Abstract
In recent decades, the melting of the Greenland Ice Sheet (GrIS) has become one of the major causes of global sea-level rise. Supraglacial lakes (SGLs) are typical hydrological features produced on the surface of the GrIS during the melt seasons. The existence and evolution of SGLs play an important role in the melting process of the ice sheet surface. To understand the distribution and recent changes of SGLs in Greenland, this study developed a random forest (RF) algorithm incorporating the texture and morphological features to automatically identify SGLs based on the Google Earth Engine (GEE) platform. Sentinel-2 imagery was used to map the SGLs inventory in Greenland during the 2016–2018 melt seasons and to explore the spatial and temporal variability characteristics of SGLs. Our results show changes in SGLs from 2016 to 2018, with the total area decreasing by ~1152.22 km2 and the number increasing by 1134; SGLs are mainly distributed in western Greenland (SW, CW, NW) and northeastern Greenland (NE), where the NE region has the largest number of observed SGLs and the largest SGL was with the surface area of 16.60 km2 (2016). SGLs were found to be most active in the area with the elevation of 800–1600 m and the slope of 0–5°, and showed a phenomenon of retreating to lower elevation areas and developing to steeper slope areas. Our work provided a method for rapid inventory of SGLs. This study will help monitor the mass balance of the GrIS and predict future rapid ice loss from Greenland.
Highlights
In recent decades, the Greenland Ice Sheet (GrIS) has been in a state of accelerated mass loss and has become a major contributor to global sea-level rise [1,2]
The GrIS produces a large amount of meltwater during the melt seasons, which is transported on the surface of the ice sheet by topography and other factors [4]
Since some runoffs with large amounts of water were connected with supraglacial lakes (SGLs) as an inseparable whole, they were included in the final results of SGL extraction
Summary
The Greenland Ice Sheet (GrIS) has been in a state of accelerated mass loss and has become a major contributor to global sea-level rise [1,2]. Ice sheet surface ablation becomes one of the main causes of GrIS mass loss and even global sea-level rise. The GrIS produces a large amount of meltwater during the melt seasons, which is transported on the surface of the ice sheet by topography and other factors [4]. Part of the meltwater collects in topographic depressions on the ice cap surface through surface runoff, forming supraglacial lakes (SGLs) [5]. SGLs tend to form at the same location each year due to the control of basal topography depressions of the Greenland ablation zone [6,7]
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