Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 8
Biogeosciences, 12, 2311-2326, 2015
https://doi.org/10.5194/bg-12-2311-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 12, 2311-2326, 2015
https://doi.org/10.5194/bg-12-2311-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 17 Apr 2015

Research article | 17 Apr 2015

On the use of the post-closure methods uncertainty band to evaluate the performance of land surface models against eddy covariance flux data

J. Ingwersen1, K. Imukova1, P. Högy2, and T. Streck1 J. Ingwersen et al.
  • 1Institute of Soil Science and Land Evaluation, Universität Hohenheim, 70593 Stuttgart, Germany
  • 2Institute of Landscape and Plant Ecology, Universität Hohenheim, 70593 Stuttgart, Germany

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.

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The energy balance of eddy covariance (EC) flux data is normally not closed. Therefore, EC flux data are usually post-closed, i.e. the measured turbulent fluxes are adjusted so as to close the energy balance. We propose to use in model evaluation the post-closure method uncertainty band (PUB) to account for the uncertainty in EC data originating from lacking energy balance closure. Working with only a single post-closing method might result in severe misinterpretations in model-data comparison.
The energy balance of eddy covariance (EC) flux data is normally not closed. Therefore, EC flux...
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