| Summary: | Dissertation (Ph.D.) University of Alaska Fairbanks, 2016 Lakes are abundant in high northern latitude permafrost regions. They are important ecosystem components forming a complex and dynamic landscape with repeated cycles of lake formation and drainage affecting regional hydrological and terrestrial characteristics, biogeochemical processes and carbon cycling, wildlife habitats, and human communities living in the permafrost region. Remote sensing is a useful tool to map the spatial distribution of lakes and assess its change, understand lake dynamics, and to extract useful information to study their associated feedbacks in a changing climate. In this dissertation, I focused on remote sensing studies associated with (1) methane ebullition from a thermokarst lake, (2) post-drainage succession patterns in drained thermokarst lake basins, and (3) lake change dynamics. I developed a semi-automatic classification method based on an Object-based Image Analysis (OBIA) framework to detect methane ebullition bubbles trapped in a snow-free ice-covered lake using high-resolution airborne images of Goldstream lake, Fairbanks, Alaska acquired following freeze up in October of 2011 and 2012. This study showed that remote sensing is a valuable tool to map ebullition bubbles (bubble patches) on the entire lake surface with an accuracy of > 95%, a task that is difficult to achieve through field-based survey alone. The image analysis performed by combining the mapping results from the OBIA and field-based observations showed a relationship between bubble patch brightness and ground-measured methane flux, which was then used to estimate the whole-lake methane flux. A strong inverse exponential relationship (R2 >= 0.79) was found between the percent of the surface area of lake ice covered with bubble patches and distance from the active thermokarst lake margin, indicating high methane production as a response to thermokarst activity that released labile organic-rich carbon along the eroding lake margin. Despite the ...
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