Remote sensing of recent changes in permafrost-influenced wetlands

• Main Author: Young, Tun Jan
• Format: Master Thesis
• Language: English
• Published: University of Cambridge 2013
• Subjects: remote sensing; permafrost; Canada; GIS; thermokarst; Arctic; Northwest Territories; Tuktoyaktuk; Tuktoyaktuk Peninsula; Thermokarst
• Online Access: https://www.repository.cam.ac.uk/handle/1810/309585; https://doi.org/10.17863/CAM.56679

Changes in thermokarst lakes have been identified across many high-latitude ecosystems at different spatial and temporal scales. With the declassification of the Landsat archive in 2008, it is now possible to conduct a near-complete yearly time series of homogenous geospatial imagery to assess the trends seen in thermokarst lake surface area. By implementing an automated land- cover classification algorithm, this study examined the dynamics of lake surface area over different spatial and temporal scales in the Tuktoyaktuk Peninsula, Northwest Territories, Canada. Due to the presence of a statistically significant structural temporal break between the years 1997 and 1998, lake areal trends were estimated at two temporal scales, a longer term scale (1985 to 2011) and its component shorter scales (1985 to 1997 and 1998 to 2011). Large lakes saw the greatest changes both in lake areal increase and decreases at all temporal scales, and was suggested to drive the overall changes in surface area. In addition, regional differences were observed in the spatial distribution of individual lake area trends. On the broad scale, a latitudinal divide bifurcated the peninsula into two regions of approximately equal area, where the northern region exhibited general trends of lake areal decline, while the southern region exhibited general trends of lake areal increase. Within these regions, meso- and local hot and cold spots were identified, some that exhibited trends in concordance with local surroundings, while others represented local spatial heterogeneity in areal trends. The spatiotemporal trends in lake area were suggested to be influenced at varying scales by atmospheric and climate variables, and by ground characteristics such as coincident permafrost and surficial geology. As the Arctic continues to warm, a continued observation of thermokarst lake evolution over both broad landscapes and localised regions will be increasingly valuable to future studies that investigate the resulting transformation of the Arctic ...