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Numerical Simulation of the Full-Polarimetric Emissivity of Vines and Comparison with Experimental Data
Remote Sensing Laboratory, Dept. Teoria del Senyal i Comunicacions, Universitat Politècnica de Catalunya, Campus Nord - D3, Jordi Girona 1-3, E-08034 Barcelona, Spain
SMOS Barcelona Expert Centre, Pg. Marítim de la Barceloneta 37-49, E-08003, Barcelona, Spain
Dept. Physics, System Engineering and Signal Theory, University of Alicante, P.O.Box 99, E-03080 Alicante, Spain
* Author to whom correspondence should be addressed.
Received: 30 April 2009; in revised form: 2 July 2009 / Accepted: 11 July 2009 / Published: 20 July 2009
Abstract: Surface soil moisture is a key variable needed to understand and predict the climate. L-band microwave radiometry seems to be the best technique to remotely measure the soil moisture content, since the influence of other effects such as surface roughness and vegetation is comparatively small. This work describes a numerical model developed to efficiently compute the four elements of the Stokes emission vector (Th, Tv, TU and TV) of vegetation-covered soils at low microwave frequencies, as well as the single-scattering albedo and the extinction coefficient of the vegetation layer over a wide range of incidence angles. A comparison with L-band (1.400–1.427 MHz) experimental radiometric data gathered during the SMOS REFLEX 2003 field experiment over vines is presented and discussed. The measured and simulated emissivities at vertical polarization agree very well. However, at horizontal polarization there is some disagreement introduced by the soil emission model. Important radiometric parameters, such as the albedo, the attenuation and the transmissivity are computed and analyzed in terms of their values and trends, as well as their dependence on the observation and scene parameters. It is found that the vegetation attenuation is mainly driven by the presence of branches and leaves, while the albedo is mainly driven by the branches. The comparison of the simulated parameters with the values obtained by fitting the experimental data with the t-w model is very satisfactory.
Keywords: polarimetric radiometry; Stokes parameters; emission; scattering; vegetation; vines; L-systems; soil moisture
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Martinez-Vazquez, A.; Camps, A.; Lopez-Sanchez, J.M.; Vall-llossera, M.; Monerris, A. Numerical Simulation of the Full-Polarimetric Emissivity of Vines and Comparison with Experimental Data. Remote Sens. 2009, 1, 300-317.
Martinez-Vazquez A, Camps A, Lopez-Sanchez JM, Vall-llossera M, Monerris A. Numerical Simulation of the Full-Polarimetric Emissivity of Vines and Comparison with Experimental Data. Remote Sensing. 2009; 1(3):300-317.
Martinez-Vazquez, Alberto; Camps, Adriano; Lopez-Sanchez, Juan Manuel; Vall-llossera, Mercedes; Monerris, Alessandra. 2009. "Numerical Simulation of the Full-Polarimetric Emissivity of Vines and Comparison with Experimental Data." Remote Sens. 1, no. 3: 300-317.