Date of Award

Summer 8-22-2025

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Quaternary and Climate Studies

First Committee Advisor

Seth Campbell

Second Committee Member

Alice Bernosky

Third Committee Member

Mike Cloutier

Abstract

Changes to glaciers and ice volume have significant downstream impacts, both ecologically and to human resources. Ice mass loss from glaciers within the Alaska region has been among the largest single contributors to SLR globally. Alaska accounts for about 25% of total global ice mass loss, and projections state that Alaskan glaciers will be responsible for 10% of all global SLR between 2030 and 2060 (Hugonnet and others, 2021). To understand the remaining volumes of glacial ice present, and to correctly predict the effect on SLR and other downstream impacts, it is necessary to take stock of ice volumes of key glaciers with the greatest amount of possible accuracy. Ground-penetrating radar (GPR) has been used for decades to study the ice thicknesses and associated volume of glaciers. However, not all glaciers are accessible for GPR surveys due to a variety of factors, such as cost, the remote nature of glaciated terrain, glacier extent, and total number of glaciers that exist globally. Therefore, scientists also rely on other techniques such as remote sensing and numerical modeling to estimate glacier ice thicknesses and volumes in the absence of significant in-situ data. Modeling has provided ice thickness and volume estimates but, in-situ measurements are necessary to calibrate or validate model results. In this thesis, I process and analyze ice thickness data derived from GPR measurements in order to determine the ice volumes of glaciers across two study sites in Alaska, 1) Jarvis Glacier in the Eastern Alaska Range and 2) the Juneau Icefield (JIF) in southeast Alaska. I compare these datasets to ice thickness estimates from the composite conservation of mass model developed by Farinotti and others (Farinotti and others, 2019). On Jarvis Glacier, the model underestimates the measured ice thicknesses by 19.869% on Jarvis Glacier, 67.233% on Echo Glacier, and 51.829% on Demorest Glacier. The Randolph Glacier Inventory (RGI) provides a consensus for the outlines of over 200,000 individual glaciers worldwide, including 86,709 in the Alaska region alone. The model used in this thesis uses these polygons derived from RGI, version 6 (RGI, 2017) as a bound for modeling each glacier, instituting a depth of 0 m ice at all RGI boundaries. I analyze the impact of these glacier boundaries on the model. I identify two types of RGI boundary that introduces error on glaciers on an icefield: 1) a medial boundary, in which the RGI boundary bisects an apparent singular glacier, and 2) a minor ice divide, in which ice masses clearly diverge at this point but do not equal 0 m depth at the boundary. Both types of boundary have been shown to introduce error on my JIF study sites, Demorest Glacier and Echo Glacier. This boundary issue has been rectified in the development of RGI outlines of larger glacier complexes, such as icefields, in RGI version 7 (RGI, 2023), but has not yet been updated in the model.

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