Lawrence H., Wigneron J. P., Demontoux F., Mialon A., Kerr Yann. (2013). Evaluating the semiempirical H-Q model used to calculate the L-band emissivity of a rough bare soil. IEEE Transactions on Geoscience and Remote Sensing, 51 (7), p. 4075-4084. ISSN 0196-2892.
Titre du document
Evaluating the semiempirical H-Q model used to calculate the L-band emissivity of a rough bare soil
Lawrence H., Wigneron J. P., Demontoux F., Mialon A., Kerr Yann
Source
IEEE Transactions on Geoscience and Remote Sensing, 2013,
51 (7), p. 4075-4084 ISSN 0196-2892
In this paper, a numerical modeling approach was used to evaluate the semiempirical H-Q model used in the Soil Moisture and Ocean Salinity (SMOS) retrieval algorithm to account for roughness effects over bare soil. The H-Q model uses four parameters, H-R, Q(R), N-RH, and N-RV, which are usually calibrated at the ground scale for different surface types. The aim of this paper is to investigate whether these empirical parameters could be linked to the physical roughness parameters of standard deviation of surface heights sigma and autocorrelation length L-c. First, a numerical modeling approach was used to calculate rough soil emissivities for different roughness and soil moisture conditions. Second, H-Q model parameters were retrieved by minimizing a cost function between these emissivities and those calculated by the H-Q model. It was found that the retrieved H-R could be related directly to Zs = sigma(2)/L-c and that Q(R), N-RV, and N-RH were dependent on H-R. H-R was found to have a negligible dependence on soil moisture. Based on these results, a new model was proposed where the four H-Q model parameters were calibrated to Zs. This model was tested on the PORTOS 1993 data set and found to yield a root-mean-square difference between the retrieved and measured soil moisture values of similar to 0.03 m(3)/m(3), which was within the desired 0.04-m(3)/m(3) error margin for the SMOS mission.
