On the use of the post-closure methods uncertainty band to evaluate the performance of land surface models against eddy covariance flux data
On the use of the post-closure methods uncertainty band to evaluate the performance of land surface models against eddy covariance flux data
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DOI：
10.5194/bg-12-2311-2015
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发表时间：
2014-12
期刊：
影响因子：
4.9
通讯作者：
J. Ingwersen;K. Imukova;P. Högy;T. Streck
中科院分区：
文献类型：
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作者：
J. Ingwersen;K. Imukova;P. Högy;T. Streck
摘要。涡旋相关（EC）通量数据的能量平衡通常不是封闭的。因此，至少在用于建模时，EC通量数据通常是后封闭的，即对测量的湍流通量进行调整，以关闭能量平衡。然而，就目前的知识水平而言，如何正确地分配缺失能量尚不清楚。由于能量平衡间隙的未知性质，涡流通量数据因此包含一些不确定性，在模型评估和模拟结果解释中应考虑到这一点。我们建议构建关闭后方法不确定带（PUB），该不确定带本质上表示未调整的通量数据与经过三种关闭后方法（Bowen比、潜热通量（LE）和感热通量(H)法）调整的通量数据之间的差异。为了验证这一方法，基于2011年在德国西南部一个冬小麦林分进行的EC测量，对NOAH-MP陆面模型的模拟结果进行了评估，并比较了Jarvis和Ball-Berry气孔阻力方案的性能。LE的PUB宽度高达110 W m−2（占净辐射的21%）。我们的研究表明，考虑由于缺乏能量平衡关闭而引起的EC通量数据的不确定性是至关重要的。仅使用一个后关闭方法可能会导致模型-数据比较中的严重误解。
Abstract. The energy balance of eddy covariance (EC) flux data is normally not closed. Therefore, at least if used for modelling, EC flux data are usually post-closed, i.e. the measured turbulent fluxes are adjusted so as to close the energy balance. At the current state of knowledge, however, it is not clear how to partition the missing energy in the right way. Eddy flux data therefore contain some uncertainty due to the unknown nature of the energy balance gap, which should be considered in model evaluation and the interpretation of simulation results. We propose to construct the post-closure methods uncertainty band (PUB), which essentially designates the differences between non-adjusted flux data and flux data adjusted with the three post-closure methods (Bowen ratio, latent heat flux (LE) and sensible heat flux (H) method). To demonstrate this approach, simulations with the NOAH-MP land surface model were evaluated based on EC measurements conducted at a winter wheat stand in southwest Germany in 2011, and the performance of the Jarvis and Ball–Berry stomatal resistance scheme was compared. The width of the PUB of the LE was up to 110 W m−2 (21% of net radiation). Our study shows that it is crucial to account for the uncertainty in EC flux data originating from lacking energy balance closure. Working with only a single post-closing method might result in severe misinterpretations in model–data comparisons.