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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2017-190
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
12 May 2017
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Hydrology and Earth System Sciences (HESS).
Pairing FLUXNET Sites to Validate Model Representations of Land Use/Land Cover Change
Liang Chen1, Paul A. Dirmeyer1, Zhichang Guo1, and Natalie M. Schultz2 1Center for Ocean-Land-Atmosphere Studies, George Mason University, Fairfax, Virginia, USA
2School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA
Abstract. Land surface energy and water fluxes play an important role in land-atmosphere interactions, especially for the climatic feedback effects driven by land use/land cover change (LULCC). These have long been documented in model-based studies, but the performance of land surface models in representing LULCC-induced responses has not been well investigated. In this study, measurements from proximate paired (open versus forest) flux tower sites are used to represent observed deforestation-induced changes in surface fluxes, which are compared with simulations from the Community Land Model (CLM) and the Noah Multi-Parameterization (Noah-MP) land model. Point-scale simulations suggest CLM can represent the observed diurnal and seasonal changes in net radiation (Rnet) and ground heat flux (G), but difficulties remain in the energy partitioning between latent (LE) and sensible (H) heat flux. CLM does not capture the observed decreased daytime LE, and overestimates the increased H during summer. These biases are mainly associated with deficiencies over forest land-cover types and the parameterization of soil evaporation. Global gridded simulations with CLM show uncertainties in the estimation of LE and H at the grid level for regional and global simulations. Noah-MP exhibits a similar ability to simulate the surface flux changes, but with larger biases in H, G, and Rnet change during late winter and early spring, which are related to a deficiency in estimating albedo. Differences in meteorological conditions between paired sites is not a factor in these results. Attention needs to be devoted to improving the representation of surface heat flux processes in land models to increase confidence in LULCC simulations.

Citation: Chen, L., Dirmeyer, P. A., Guo, Z., and Schultz, N. M.: Pairing FLUXNET Sites to Validate Model Representations of Land Use/Land Cover Change, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-190, in review, 2017.
Liang Chen et al.
Liang Chen et al.

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Short summary
This paper evaluates the performance of two commonly used land surface models in simulating deforestation-induced change in surface fluxes using paired FLUXNET observations. Our results highlight the shortcomings in the energy partitioning between latent and sensible heat flux over different land cover types, suggesting the need to improve the representation of surface heat flux processes in land models to increase confidence in LULCC-climate simulations.
This paper evaluates the performance of two commonly used land surface models in simulating...
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