Sensitivity of space-borne SAR data to forest parameters over sloping terrain : theory and experiment

Castel Thierry, Beaudoin André, Stach N., Stussi N., Le Toan Thuy, Durand Patrick Y.. 2001. Sensitivity of space-borne SAR data to forest parameters over sloping terrain : theory and experiment. International Journal of Remote Sensing, 22 (12) : 2351-2376.

Liste HCERES des revues (en SHS) : oui

Thème(s) HCERES des revues (en SHS) : Géographie-Aménagement-Urbanisme-Architecture

Résumé : Recently, SAR data proved to be useful for the retrieval of forest biomass. However, the effects of terrain slope must be addressed towards the generalization of biomass retrieval for varied forest and environmental conditions. To this aim, we developed experimental and theoretical approaches allowing the study of multi-frequency/multi-polarization forest backscatter of a given forest type, as a function of forest parameters and SAR local incidence angle over the relief. The experimental results showed that the sensitivity of SAR data to biomass was similar to that obtained over a flat terrain, only if the backscatter data were calibrated for slope effects. Moreover, the backscatter must also be corrected for its angular decrease, which can be removed using a simple angular model developed under assumptions of theoretical equations. The highest correlation of corrected backscatter with forest parameters related to aboveground biomass (such as stand age and bole volume) was achieved at L-HV 55° (R2 = 0.8) with results similar to those for flat terrain. Modelling results validate the semiempirical model developed to remove the angular decrease of forest backscatter, which is due to variable optical depth with terrain slope. Results also indicated that the simple angular model may encounter problems for forested areas with low optical depth (têta <0.5) located over extreme topographic conditions (local incidence angle <10° or >80°).

Mots-clés Agrovoc : télédétection, radar, forêt, biomasse, terre en pente, modèle mathématique

Mots-clés géographiques Agrovoc : France

Classification Agris : U30 - Méthodes de recherche
K10 - Production forestière
U10 - Informatique, mathématiques et statistiques

Auteurs et affiliations

• Castel Thierry, CIRAD-AMIS-AMAP (FRA)
• Beaudoin André, LCT (FRA)
• Stach N., LCT (FRA)
• Stussi N., LCT (FRA)
• Le Toan Thuy, CESBIO (FRA)
• Durand Patrick Y., CIRAD-FORET-DIR (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/489977/)

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