Evaluating the Semiempirical [Formula Omitted]- [Formula Omitted] Model Used to Calculate the L-Band Emissivity of a Rough Bare Soil

• Published in: IEEE transactions on geoscience and remote sensing Vol. 51; no. 7; p. 4075
• Main Authors: Lawrence, Heather, Wigneron, Jean-Pierre, Demontoux, Francois, Mialon, Arnaud, Kerr, Yann H
• Format: Journal Article
• Language: English
• Published: New York The Institute of Electrical and Electronics Engineers, Inc. (IEEE) 01.07.2013
• Subjects: Studies
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2012.2226995

In this paper, a numerical modeling approach was used to evaluate the semiempirical [Formula Omitted]-[Formula Omitted] model used in the Soil Moisture and Ocean Salinity (SMOS) retrieval algorithm to account for roughness effects over bare soil. The [Formula Omitted]-[Formula Omitted] model uses four parameters, [Formula Omitted], [Formula Omitted], [Formula Omitted], and [Formula Omitted], 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 [Formula Omitted] and autocorrelation length [Formula Omitted]. First, a numerical modeling approach was used to calculate rough soil emissivities for different roughness and soil moisture conditions. Second, [Formula Omitted] -[Formula Omitted] model parameters were retrieved by minimizing a cost function between these emissivities and those calculated by the [Formula Omitted]-[Formula Omitted] model. It was found that the retrieved [Formula Omitted] could be related directly to [Formula Omitted] and that [Formula Omitted], [Formula Omitted], and [Formula Omitted] were dependent on [Formula Omitted]. [Formula Omitted] was found to have a negligible dependence on soil moisture. Based on these results, a new model was proposed where the four [Formula Omitted]-[Formula Omitted] model parameters were calibrated to [Formula Omitted]. 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 [Formula Omitted], which was within the desired 0.04-[Formula Omitted] error margin for the SMOS mission.