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Automated Terminus Detection For Greenland's Peripheral Marine-Terminating Glaciers, Julia Liu 2020 Boise State University

Automated Terminus Detection For Greenland's Peripheral Marine-Terminating Glaciers, Julia Liu

Boise State University Theses and Dissertations

Changes in the length of marine-terminating glaciers strongly influence the mass balance of glaciers, ice caps, and ice sheets. Currently, quantification of glacier length change through measurement of terminus position relies on time-consuming and subjective manual mapping techniques, limiting our ability to understand the dynamics controlling glacier terminus changes. I developed an automated method of mapping glacier terminus positions in satellite imagery using observations from a representative sample of Greenlands peripheral glaciers. The method is adapted from the 2D Wavelet Transform Modulus Maxima (WTMM) segmentation method, which has been used previously for image segmentation in biomedical and other applied science ...


Analysis Of Antarctic Peninsula Glacier Frontal Ablation Rates With Respect To Iceberg Melt-Inferred Variability In Ocean Conditions, M. C. Dryak, E. M. Enderlin 2020 University of Maine

Analysis Of Antarctic Peninsula Glacier Frontal Ablation Rates With Respect To Iceberg Melt-Inferred Variability In Ocean Conditions, M. C. Dryak, E. M. Enderlin

Geosciences Faculty Publications and Presentations

Marine-terminating glaciers on the Antarctic Peninsula (AP) have retreated, accelerated and thinned in response to climate change in recent decades. Ocean warming has been implicated as a trigger for these changes in glacier dynamics, yet little data exist near glacier termini to assess the role of ocean warming here. We use remotely-sensed iceberg melt rates seaward of two glaciers on the eastern and six glaciers on the western AP from 2013 to 2019 to explore connections between variations in ocean conditions and glacier frontal ablation. We find iceberg melt rates follow regional ocean temperature variations, with the highest melt rates ...


Evaluation Of Iceberg Calving Models Against Observations From Greenland Outlet Glaciers, Tristan Amaral, Timothy C. Bartholomaus, Ellyn M. Enderlin 2020 University of Idaho

Evaluation Of Iceberg Calving Models Against Observations From Greenland Outlet Glaciers, Tristan Amaral, Timothy C. Bartholomaus, Ellyn M. Enderlin

Geosciences Faculty Publications and Presentations

Frontal ablation processes at marine‐terminating glaciers are challenging to observe and difficult to represent in numerical ice flow models, yet play critical roles in modulating ice sheet mass balance. Current ice sheet models typically rely on simple iceberg calving models to prescribe either terminus positions or iceberg calving rates, but the relative accuracies and uncertainties of these calving models remain largely unconstrained at the ice sheet scale. Here, we evaluate six published iceberg calving models against spatially and temporally diverse observations from 50 marine‐terminating outlet glaciers in Greenland. We seek the single model that best reproduces observed conditions ...


Life Histories And Niche Dynamics In Late Quaternary Proboscideans From Midwestern North America: Evidence From Stable Isotope Analyses, Chris Widga, Greg Hodgins, Kayla Kolis, Stacey Lengyel, Jeff Saunders, J. Douglas Walker, Alan D. Wanamaker 2020 East Tennessee State University

Life Histories And Niche Dynamics In Late Quaternary Proboscideans From Midwestern North America: Evidence From Stable Isotope Analyses, Chris Widga, Greg Hodgins, Kayla Kolis, Stacey Lengyel, Jeff Saunders, J. Douglas Walker, Alan D. Wanamaker

Geological and Atmospheric Sciences Publications

Stable isotopes of mammoths and mastodons have the potential to illuminate ecological changes in late Pleistocene landscapes and megafaunal populations as these species approached extinction. The ecological factors at play in this extinction remain unresolved, but isotopes of bone collagen (δ13C, δ15N) and tooth enamel (δ13C, δ18O, 87Sr/86Sr) from the Midwest, USA are leveraged to examine ecological and behavioral changes that occurred during the last interglacial-glacial cycle. Both species had significant C3 contributions to their diets and experienced increasing levels of niche overlap as they approached extinction. A subset of mastodons after the last glacial maximum (LGM) exhibit low ...


