Calibration of the water cloud model at C-Band for winter crop fields and grasslands

Étalonnage du modèle de nuages d'eau en bande C pour les champs de cultures d'hiver et les prairies

N. Baghdadi (1) , Mohammad El Hajj (1) , Mehrez Zribi (2) , Safa Bousbih

1 UMR TETIS - Territoires, Environnement, Télédétection et Information Spatiale
2 CESBIO - Centre d'études spatiales de la biosphère

In a perspective to develop an inversion approach for estimating surface soil moisture of crop fields from Sentinel-1/2 data (radar and optical sensors), the Water Cloud Model (WCM) was calibrated from C-band Synthetic Aperture Radar (SAR) data and Normalized Difference Vegetation Index (NDVI) values collected over crops fields and grasslands. The soil contribution that depends on soil moisture and surface roughness (in addition to SAR instrumental parameters) was simulated using the physical backscattering model IEM (Integral Equation Model). The vegetation descriptor used in the WCM is the NDVI because it can be directly calculated from optical images. A large dataset consisting of radar backscattered signal in VV and VH polarizations with wide range of incidence angle, soil moisture, surface roughness, and NDVI-values was used. It was collected over two agricultural study sites. Results show that the soil contribution to the total radar backscattered signal is lower in VH than in VV because VH is more sensitive to vegetation cover. Thus, the use of VH alone or in addition to VV for retrieving the soil moisture is not advantageous in presence of well-developed vegetation cover.

Mots clés: modelling; soil water content; remote sensing; calibration; prairies

Mots clés: PRAIRIE; ETALONNAGE; MODELISATION; HUMIDITE DU SOL; TELEDETECTION

Domaines: Sciences de l'environnement

N. Baghdadi, Mohammad El Hajj, Mehrez Zribi, Safa Bousbih. Calibration of the water cloud model at C-Band for winter crop fields and grasslands. Remote Sensing, 2017, 9 (969), 13 p. ⟨10.3390/rs9090969⟩. ⟨hal-01735644⟩