Impact of model structure and parameterization on Penman–Monteith type evaporation models

• Published in: Journal of hydrology (Amsterdam) 2015-06, Vol.525 (C), p.521-535
• Main Authors: Ershadi, A., McCabe, M.F., Evans, J.P., Wood, E.F.
• Format: Article
• Language: English
• Subjects: Aerodynamic resistance; Aerodynamics; Evaporation; Evapotranspiration; Flux; Forests; Grasslands; Hydrology; Latent heat flux; Mathematical models; Parametrization; Penman–Monteith; Surface resistance
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2015.04.008

•Evaluated three Penman–Monteith type models with multi-year data from 20 flux towers over 5 biomes.•Fourteen unique model configurations were developed to identify impact of resistance schemes.•No particular model configuration consistently outperformed others.•Considerable model variability was observed both within and between different biomes.•Results provide guidance on model selection and performance across typical biome types. The impact of model structure and parameterization on the estimation of evaporation is investigated across a range of Penman–Monteith type models. To examine the role of model structure on flux retrievals, three different retrieval schemes are compared. The schemes include a traditional single-source Penman–Monteith model (Monteith, 1965), a two-layer model based on Shuttleworth and Wallace (1985) and a three-source model based on Mu et al. (2011). To assess the impact of parameterization choice on model performance, a number of commonly used formulations for aerodynamic and surface resistances were substituted into the different formulations. Model response to these changes was evaluated against data from twenty globally distributed FLUXNET towers, representing a cross-section of biomes that include grassland, cropland, shrubland, evergreen needleleaf forest and deciduous broadleaf forest. Scenarios based on 14 different combinations of model structure and parameterization were ranked based on their mean value of Nash–Sutcliffe Efficiency. Results illustrated considerable variability in model performance both within and between biome types. Indeed, no single model consistently outperformed any other when considered across all biomes. For instance, in grassland and shrubland sites, the single-source Penman–Monteith model performed the best. In croplands it was the three-source Mu model, while for evergreen needleleaf and deciduous broadleaf forests, the Shuttleworth–Wallace model rated highest. Interestingly, these top ranked scenarios all shared the simple lookup-table based surface resistance parameterization of Mu et al. (2011), while a more complex Jarvis multiplicative method for surface resistance produced lower ranked simulations. The highly ranked scenarios mostly employed a version of the Thom (1975) formulation for aerodynamic resistance that incorporated dynamic values of roughness parameters. This was true for all cases except over deciduous broadleaf sites, where the simpler aerodynamic resistance approach of Mu et