Browsing by Author "Geldsetzer, Torsten"
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Item Open Access Firn Characterization of the Accumulation Zone of Kaskawulsh Glacier, Yukon Territory, Canada(2019-05-03) Ochwat, Naomi; Marshall, Shawn; Moorman, Brian J.; Geldsetzer, Torsten; Shugar, Dan H.While glacier mass balance studies allow investigation of the changing cryosphere, large ice sheets and remote, glaciated regions often lack the potential for detailed field studies. Remote sensing techniques are applied in mass balance studies, however, these methods are challenged because of their assumptions on density. In spring 2018, I extracted two firn cores (21 m and 36 m) from the accumulation zone of Kaskawulsh Glacier, St. Elias Mountains, Yukon and analyzed refrozen ice layers, snow densification processes, and isotopic and ionic signals. Meltwater percolation and refreezing events are evident in the cores through the quantity of ice layers, the presence of a perennial firn aquifer, and the altered isotope and glaciochemical signatures. These processes resulted in surface lowering of 10 cm/yr and washed out most of the isotope and ion seasonal signal. My study advances understanding in the dynamics of a changing accumulation zone in the St. Elias Icefields.Item Open Access Pre- and Post-Disaster Remote Sensing with Drones for Supporting Disaster Management(2023-04-27) Kucharczyk, Maja; Hugenholtz, Chris H.; Geldsetzer, Torsten; Hay, Geoffrey J.; Moorman, Lynn; Slick, JeanSmall (< 25 kg) aerial drones have expanded the remote sensing toolkit for disaster management activities, resulting in hundreds of published case studies in the past two decades. The overall goal of this doctoral research, which comprises three related studies, is to evaluate drone-based pre- and post-disaster remote sensing as a tool to support disaster management. The first study provides a critical review of drone-based remote sensing in natural hazard-related disasters to highlight research trends, biases, and expose new opportunities. Recommendations for future research include a greater focus on demonstrating and evaluating drone-based support of pre-disaster data acquisition (a preparedness activity) and rapid damage assessment (a response activity). As such, the second study presents the first pre-disaster drone-based mapping mission over an urban area (downtown Victoria, British Columbia) approved by Transport Canada. The objective was to assess the quality of 3D data obtained with the only legally approved drone. Finally, the third study demonstrates rapid mapping of hurricane roof damage using artificial intelligence (deep learning) and drone imagery, including an accuracy assessment. Overall, this doctoral research identified critical knowledge gaps in the field of pre- and post-disaster remote sensing with small aerial drones, and then demonstrated and evaluated drone-based support of two building-damage-related activities that were recommended for future research.Item Open Access The dielectric and polarimetric microwave scattering properties of snow covered sea ice(2009) Geldsetzer, Torsten; Yackel, JohnIn this thesis I investigate the dielectric and polarimetric microwave scattering properties of snow-covered sea ice. I present the first measurements of the dielectric constant and the dielectric loss for brine-wetted snow on first-year sea ice. Using these measurements, I develop empirical and semi-physical models that relate brine volume fraction and brine saturation in the snow to the dielectric properties at MHz and GHz frequencies. To investigate the polarimetric scattering properties of snow-covered sea ice, I describe the field deployment and signal processing methods for a new surface-based C-band scatterometer. Using observations of in situ microwave scattering signatures, geophysical properties and associated dielectric properties of brine-wetted snow, I describe, model and theorize on the polarimetric microwave scattering properties of snow-covered sea ice. I extend this knowledge of dielectric and scattering properties to regional-scale multipolarized SAR investigations for enhancing the discrimination of sea ice types and open water.