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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, G01025, doi:10.1029/2007JG000562, 2008

Use of FLUXNET in the Community Land Model development

R. Stöckli

Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
Climate Services, Federal Office of Meteorology and Climatology MeteoSwiss, Zürich, Switzerland
NASA Earth Observatory, Goddard Space Flight Center, Greenbelt, Maryland, USA


D. M. Lawrence

Terrestrial Sciences Section, National Center for Atmospheric Research, Boulder, Colorado, USA


G.-Y. Niu

Department of Geological Sciences, University of Texas at Austin, Austin, Texas, USA


K. W. Oleson

Terrestrial Sciences Section, National Center for Atmospheric Research, Boulder, Colorado, USA


P. E. Thornton

Terrestrial Sciences Section, National Center for Atmospheric Research, Boulder, Colorado, USA


Z.-L. Yang

Department of Geological Sciences, University of Texas at Austin, Austin, Texas, USA


G. B. Bonan

Terrestrial Sciences Section, National Center for Atmospheric Research, Boulder, Colorado, USA


A. S. Denning

Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA


S. W. Running

Numerical Terradynamics Simulation Group, University of Montana, Missoula, Montana, USA


Abstract

The Community Land Model version 3 (CLM3.0) simulates land-atmosphere exchanges in response to climatic forcings. CLM3.0 has known biases in the surface energy partitioning as a result of deficiencies in its hydrological and biophysical parameterizations. Such models, however, need to be robust for multidecadal global climate simulations. FLUXNET now provides an extensive data source of carbon, water and energy exchanges for investigating land processes, and it encompasses a global range of ecosystem-climate interactions. Data from 15 FLUXNET sites are used to identify and improve model deficiencies. Including a prognostic aquifer, a bare soil evaporation resistance formulation and numerous other changes in the model result in a significantly improved soil hydrology and energy partitioning. Terrestrial water storage increased by up to 300 mm in warm climates and decreased in cold climates. Nitrogen control of photosynthesis is revealed as another missing process in the model. These improvements increase the correlation coefficient of hourly and monthly latent heat fluxes from a range of 0.5–0.6 to the range of 0.7–0.9. RMSE of the simulated sensible heat fluxes decrease by 20–50%. Primary production is overestimated during the wet season in mediterranean and tropical ecosystems. This might be related to missing carbon-nitrogen dynamics as well as to site-specific parameters. The new model (CLM3.5) with an improved terrestrial water cycle should lead to more realistic land-atmosphere exchanges in coupled simulations. FLUXNET is found to be a valuable tool to develop and validate land surface models prior to their application in computationally expensive global simulations.

Received 26 July 2007; accepted 21 December 2007; published 19 March 2008.

Keywords: land surface model; land-atmosphere exchange; FLUXNET; terrestrial water storage; soil moisture.

Index Terms: 1631 Global Change: Land/atmosphere interactions (1218, 1843, 3322); 1847 Hydrology: Modeling; 1878 Hydrology: Water/energy interactions (0495); 1848 Hydrology: Monitoring networks; 1626 Global Change: Global climate models (3337, 4928).

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Citation: Stöckli, R., D. M. Lawrence, G.-Y. Niu, K. W. Oleson, P. E. Thornton, Z.-L. Yang, G. B. Bonan, A. S. Denning, and S. W. Running (2008), Use of FLUXNET in the Community Land Model development, J. Geophys. Res., 113, G01025, doi:10.1029/2007JG000562.