Climate From The Mcmurdo Dry Valleys, Antarctica, 1986–2017: Surface Air Temperature Trends And Redefined Summer Season, Maciej K. Obryk, Peter T. Doran, Andrew G. Fountain, M. Myers, Christopher P. McKay 2020 Cascades Volcano Observatory, U.S. Geological Survey

Climate From The Mcmurdo Dry Valleys, Antarctica, 1986–2017: Surface Air Temperature Trends And Redefined Summer Season, Maciej K. Obryk, Peter T. Doran, Andrew G. Fountain, M. Myers, Christopher P. Mckay

Geology Faculty Publications and Presentations

The weather of the McMurdo Dry Valleys, Antarctica, the largest ice‐free region of the Antarctica, has been continuously monitored since 1985 with currently 14 operational meteorological stations distributed throughout the valleys. Because climate is based on a 30‐year record of weather, this is the first study to truly define the contemporary climate of the McMurdo Dry Valleys. Mean air temperature and solar radiation based on all stations were −20°C and 102 Wm−2, respectively. Depending on the site location, the mean annual air temperatures on the valleys floors ranged between −15°C and −30°C, and mean ...


Applications Of Digital Remote Sensing To Quantify Glacier Change In Glacier And Mount Rainier National Parks, Brianna Clark 2020 Stephen F. Austin State University

Applications Of Digital Remote Sensing To Quantify Glacier Change In Glacier And Mount Rainier National Parks, Brianna Clark

Electronic Theses and Dissertations

Digital remote sensing and geographic information systems were employed in performing area and volume calculations on glacial landscapes. Characteristics of glaciers from two geographic regions, the Intermountain Region (between the Rocky Mountain and Cascade Ranges) and the Pacific Northwest, were estimated for the years 1985, 2000, and 2015. Glacier National Park was studied for the Intermountain Region whereas Mount Rainier National Park was representative of the glaciers in the Pacific Northwest. Within the thirty year period of the study, the glaciers in Glacier National Park decreased in area by 27.5 percent while those on Mount Rainier only decreased by ...


The Microstructural Heterogeneity Of Ice In Jarvis Glacier, Alaska, Renée Clavette 2020 University of Maine

The Microstructural Heterogeneity Of Ice In Jarvis Glacier, Alaska, Renée Clavette

Honors College

Glacier ice behaves as a viscous fluid, where flow is controlled by a number of external and internal processes. One crucial, yet sometimes overlooked, factor is ice microstructure. Studies have shown that ice crystal (grain) size, shape, and orientation influence the viscous strength of ice, and therefore its resistance to flow and deformation. Glacier flow is also impacted by friction at the bed and lateral margins. The magnitude of flow resistance due to the lateral margins is not well quantified. The goal of this overall project is to evaluate how heterogeneous optical properties of ice are that are influenced by ...


Estimating Bedrock Fracture Density Of The Juneau Icefield, Ak, To Inform Glacial Erosion Models, Colby Rand 2020 University of Maine

Estimating Bedrock Fracture Density Of The Juneau Icefield, Ak, To Inform Glacial Erosion Models, Colby Rand

Honors College

Understanding glacial erosion rates is important because debris eroded by a glacier can impact glacier flow speeds, protect tidewater glaciers from rapid retreat, and impact the productivity of marine ecosystems. Traditionally, glacial erosion models rely on a rock’s inherent “erodibility”, typically presented as a constant, to predict how much debris will be eroded by the glacier. However, the erodibility of bedrock varies spatially as a function of its fracture density, fracture orientation, and lithology, so the notion of applying a constant erodibility term to a whole field site does not fully capture the actual bedrock dynamics of the system ...


