Study of Thermokarst Lake Size Distribution in the Eastern Part of the Russian Arctic Based on Combining Sentinel-2 and Kanopus-V Images

The article is devoted to the issues of remote studies of the size distribution of thermokarst lakes in the territory of the eastern part of the Russian Arctic. The studies were carried out in the Arctic territories of the Northeastern (Yakutia) and Chukotka tundras, which represent relatively homogeneous areas in terms of their natural properties, referred to here as ecoregions. Remote studies of the distribution of thermokarst lakes by area were conducted using satellite images from the Kanopus-B and Sentinel-2 (with spatial resolution of 2.1 and 20 m, respectively), obtained in the summer months of 2017–2021. The lakes were interpreted using Sentinel-2 satellite image mosaic, which provides full coverage of the study territories, Kanopus-B images at 12 test sites, and QGIS 3.22 tools. We briefly described the method of integration (combination) of data from Kanopus-B and Sentinel-2 images for plotting synthesized histograms of lakes distribution by their sizes. The technique allowed us to get histograms of lake distribution in a very wide range of their sizes from 50 to 10⁸ m² in the studied Arctic ecoregions. The histogram plots show a similar behavior in both ecoregions, manifesting itself in an increase in the number of lakes as their size decreases. It is shown that the main contribution to the number of lakes in the Northeastern tundra is made by much larger lakes than in the Chukchi tundra, which may indicate a significant difference in the geocryological conditions in different Arctic territories of the eastern part of the Russian Arctic. The degree of the lakeing of the territories was assessed. It was shown that the lakeing of the Northeastern tundra is 7 times higher than in the studied territories of Chukotka.