Abstract: Blue ice, a special surface feature of Antarctica, plays an important role in affecting the energy balance at regional to continental scales owing to its low albedo. Its surface ablation leads to the exposure of old ice, making the blue ice an ideal site for paleoclimate study. In addition, blue ice areas are the preferred landing areas for aircrafts because of its high density and hardness. In this study, we propose a rapid, effective, and automatic blue ice extraction method based on a combined index. Using Landsat-8 imagery, we combined the blue ice index and shadow index to derive the Antarctic blue ice distribution. These updated Antarctic blue ice data provide a new resource for studying the Antarctic surface energy balance, paleoclimatology, and selecting blue ice airport sites. We extracted the blue ice locations north of 82.5°S on the Antarctic from 940 scenes of Landsat-8 imagery between 2017 and 2019, while the blue ice locations south of 82.5°S on the Antarctic were extracted from MODIS snow particle size data from 2014. These data were used to map the blue ice distribution over the whole of Antarctica. Results showed that using Landsat-8 imagery, the average accuracy of the blue ice combined index method reached 0.87. The resulting blue ice distribution on the Antarctic is spatially consistent with previous results. The total area of Antarctic blue ice is about 1.7 ×10⁵ km², 91.4% of which occurs in East Antarctica. Blue ice areas mainly exist near exposed nunataks or mountains,as well as coastal areas. About 60.4% of the Antarctic blue ice occurs within the inland from its coastline to 200 km southward.

Key words: Antarctic, blue ice, Landsat-8, combined index method