Comments On ‘Area Changes Of Glaciers On Active Volcanoes In Latin America’ By Reinthaler And Others (2019), William Hardy Kochtitzky, Benjamin R. Edwards 2020 Dickinson College

Comments On ‘Area Changes Of Glaciers On Active Volcanoes In Latin America’ By Reinthaler And Others (2019), William Hardy Kochtitzky, Benjamin R. Edwards

Faculty and Staff Publications By Year

Reinthaler and others (2019), hereafter Reinthaler 2019, characterize ice extent on 59 volcanoes in Latin America from 1986 to 2015 using Landsat and Sentinel-2 imagery to quantify the impact of climate and eruptions on glacier evolution. Here we compare the work of Reinthaler 2019 with Kochtitzky and others (2018), hereafter Kochtitzky 2018, on Nevado Coropuna Ice Cap, and present some new analysis to highlight the challenges of seasonal snow coverage in the delineation of glaciers (Pfeffer and others, 2014; Paul and others, 2017). Nevado Coropuna Ice Cap has received significant attention (e.g. Racoviteanu and others, 2007; Silverio and Jaquet ...


La Relación Entre Cambio Climático Y Migración En Los Andes De Perú: Los Q’Ero, Taquile Y La Cordillera Blanca, Sam Hosmer-Quint 2020 SIT Study Abroad

La Relación Entre Cambio Climático Y Migración En Los Andes De Perú: Los Q’Ero, Taquile Y La Cordillera Blanca, Sam Hosmer-Quint

Independent Study Project (ISP) Collection

El cambio climático es uno de los problemas más grandes en el mundo. Los afectos de los cambios serán más graves para las personas más pobres y vulnerables. Perú es reconocido como uno de los países más vulnerables en el mundo, a causa de la presencia de glaciares tropicales, las cual son muy vulnerables a la desglaciación. Los efectos de cambio climático incluyen, entre otras cosas; el cambio de la temporada de lluvias y sequias, un aumento de la temperatura ambiental, inundaciones y tormentas severas. Todos estos factores hacen del cambio climático un riesgo para mucha gente y además, tiene ...


Climate Change Effects On Volcanoes In The Tropics: A Review Of The Deglaciation Of Antisana And Its Effects On Subsequent Water Streams And Rivers Over 20 Years, Callie C. Rominger 2020 SIT Study Abroad

Climate Change Effects On Volcanoes In The Tropics: A Review Of The Deglaciation Of Antisana And Its Effects On Subsequent Water Streams And Rivers Over 20 Years, Callie C. Rominger

Independent Study Project (ISP) Collection

Located in the Northern end of Ecuador lies the stunning glacier of Antisana which attracts many tourists and whose runoff provides a significant amount of water supply for Quito. Climate change is posing threats to many ecosystems world wide but will have a more substantial impact on the volcanoes in the tropics because they do not have a seasonally altered climate. Small changes in the air temperature can have larger impacts on these areas that are adapted to constant temperatures with seasonal precipitation changes. Climate change, in recent years, had caused an increase in the glacial retreat of the Antisana ...


Modeling The Pleistocene History Of The Greenland Ice Sheet, Benjamin Andrew Keisling 2020 University of Massachusetts Amherst

Modeling The Pleistocene History Of The Greenland Ice Sheet, Benjamin Andrew Keisling

Doctoral Dissertations

One of the most profound and immediate consequences of anthropogenic climate change is sea level rise, which in large part is driven by the melting of polar ice sheets. The Greenland Ice Sheet (GrIS) contains enough ice to raise global sea level by ~7 meters. Fluctuations of the GrIS in response to past climate change provide an opportunity to better understanding the stability of the ice sheet during periods of climatic change. In this thesis, we use numerical ice-sheet models to understand the causes and consequences of past fluctuations of the Greenland ice sheet.

In Chapters 3 and 4, we ...


