Snowmelt retrieval algorithm for the Antarctic Peninsula using SAR imageries

• Published in: Anais da Academia Brasileira de Ciências
• Main Authors: CLAUDIO W. MENDES JR, JORGE ARIGONY NETO, FERNANDO L. HILLEBRAND, MARCOS W.D. DE FREITAS, JULIANA COSTI, JEFFERSON C. SIMÕES
• Format: Article in Journal/Newspaper
• Language: English
• Published: Academia Brasileira de Ciências 2022
• Subjects: Antarctic Peninsula; Envisat ASAR; SAR imagery; snowmelt; Wet Snow Zone; Science; Q; Antarctic; Asar; The Antarctic; Antarc*
• Online Access: https://doi.org/10.1590/0001-3765202220210217; https://doaj.org/article/b5c7c3b38daa473698f426451b8f2088

Abstract The classification of Synthetic Aperture Radar (SAR) images by knowledge-based algorithms with elevation and backscatter thresholds were used in several studies to detect the Wet Snow Radar Zone (WSZ) in the Antarctic Peninsula. To identify it more accurately based on its seasonal variations, this study proposed the additional use of a threshold in synthetic images, created by rationing summer and winter sigma linear images. In our algorithm we used the following thresholds to detect the WSZ in Envisat ASAR imageries, using the Radarsat Antarctic Map Digital Elevation Model as ancillary data: i) -25 dB < s0 < -14 dB; ii) slinear summer / slinear winter < 0.4; iii) elevation H < 1,200 m for northern tip and H < 800 m for southern tip of the Antarctic Peninsula. The classified images were post-processed by a focal majority 5 x 5 filter and superimposed by an image of rock outcrops derived from the Antarctic Digital Database. The ratio image threshold allowed discriminating the WSZ from the Dry Snow Radar Zone and radar shadows, as well as transitional areas between this glacier zone and the Frozen Percolation Radar Zone, which would be classified incorrectly if we used only elevation and backscatter thresholds.