10.1594/PANGAEA.968886Jenrich, MarenMarenJenrich0000-0002-1330-7461Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, PotsdamUniversity of PotsdamProdinger, MariaMariaProdingerAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, PotsdamUniversität HamburgNitze, IngmarIngmarNitze0000-0002-1165-6852Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, PotsdamGrosse, GuidoGuidoGrosse0000-0001-5895-2141Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, PotsdamUniversity of PotsdamStrauss, JensJensStrauss0000-0003-4678-4982Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, PotsdamPANGAEA2024Classificationconnectivitylagoon sizePermafrost coastsshapefileThermokarst LagoonFile contentBinary ObjectBinary Object (File Size)CommentSatellite imageryCarbon in Permafrost / Kohlenstoff im Permafrost (KoPF)Changing Arctic Carbon cycle in the cOastal Ocean Near-shore (CACOON)Rapid Permafrost Thaw in a Warming Arctic and Impacts on the Soil Organic Carbon Pool (PETA-CARB)1984-01-01T00:00:00/2021-12-31T00:00:00Dataset10.1594/PANGAEA.93415810.1594/PANGAEA.94826710.1038/nature2058410.7910/DVN/OHHUKH9 data pointstext/tab-separated-valuesCreative Commons Attribution 4.0 InternationalThermokarst 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 thermokarst lagoon classification employed a geomorphological approach based on Sentinel-2 imagery and basemaps Google Satellite and ESRI Satellite. Connectivity classes were visually defined and attributed to thermokarst lagoons based on: 1) the size of the lagoon opening relative to its overall size, 2) whether it was directly connected or subsequent within a lagoon system, and 3) interactivity within the lagoon system.

The five classes range from 5 - very high connectivity to 1 - very low connectivity:
5 - Lagoon, always open (Lao) - Very high connectivity - Lagoon in direct exchange with the sea.
4 - Lagoon, mostly open (Lmo) - High connectivity - Barrier islands or sand spits only slightly block exchange with the sea or subsequent lagoon which is very well connected to the primary lagoon.
3 - Lagoon, semi-open (Lso) - Medium connectivity - Exchange limited either temporally or spatially due to barrier islands and sand spits or subsequent lagoon which is well connected to the primary lagoon.
2 - Lagoon, limited open (Llo) - Low connectivity - Exchange very limited due to very small opening or narrow channel or subsequent lagoon which is less connected to primary lagoon due to small channel or high distance.
1 - Lagoon, nearly-closed (Lnc) - Very low connectivity - Exchange strongly limited due to long and narrow channel, or subsequent lagoon with very limited exchange. Temporary lake characteristics are possible.-134.493126.30469.46973.408Federal Ministry of Education and Researchhttps://doi.org/10.13039/50110000234703F0764BVerbundprojekt: WTZ Russland - KoPf; Kohlenstoffumsatz und Treibhausgasfreisetzung aus tauendem Permafrost Nordostsibiriens unter sich ändernden Umwelt- und KlimabedingungenFederal Ministry of Education and Researchhttps://doi.org/10.13039/50110000234703F0764FVerbundprojekt: WTZ Russland - KoPf; Kohlenstoffumsatz und Treibhausgasfreisetzung aus tauendem Permafrost Nordostsibiriens unter sich ändernden Umwelt- und KlimabedingungenFederal Ministry of Education and Researchhttps://doi.org/10.13039/50110000234703F0806AWTZ Großbritannien: CACOON - Veränderung des arktischen Kohlenstoffkreislaufs im küstennahen OzeanNatural Environment Research Councilhttps://doi.org/10.13039/501100000270NE/R012806/1Changing Arctic Carbon cycle in the cOastal Ocean Near-shoreSeventh Framework Programme of the European Commissionhttps://doi.org/10.13039/100011102338335Rapid Permafrost Thaw in a Warming Arctic and Impacts on the Soil Organic Carbon Pool