Configuration of L-band Polarimetric Signatures and Scattering Mechanisms of Forest Targets in the Brazilian Amazon

The objective of this study is to analyze the graphic representation of polarimetric signatures of airborne SAR-R99B data (L-band) in primary forest, secondary successions, forest with timber exploitation and those under recovery after a surface burning process. Additionally, another objective is an exploratory analysis of scattering mechanisms of forest typology in accordance with the alternative procedure of SAR image classification based on target decomposition. The area under study is located at the Tapajós region (Brazil). At the representation of polarimetric signatures, the normalized cross-section of the forest target (σ) was plotted on a three-dimensional graphic as a function of the orientation angle, ellipticity angle, referring to the ellipse of polarization. The resulting surfaces were visually compared and the configuration of each plot was analyzed with support of physiognomic-structural information collected during forest inventories. On the other hand, the distinction between simple and multiple scattering mechanism from the target decomposition was done by the association of entropy and alpha angle values for each sample area. Some results can be mentioned: (a) from the analysis of polarimetric signatures one can verify that the primary forest sections present a relatively high pedestal when compared to the secondary succession. (b) for all thematic classes studied the pixel distribution in the (H, α) bidimensional space was more frequent at zones 5, 4 and 6 (decreasing frequency order). This study improves the understanding of the interaction mechanisms between L-band SAR signals and structural parameters of tropical rainforest, subsidizing the inventory and the monitoring of land cover in the Amazon region.