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Title: ANALYSIS OF VEGETATION MICROWAVE PARAMETERS DEPENDENCY ON VIEW ANGLE AND POLARIZATION (SMOS MISSION)

Author
item PARDE, M. - INRA-UNITE CSE
item WIGNERON, J. - INRA-UNITE CSE
item CHANZY, A. - INRA-UNITE CSE
item Schmugge, Thomas

Submitted to: Radio Science
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The main objective of the Soil Moisture and Ocean Salinity (SMOS) mission is to deliver crucial variables of the land surfaces: soil moisture through the use of L-band (1.4GHz) microwave radiometer. The SMOS mission will make multiple measurements of the brightness temperature at many view angles and two polarizations. To model the soil first layer water content, we have to account for the effect of the vegetation on soil emission and for the vegetation emission itself. Very few studies have investigated to date the vegetation microwave signature, including the angular and the polarization dependence. Because of the SMOS measurement configuration view angle polarization and vegetation species dependence of the vegetation microwave signature, has to be studied. The model we used for simulating the vegetation emission is the tau-omega model. In this model, the single scattering albedo, omega, accounts for scattering effects and the optical depth, tau, accounts for attenuation effects within the canopy. In order t model accurately the crop micorwave signature, it is thus necessary to compute the dependence of omega and tau as a function of view angle, polarization and canopy type. To perform this study, we used the BARC (Wang et al.,1981) and PORTOS (Wigneron et al.,1995) data sets over corn, wheat, alfalfa, grass and soybean. A simple approach was used to calculate the microwave parapmeters b and omega for each crop canopy. Results showed that for corn, the angular and polarization dependence of b and omega are significant. For the alfalfa and grass canopies, this dependence is lower. Moreover, the values of b are higher for grass and alfalfa than for corn. It seems that scattering effects are low within the stem-dominate canopy (corn) that within the low and leafy grass cover.