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Potentiel des nouveaux capteurs radar multi-polarisation et polarimétrique pour la caractérisation des états de surface en milieu agricole

Abstract : The objective of this thesis is to analyze information from the new radar sensor ASAR of ENVISAT and from future polarimetric sensors in the X band for the estimation of the soil roughness and soil moisture. The results obtained from the RAMSES sensor show the low potential of the radar in the X band with 30° for the discrimination of roughness classes. Nevertheless, this study showed that it is possible to identify a structural state of surface degraded because of the presence of a soil crust and to distinguish the recently tilled fields. The use of an ASAR sensor made it possible to define the optimal radar configurations for better estimating soil moisture (polarization HH at low incidences) and roughness (polarizations HH and HV at high incidences). After having observed a weak correlation between experimental measurements and those simulated by the model of retrodiffusion IEM, we applied the semi-empirical calibration of the IEM model suggested by Baghdadi et al. (2004) with an aim of better reproducing the coefficient of retrodiffusion radar over bare agricultural fields. The results obtained show that this calibration makes it possible to better retrieve the radar signal. Inversion procedures were used to estimate soil moisture from ASAR signals. The results obtained show a clear improvement in the estimation of soil moisture when two angles of incidence are used (one low and the other high). The use of data obtained in multi-polarization from an ASAR sensor does not improve the estimation of soil moisture compared to the use of only one polarization (an improvement of less than 1%).
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Submitted on : Monday, September 19, 2005 - 11:10:55 AM
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  • HAL Id : tel-00010194, version 1

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Noha Holah. Potentiel des nouveaux capteurs radar multi-polarisation et polarimétrique pour la caractérisation des états de surface en milieu agricole. Sciences de la Terre. Université d'Orléans, 2005. Français. ⟨tel-00010194⟩

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