| Summary: | Thermokarst lagoons develop in permafrost lowlands along the ice-rich Arctic coast when thermokarst lakes or basins with bottom elevations at or below sea level are breached by the sea due to erosion, sea-level rise, or connection via drainage channels. Thermokarst lagoons, as dynamic landforms at the interface of terrestrial permafrost and marine systems, play a crucial role in the transformation of permafrost carbon under rising marine influence. Here we present a comprehensive dataset consisting of the first manual thermokarst lagoon area mapping, a more precise number of thermokarst lagoons and a detailed lagoon classification for thermokarst lagoons along the pan-Arctic coast from Taymyr Peninsula in Russia to the Tuktoyaktuk Peninsula in Canada. This is an updated dataset based on the previous work of Jenrich et al. 2021 and Jenrich et al. 2023. The main improvements include (1) counting thermokarst lagoons individually within a lagoon system, as long as the distinct round form of former lake basins is visible; (2) manually calculating the area for all mapped thermokarst lagoons based on the updated Global Surface Water Dataset from 1984-2021 by Pekel et al., 2016; and (3) classifying lagoons based on connectivity to the sea into 5 connectivity classes. We identified 520 thermokarst lagoons covering an area of 3457 km2. Methods: Pan-Arctic thermokarst lagoon distribution and area were mapped using QGIS version 3.34 and Google Earth Engine. The updated Global Surface Water Dataset by Pekel et al., 2016, based on Landsat-5, -7, and -8 satellite images from 1984-2021, was used to create masks with a threshold of >75% based on water occurrence, which enabled the manual splitting of polygons from the resulting mask vector data and extraction of thermokarst lagoon areas. Mapping and area extraction also relied on Sentinel-2 imagery from 2023/07/01-2023/08/30, basemaps Google Satellite and ESRI Satellite, and the digital elevation model ArcticDEM and its hillshade HSarcticDEM (Porter et al., 2018). The ...
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