%0 Book Section
%9 OS CH : Chapitres d'ouvrages scientifiques
%A Magagi, R.D.
%A Kerr, Y.H.
%T Vegetation cover study over arid semi-arid areas : use of ERS1 wind scatterometer
%B Interactions surface continentale/atmosphère : l'expérience HAPEX-Sahel
%C Paris
%D 1996
%E Hoepffner, Michel
%E Lebel, Thierry
%E Monteny, Bruno
%L fdi:010008381
%G ENG
%I ORSTOM
%@ 2-7099-1307-0
%K COUVERT VEGETAL ; HUMIDITE DU SOL ; RADIOMETRIE ; TELEDETECTION SPATIALE ; SATELLITE ERS1 ; SIMULATION ; VARIATION TEMPORELLE
%K ZONE ARIDE ; ZONE SEMIARIDE ; NIGER
%K NIAMEY REGION ; BANIZOUMBOU REGION
%P 619-634
%U https://www.documentation.ird.fr/hor/fdi:010008381
%> https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_6/colloques2/010008381.pdf
%W Horizon (IRD)
%X The ERS-1 wind scatterometer (5.3 Ghz) operates in VV polarization with a resolution of 50 km. For a particular target, it measures three backscattering coefficients from its 3 antennas. The aim of this study is to use the information delivered by the wind scatterometer over land surfaces in arid and semi-arid environments to infer soil moisture. The rationale of the approach presented is that, if we assume that the soil/vegetation interaction term can be ignored, the signal is the sum of soil and vegetation contributions. The soil contribution is driven by the soil's dielectric properties and surface roughness. In the presence of vegetation, this contribution is attenuated by a factor which depends on canopy characteristics (water content, shape, height, density) and radiometer viewing characteristics. To assess and monitor soil moisture, a knowledge of the vegetation characteristics is thus required. In order to quantify the influence of vegetation on the signal, we will use a semi-empirical model (first order radiative transfer model), extract canopy optical thickness (tau) and simple scattering albedo using the angle dependence. The different contributions of the signal will be compared within different angular ranges. The semi-empirical model will be applied at low incidence angles to retrieve soil moisture. (Résumé d'auteur)
%S Colloques et Séminaires
%B Journées Hydrologiques
%8 1994/09/13-14
%$ 062MECEAU02 ; 126TELAPP04