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Title: EVALUATION OF A LAND SURFACE MODEL FOR SEMI-ARID ENVIRONMENTS 1593

Author
item HOGUE, T. - UCLA
item BASTIDAS, L. - UTAH STATE UNIVERSITY
item GUPTA, H. - UNIVERSITY OF ARIZONA
item SOROOSHIAN, S. - UNIVERSITY OF CALIFORNIA
item MITCHELL, K. - NOAA/NWS
item Emmerich, William

Submitted to: Journal of Hydrometeorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2004
Publication Date: 2/5/2005
Citation: Hogue, T.S., Bastidas, L., Gupta, H., Sorooshian, S., Mitchell, K., Emmerich, W.E. 2005. Evaluation of a land surface model for semi-arid environments Journal of Hydrometeorology 6(1): 68-84.

Interpretive Summary: Land-surface models that model energy and water exchange within climatic regions are needed to be able to predict the effect of climate change. A model was calibrated and tested in one semi-arid region and then evaluated in another. The calibrated model did well in estimating energy and water exchange, except when there was a large input of monsoon moisture into the region. The use of the model in similar regions from which it was calibrated decreased its predictive ability. The benefit of this work was to advance model development for use in long-term climate change studies.

Technical Abstract: There exists a multitude of land-surface models which vary considerably in terms of complexity and sophistication of biophysical processes. Variations arise from differences in representation of physical processes, specification and calibration of parameters and land surface characteristics, and initialization of prognostic land states. The utility of these models for regional or global simulations is strongly linked to their ability to simulate physical (energy, water, and chemical) processes in distinct hydro-climatic regions, and their ability to capture changes due to fluctuations in climate forcings. This analysis tests the transferability of a land-surface model for semi-arid regions using a multi-objective, systematic evaluation scheme. This work is partly based on the framework for the PILPS San Pedro-Sevilleta experiment for semi-arid regions. The NCEP Noah model, chosen for this study, is able to simulate sensible heat, ground heat, and ground temperature observations with a high degree of accuracy for the sites using optimized parameter sets. However, there is a large influx of moisture during the monsoon period and significant latent heat flux errors are observed in model simulations during these periods. The use of proxy site parameters (direct application of a parameter set from a 'similar' climatic regime), as well as traditional default parameters, result in a diminished model performance over a parameter set calibrated specifically to the flux sites. In general, there is still opportunity for improvement in the representation of physical processes in land-surface models for semi-arid regions. The hope is that rigorous model evaluation such as that put forth in this analysis, and studies such as the PILPS San Pedro-Sevilleta, will lead to advances in model development and parameter estimation for use in long-term climate and regional environmental studies.