Spatial extent of thermokarst lagoons along pan-Arctic coasts - an upscaling approach
2023
Jenrich, Maren | Nitze, Ingmar | Laboor, Sebastian | Angelopoulos, Michael | Grosse, Guido | Strauss, Jens
Along the ice rich pan-Arctic permafrost coasts thermokarst lagoons are a common landscape feature. These lagoons form when thermokarst lakes are inundated permanently or intermittently by the sea. This is the first estimation of the area of pan-Arctic thermokarst lagoons based on the mapping of 79 lagoons in 5 representative arctic regions: Mackenzie Delta (CA), Theshekpuk Lake coast (USA), Baldwin Peninsula (USA), Tiksi coast (RU), Lena Delta (RU). The extent of each of the lagoons was determined using the Global Surface Water dataset which is based on Landsat-5, -7, and -8 satellite images from 1984 to 2018 at 30m resolution (Pekel et al., 2016). Water bodies were defined by a water occurrence threshold of >75% over this time period. The raster dataset was vectorized and smaller geometric errors, which occurred during vectorization, were solved with the Fix Geometry function in QGIS3.6. The lagoon polygons were selected manually and these water bodies were split from the ocean by using the function “split by line”. The calculation of the polygon area is based on the re-projection in EPSG:32608, EPSG:26905, EPSG:32604, EPSG:32652 for Mackenzie Delta, Teshekpuk Lake coast, Baldwin Peninsula, Tiksi and Lena Delta coast respectively. The lagoon selection is based on the published dataset https://doi.org/10.1594/PANGAEA.934158. The dataset consists of a polygon shape file for the 79 extracted thermokarst lagoons, a point shape file with coordinates for all lagoons and a data sheet.
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