Browsing University of Alaska Fairbanks by Type "Dissertation"
Now showing items 1-3 of 3
Blood falls, Taylor Glacier, Antarctica: subglacially-sourced outflow at the surface of a cold polar glacier as recorded by time-lapse photography, seismic data, and historical observationsBlood Falls forms when iron-rich, hypersaline, subglacially-sourced brine flows from a crack in the surface of Taylor Glacier, Antarctica. If air temperatures are low enough, the brine freezes to form a fan-shaped icing deposit. In chapter two, historical observations (including photos, oral histories, written descriptions, and field sketches) are evaluated using a confidence assessment framework to compile a history of brine icing deposit presence or absence during summer field seasons between 1903-1904 and 1993-1994. Additionally, an alternative explanation for a small, localized advance of a portion of the terminus is proposed: rather than temperature-driven ice viscosity changes, rising lake level drove temporary, localized basal sliding which induced advance, thinning, and collapse of a part of the terminus previously grounded on a proglacial moraine. In chapter three, time-lapse imagery is used to document a 2014 wintertime brine release that occurred in the absence of surface melt. This suggests that meltwater-driven fracture propagation of surface crevasses downward into the glacier was not a likely factor in this brine release event, as has been previously proposed. Further, there is no evidence for an increase in Rayleigh-wave activity prior to or during the brine release that would be characteristic of shallow seismic sources. Together, this suggests that sufficient pressure is built in the subglacial system to trigger basal crevassing and fracture propagation upward to allow brine release at the surface. In chapter four, two different seismic detectors that use ratios of short-term to long-term seismic energy variance to identify seismic events are compared. The detectors use different statistical distributions to determine what constitutes a large enough ratio to trigger an event detection. Differences between what the two detectors identify as events rather than background noise are interpreted as environmental microseismicity with a distinct diurnal and seasonal occurrence. Minimum detectable event sizes over 3-day time windows are compared. Together, these studies provide context for the history of brine release events, wintertime brine release characteristics, and descriptions of the local seismic environment at Taylor Glacier.
Critical issues in the preparation of Alaska Native teachers : perspectives of cross-cultural education development (X-CED) program graduatesThis study draws upon the experiences of 35 Alaska Native teachers who have succeeded in earning a teaching certificate through the Cross-Cultural Education Development (X-CED) Program to identify issues that affect the preparation of Native teachers for schools in rural Alaska. The guiding question of the study is: What do Native teacher eduation graduates perceive to be the factors that contributed most to their success in a field-based teacher preparation program and as teachers? Components of the question include: Why did Native students pursue a teaching credential? How did the XCED graduates go about achieving their goals? And, how do they perceive their experiences as teachers? It is evident from this study that Alaska Native people face many critical issues in their pursuit of a Bachelors degree and a teaching certificate to teach in their communities. Factors that contribute to the success of the Native teachers interviewed in this study include field-based instructors; locally driven curriculum; and school district, community, family and fellow student support. Implications for future success of Native teacher preparation efforts conclude the study.
Current exposure of Yukon Flats tribal villages' residents to PM₂.₅ from natural and anthropogenic sources: establishing baselines for climate change adaptation and resilienceHow healthy is the air in the villages during the summer fire seasons? Why does Fort Yukon always seem to be colder than the surrounding villages in winter and spring? How healthy is the air we breathe in our homes and workplaces? These are but a few of the questions asked by Alaska's Eastern Interior residential village's Indigenous Tribal Governments. A tribal-owned network of aerosol monitors and meteorological stations was installed at Ts'aahudaaneekk'onh Denh, Gwichyaa Zheh, Jałgiitsik, and Danzhit Khànlaj̜j̜ in the Yukon Flats, Alaska. To assess the exposure of residents in rural communities in the Yukon Flats to particulate matter of 2.5 [micro]m or less in diameter (PM2.5), both indoor and outdoor concentration observations were carried out from spring 2017 through to August 2019. Surface-based-temperature inversions occurred under calm wind conditions due to surface radiative cooling. In May, local emissions governed air quality with worst conditions related to road and river dust. As the warm season progressed, worst air quality was due to transport of pollutants from upwind wildfires. Absorption of solar radiation in the smoke layer and upward scattering enhanced stability and fostered the persistence of the surface-based-temperature inversions. Under weak large-scale forcing mountain-valley circulations develop that are driven by the differences in insolation. During the long dark nights, surface radiative cooling occurs in the near-surface layer of the mountain slopes of the Brooks, Ogilvie and White Mountains Ranges and at the bottom of the valley. Here surface-based-temperature inversion - known as roof-top inversions - form, while the cold air drains from the slopes. A frontal wedge forms when the cold air slides over the relatively colder air in the valley. Drainage of cold air from the Brooks Range governed the circulation and cold air pooling in the valley. At the site, which is closest to the mountains, concentrations marginally changed in the presence of temperature inversions. Indoor concentrations were measured at 0.61 m in homes and at 1.52 m heights both in homes and office/commercial buildings. Air quality was better at both heights in cabins than frame homes both during times with and without surface-based-temperature inversions. During summer indoor concentrations reached unhealthy for sensitive groups to hazardous conditions for extended times that even exceeded the high outdoor concentrations. Indoor and outdoor concentrations were strongest related for office/commercial buildings, followed by frame houses and cabins. These are but a few of the answers found in this research of meteorology effects, unhealthy locations for breathing PM2.5 air outdoors and in homes.