Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 9, 2195-2201, 2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Technical note
18 Jun 2012
Technical Note: Calibration and validation of geophysical observation models
M. S. Salama1,2, R. Van der Velde1, H. J. van der Woerd3, J. C. Kromkamp2, C. J. M. Philippart4, A. T. Joseph5, P. E. O'Neill5, R. H. Lang6, T. Gish7, P. J. Werdell8,9, and Z. Su1 1Department of Water Resources, ITC, University of Twente, The Netherlands
2Royal Netherlands Institute for Sea Research (NIOZ), Yerseke, The Netherlands
3Institute for Environmental Studies (IVM), VU University, The Netherlands
4Royal Netherlands Institute for Sea Research (NIOZ), The Netherlands
5Hydrological Sciences Branch/614.3, Hydrospheric and Biospheric Sciences Laboratory, NASA/GSFC, USA
6Dept. of Electrical and Computer Engineering, George Washington University, USA
7Hydrology and Remote Sensing Lab, USDA-ARS, USA
8NASA Goddard Space Flight Center, Ocean Ecology Branch Code 614.2, USA
9Science Systems and Applications, Inc., Lanham, USA
Abstract. We present a method to calibrate and validate observational models that interrelate remotely sensed energy fluxes to geophysical variables of land and water surfaces. Coincident sets of remote sensing observation of visible and microwave radiations and geophysical data are assembled and subdivided into calibration (Cal) and validation (Val) data sets. Each Cal/Val pair is used to derive the coefficients (from the Cal set) and the accuracy (from the Val set) of the observation model. Combining the results from all Cal/Val pairs provides probability distributions of the model coefficients and model errors. The method is generic and demonstrated using comprehensive matchup sets from two very different disciplines: soil moisture and water quality. The results demonstrate that the method provides robust model coefficients and quantitative measure of the model uncertainty. This approach can be adopted for the calibration/validation of satellite products of land and water surfaces, and the resulting uncertainty can be used as input to data assimilation schemes.

Citation: Salama, M. S., Van der Velde, R., van der Woerd, H. J., Kromkamp, J. C., Philippart, C. J. M., Joseph, A. T., O'Neill, P. E., Lang, R. H., Gish, T., Werdell, P. J., and Su, Z.: Technical Note: Calibration and validation of geophysical observation models, Biogeosciences, 9, 2195-2201,, 2012.
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