Scattering Characteristics of X-, C- and L-Band PolSAR Data Examined for the Tundra Environment of the Tuktoyaktuk Peninsula, Canada

Abstract

Abstract:In this study, polarimetric Synthetic Aperture Radar (PolSAR) data at X-, C-and L-Bands, acquired by the satellites: TerraSAR-X (2011), Radarsat-2 (2011), ALOS (2010) and ALOS-2 (2016), were used to characterize the tundra land cover of a test site located close to the town of Tuktoyaktuk, NWT, Canada. Using available in situ ground data collected in 2010 and 2012, we investigate PolSAR scattering characteristics of common tundra land cover classes at X-, C-and L-Bands. Several decomposition features of quad-, co-, and cross-polarized data were compared, the correlation between them was investigated, and the class separability offered by their different feature spaces was analyzed. Certain PolSAR features at each wavelength were sensitive to the land cover and exhibited distinct scattering characteristics. Use of shorter wavelength imagery (X and C) was beneficial for the characterization of wetland and tundra vegetation, while L-Band data highlighted differences of the bare ground classes better. The Kennaugh Matrix decomposition applied in this study provided a unified framework to store, process, and analyze all data consistently, and the matrix offered a favorable feature space for class separation. Of all elements of the quad-polarized Kennaugh Matrix, the intensity based elements K0, K1, K2, K3 and K4 were found to be most valuable for class discrimination. These elements contributed to better class separation as indicated by an increase of the separability metrics squared Jefferys Matusita Distance and Transformed Divergence. The increase in separability was up to 57% for Radarsat-2 and up to 18% for ALOS-2 data.

Monitoring Inter- and Intra-Seasonal Dynamics of Rapidly Degrading Ice-Rich Permafrost Riverbanks in the Lena Delta with TerraSAR-X Time Series

“…Fresh vegetation canopy can increase the fraction of volume scattering and positively affect backscatter intensity [27]. Existing studies on the effect of tundra vegetation on backscatter [23,32,56] do not address the effect of fresh vegetation on previously degraded tundra surfaces. The mixed signals of vegetated and eroding surfaces within the cliff AOIs could explain the higher standard deviations of backscatter in 2015.…”

“…Investigations from Widhalm et al [24], Antonova et al [27] and Ullmann et al [32] on X-Band SAR data in tundra landscapes showed low spatial variability in X-Band backscatter for different tundra types (polygonal wet tundra and shrub tundra) during the snow free summer months. In contrast, bare ground conditions that occur after erosion and are accompanied by the removal of the vegetation layer have been shown to have higher backscatter in X-Band with HH polarization [32].…”

“…In contrast, bare ground conditions that occur after erosion and are accompanied by the removal of the vegetation layer have been shown to have higher backscatter in X-Band with HH polarization [32]. The stability of the tundra backscatter and the high backscatter of bare ground allows for differentiation of these two surfaces.…”

Assessing Single-Polarization and Dual-Polarization TerraSAR-X Data for Surface Water Monitoring

“…An additional valuable parameter for water classification would be water levels, which have successfully been determined from wetland in SAR [40]. Multi-frequency acquisitions from different satellites, in combination with Kennaugh element decomposition, has also shown great potential for discriminating different vegetation types (e.g., [41]).…”

Special Issue on Polarimetric SAR Techniques and Applications

“…O. Yuzugullu, E. Erten, and I. Hajnsek developed in a study [5] on the estimation of biophysical variables in rice fields by employing X-band copolar data and electromagnetic modeling of the scene. Also related to vegetation, but with a broader environmental scope, the paper coauthored by T. Ullmann, S. N. Banks, A. Schmitt, and T. Jagdhuber [6] describes the response of a large number of polarimetric observables, obtained at L-, C-, and X-bands in a tundra scene located in Canada. The use of shorter wavelength imagery (X and C) was beneficial for the characterization of wetland and tundra vegetation, while L-band data highlighted differences between the bare ground classes better.…”