Antarctic Blue Ice Classification Using Sentinel-1/2: An Application in the Lambert Glacier Basin

The Antarctic blue ice can be classified into wind- and melt-induced based on their origins. They play a different role in the development of surface water systems, the surface energy balance, and the infrastructure. Currently, visible light remote sensing is the most effective method for mapping blue ice. However, optical imagery faces difficulties in classifying blue ice accurately, and it is also greatly influenced by weather conditions. Synthetic aperture radar (SAR) images have the potential to map blue ice under all weather conditions, but it is difficult to distinguish blue ice from other similar weak microwave reflecting surfaces. In this study, by employing a segmentation method based on band ratios of the Sentinel-2 images, we delineated the geographical distribution of blue ice area (BIA) in the Lambert Glacier Basin (LGB). Taking advantage of the disparity in coherence levels between melt- and wind-induced blue ice, we performed blue ice classification in the LGB using Sentinel-1 images. The proposed method achieves an overall accuracy of 0.91 and F1-score of 0.91 and provides blue ice types with a spatial resolution of 10 m. The total area of blue ice in the Lambert Basin was estimated to be approximately 1.986 x 10(4) km(2). Among them, the area of melt-induced blue ice was approximately 1.276 x 10(4) km(2), while the wind-induced blue ice covered around 0.710 x 10(4) km(2). Melt-induced BIA was predominantly distributed in low-altitude coastal areas and downstream of glaciers, exhibiting higher surface temperatures compared to wind-induced BIA. Wind-induced BIA, on the other hand, was mainly found near nunataks and exposed rocks, displaying higher albedo than melt-induced BIA.