Twentieth Century Black Carbon And Dust Deposition On South Cascade Glacier, Washington State, Usa, As Reconstructed From A 158‐M‐Long Ice Core, Susan D. Kaspari, Dan Pittenger, T. M. Jenk, U. Morgenstern, M. Schwikowski, N. Buenning, L. Stott 2020 Central Washington University

Twentieth Century Black Carbon And Dust Deposition On South Cascade Glacier, Washington State, Usa, As Reconstructed From A 158‐M‐Long Ice Core, Susan D. Kaspari, Dan Pittenger, T. M. Jenk, U. Morgenstern, M. Schwikowski, N. Buenning, L. Stott

All Faculty Scholarship for the College of the Sciences

Light absorbing particles (LAPs) include black carbon (BC) and mineral dust and are of interest due to their positive radiative forcing and contribution to albedo reductions and snow and glacier melt. This study documents historic BC and dust deposition as well as their effect on albedo on South Cascade Glacier (SCG) in Washington State (USA) through the analysis of a 158‐m (139.5‐m water equivalent [w.e.]) ice core extracted in 1994 and spanning the period 1840–1991. Peak BC deposition occurred between 1940 and 1960, when median BC concentrations were 16 times higher than background, likely dominated ...


Sliding Relations For Glacier Slip With Cavities Over Three‐Dimensional Beds, Christian Helanow, Neal R. Iverson, Lucas K. Zoet, Olivier Gagliardini 2020 Iowa State University

Sliding Relations For Glacier Slip With Cavities Over Three‐Dimensional Beds, Christian Helanow, Neal R. Iverson, Lucas K. Zoet, Olivier Gagliardini

Geological and Atmospheric Sciences Publications

Results of glacier flow models and associated estimates of future sea level rise depend sensitively on the prescribed relation between shear stress and slip velocity at the glacier bed. Using a fully three‐dimensional numerical model of ice flow, we compute steady‐state sliding relations for where ice slips over a rock bed with three‐dimensional, periodic topography. In agreement with studies of two‐dimensional beds, water‐filled cavities that form down‐glacier from bedforms cause basal shear stress to peak at a threshold slip velocity and decrease at higher velocities (i.e., rate‐weakening drag). However, the shear stress ...


Future Evolution Of Greenland's Marine-Terminating Outlet Glaciers, G. A. Catania, L. A. Stearns, T. A. Moon, E. M. Enderlin, R. H. Jackson 2020 University of Texas at Austin

Future Evolution Of Greenland's Marine-Terminating Outlet Glaciers, G. A. Catania, L. A. Stearns, T. A. Moon, E. M. Enderlin, R. H. Jackson

Geosciences Faculty Publications and Presentations

Mass loss from the Greenland ice sheet (GrIS) has increased over the last two decades in response to changes in global climate, motivating the scientific community to question how the GrIS will contribute to sea-level rise on timescales that are relevant to coastal communities. Observations also indicate that the impact of a melting GrIS extends beyond sea-level rise, including changes to ocean properties and circulation, nutrient and sediment cycling, and ecosystem function. Unfortunately, despite the rapid growth of interest in GrIS mass loss and its impacts, we still lack the ability to confidently predict the rate of future mass loss ...


Esd Ideas: Why Are Glaciations Slower Than Deglaciations?, Christine J. Ramadhin, Chuixiang Yi 2020 CUNY Graduate Center

Esd Ideas: Why Are Glaciations Slower Than Deglaciations?, Christine J. Ramadhin, Chuixiang Yi

Publications and Research

The Earth’s climate during the Quaternary is dominated by short warm interglacials and longer cold glaciations paced by external forcings such as changes in insolation. Although not observed in the solar radiation changes, the time series of the cycles display asymmetry since transitions to full glacial conditions are slower than the termination of glaciations. Here an idea is proposed for the slower transition by identifying and describing two negative sea ice feedbacks dominant during the glaciation process that could serve as a control on the intermediate stage and decrease the pace of the process.


