An inventory of supraglacial lakes and channels across the West Antarctic Ice Sheet

[摘要] Quantifying the extent and distribution of supraglacial hydrology, i.e. lakesand streams, is important for understanding the mass balance of the Antarcticice sheet and its consequent contribution to global sea-level rise. Theexistence of meltwater on the ice surface has the potential to affect iceshelf stability and grounded ice flow through hydrofracturing and theassociated delivery of meltwater to the bed. In this study, we systematicallymap all observable supraglacial lakes and streams in West Antarctica byapplying a semi-automated Dual-NDWI (normalised difference water index)approach to >2000 images acquired by the Sentinel-2 and Landsat-8satellites during January 2017. We use a K-means clustering method topartition water into lakes and streams, which is important for understandingthe dynamics and inter-connectivity of the hydrological system. When comparedto a manually delineated reference dataset on three Antarctic test sites, ourapproach achieves average values for sensitivity (85.3  % and77.6  % ), specificity (99.1  % and 99.7  % ) andaccuracy (98.7  % and 98.3  % ) for Sentinel-2 and Landsat-8acquisitions, respectively. We identified 10 478 supraglacial features(10 223 lakes and 255 channels) on the West Antarctic Ice Sheet (WAIS) andAntarctic Peninsula (AP), with a combined area of 119.4  km 2 (114.7  km 2 lakes, 4.7  km 2 channels). We found27.3  % of feature area on grounded ice and 54.9  % onfloating ice shelves. In total, 17.8  % of feature area crossed thegrounding line. A recent expansion in satellite data provision made newcontinental-scale inventories such as these, the first produced for WAIS andAP, possible. The inventories provide a baseline for future studies and abenchmark to monitor the development of Antarctica's surface hydrology in awarming world and thus enhance our capability to predict the collapse of iceshelves in the future. The dataset is available at https://doi.org/10.5281/zenodo.5642755 ( Corr et al. ,  2021 ) .

[学科分类] 眼科学