Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 7, 2477-2484, 2014
https://doi.org/10.5194/gmd-7-2477-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Model description paper
24 Oct 2014
Development of a semi-parametric PAR (Photosynthetically Active Radiation) partitioning model for the United States, version 1.0
J. C. Kathilankal1, T. L. O'Halloran2, A. Schmidt3, C. V. Hanson3, and B. E. Law3 1LI-COR Inc. 4647 Superior Street, Lincoln, NE 68504, USA
2Sweet Briar College, Department of Environmental Sciences, Sweet Briar, VA 24595, USA
3Department of Forest Ecosystems and Society College of Forestry, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331, USA
Abstract. A semi-parametric PAR diffuse radiation model was developed using commonly measured climatic variables from 108 site-years of data from 17 AmeriFlux sites. The model has a logistic form and improves upon previous efforts using a larger data set and physically viable climate variables as predictors, including relative humidity, clearness index, surface albedo and solar elevation angle. Model performance was evaluated by comparison with a simple cubic polynomial model developed for the PAR spectral range. The logistic model outperformed the polynomial model with an improved coefficient of determination and slope relative to measured data (logistic: R2 = 0.76; slope = 0.76; cubic: R2 = 0.73; slope = 0.72), making this the most robust PAR-partitioning model for the United States currently available.

Citation: Kathilankal, J. C., O'Halloran, T. L., Schmidt, A., Hanson, C. V., and Law, B. E.: Development of a semi-parametric PAR (Photosynthetically Active Radiation) partitioning model for the United States, version 1.0, Geosci. Model Dev., 7, 2477-2484, https://doi.org/10.5194/gmd-7-2477-2014, 2014.
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