Speaking: Helena Bergstedt b.geos, Austria
The Permafrost Discovery Gateway hosts a monthly webinar series on the second Thursday of each month at 9:00 am Alaska time, raising topics of interest to the permafrost community. The webinar aims to 1) connect the international science community interested in big data remote sensing of permafrost landscapes, and 2) provide the Permafrost Discovery Gateway development team with end-user stories (by the presenter and webinar participants), such as exploring tools the community needs to create and explore big data.
Abstract
Lakes and drained lake basins (DLB) are ubiquitous landforms in permafrost lowland regions. The long-term dynamics of lake formation and drainage is evident in the abundance of DLBs covering 50% to 75% of permafrost lowlands in parts of Alaska, Siberia, and Canada. The mosaic of vegetative and geomorphic succession within DLBs and the distinct differences between DLBs and surrounding areas can be discriminated and used to derive a landscape-scale classification employing various indices derived from multispectral remote sensing imagery that, when combined with field sampling and peat initiation timing, can be used to scale across spatial and temporal domains. Previously published local and regional studies have demonstrated the importance of DLBs regarding carbon storage, greenhouse gas and nutrient fluxes, hydrology, geomorphology, and habitat availability. A coordinated pan-Arctic scale effort is needed to map and further the understanding of DLBs in circumpolar permafrost-regions. Here we present an update of ongoing work within the International Permafrost Association (IPA) Action Group on DLBs, an effort led by the scientific community that includes developing a first pan-Arctic drained lake basin data product. A prototype of this data product covering the North Slope of Alaska published in Bergstedt et al. (2021) demonstrated the methodological basis of this large-scale mapping effort. The methodology developed here is a novel and scalable remote sensing-based approach to identifying DLBs in lowland permafrost regions. Our approach uses Landsat-8 multispectral imagery and topographic information to derive a pixel-by-pixel statistical assessment of DLB occurrence in regions with different permafrost and periglacial landscape conditions, as well as to quantify aerial coverage of DLBs. Here we present first results of a DLB dataset covering pan-Arctic permafrost lowlands. Utilizing remote sensing imagery (Landsat-8) and freely available DEM data sets (e.g., ArcticDEM, Copernicus DEM) allows us to implement our mapping approach on a circumpolar scale. Comprehensive mapping of DLBs areas across the circumpolar permafrost landscape will allow for future utilization of these data in pan-Arctic models and greatly enhance our understanding of DLBs in the context of permafrost landscapes. Better resolution of the spatial distribution of DLBs in lowland permafrost regions will improve quantitative studies on landscape diversity, wildlife habitat, permafrost, hydrology, geotechnical conditions, and high-latitude carbon cycling.