Glacial Earthquakes And Precursory Seismicity Associated With Thwaites Glacier Calving, J. Paul Winberry, Audrey D. Huerta, Sridhar Anandakrishnan, Richhard C. Aster, Andrew A. Nyblade, Douglas A. Wiens 2020 Central Washington University

Glacial Earthquakes And Precursory Seismicity Associated With Thwaites Glacier Calving, J. Paul Winberry, Audrey D. Huerta, Sridhar Anandakrishnan, Richhard C. Aster, Andrew A. Nyblade, Douglas A. Wiens

All Faculty Scholarship for the College of the Sciences

We observe two (~MS 3) long‐period (10–30 s) seismic events that originate from the terminus of Thwaites Glacier, Antarctica. Serendipitous acquisition of satellite images confirm that the seismic events were glacial earthquakes generated during the capsizing of icebergs. The glacial earthquakes were preceded by 6 days of discrete high‐frequency seismic events that can be observed at distances exceeding 250 km. The high‐frequency seismicity displays an increasing rate of occurrence, culminating in several hours of sustained tremor coeval with the long‐period events. A series of satellite images collected during this precursory time period show that ...


Chronology Of Advance And Recession Dynamics Of The Southern Green Bay Lobe Of The Laurentide Ice Sheet, South-Central Wisconsin, Usa, Eric C. Carson, John W. Attig, J. Elmo Rawling III, Paul R. Hanson, Stefanie E. Dodge 2020 University of Wisconsin-Madison

Chronology Of Advance And Recession Dynamics Of The Southern Green Bay Lobe Of The Laurentide Ice Sheet, South-Central Wisconsin, Usa, Eric C. Carson, John W. Attig, J. Elmo Rawling Iii, Paul R. Hanson, Stefanie E. Dodge

Papers in Natural Resources

We used a combination of accelerator mass spectrometry (AMS) radiocarbon dating, optically stimulated luminescence (OSL) age estimates, and stratigraphic data from cores collected along the southern margin of the Green Bay Lobe (GBL) of the Laurentide Ice Sheet to provide new information on the timing and dynamics of the end of advance of the GBL and the dynamics of the ice sheet while very near its maximum position. Coring at multiple sites along the margin of the GBL indicate that ice had reached a stable position near its maximum extent by 24.7 ka; that ice advanced several kilometers to ...


Rock Glacier Development In The San Juan Mountains, Brandon K. Bailey 2020 University of Denver

Rock Glacier Development In The San Juan Mountains, Brandon K. Bailey

Electronic Theses and Dissertations

Rock glaciers are common landform features found in deglaciated alpine areas. They are commonly used in the study of climatic changes throughout the Holocene and the reconstruction of neoglacial chronologies. For this research, Schmidt hammer rebound values, weathering rind thicknesses, and the length of lichen thalli diameters found on rock glacier surfaces are used to investigate their effectiveness as field-based relative age determination techniques. Additionally, the ability to identify periods of neoglacial activity using these methods is assessed in two neighboring cirque basins in the San Juan Mountains of Colorado. 41 field sites across three rock glaciers are established with ...


Geochemical Flux Analysis Of Glacial River Runoff For Sólheimajökull, Iceland, Jessica Garrison 2020 Western Kentucky University

Geochemical Flux Analysis Of Glacial River Runoff For Sólheimajökull, Iceland, Jessica Garrison

Mahurin Honors College Capstone Experience/Thesis Projects

Geochemical fluxes in aqueous studies are an essential component of research to understand weathering and changes in a hydrologic system. These data can indicate any discrepancies, outliers, or gradual changes in a water environment to gain information on pollutants, carbon cycles, biological input, etc. Glacial melt is the majority of the surface water present throughout the country. The melting amount is increasing with the temperatures, which can be monitored by the changes in geochemical flux during increased discharge in glacial rivers. A high-resolution data set of Sόlheimajökull Glacier in Iceland was used to determine how changing climatic conditions for the ...


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