model was used as the stomatal conductance sub-model in Shuttleworth-Wallace (S-W) model,which is a widely used dual source model (DSM).We applied the S-W model to estimate diurnal patterns of λE over a temperate mixed forest at Changbaishan (CBS) in Northeast China.Measured λE data from the eddy covariance (EC) system were used for model validation.Diurnal variation of estimated λE is in good agreement with that of measured λE.Simulated results of SSM and S-W model were compared and the S-W model exhibits better simulation than SSM.The slope and R2 of the line regression between the S-W model simulated and observed λE are 0.96 and 0.72 (n=8519),respectively.The results show that dominant factors controlling the variation in ecosystem evapotranspiration (ET) and vegetation transpiration (Tr) at CBS are different at seasonal and inter-annual time scales.Vapor press deficit (D) and photosynthetically active radiation (Qp) are the dominant factors for the seasonal variation of ET and Tr,while the differences in D and temperature determine their inter-annual variation.