Physical Sciences and Mathematics Commons^™

Snow Distribution And Influence In Taylor Valley, Antarctica, Using Remote Sensing, Katherine Mcnulty, Peter Doran, Mark Salvatore, Suniti Karunatillake

LSU Master's Theses

The McMurdo Dry Valleys is the largest ice-free area in Antarctica, but seasonal snow covers the valley floors sporadically throughout the year. In this study, a model to estimate areal snow coverage from satellite imagery was created. An area-volume model was created to estimate the amount of snow water equivalent (SWE) from the snow area extracted from the imagery. Snow cover influences the total albedo, the hydrologic budget, and the soil moisture and soil temperature in Taylor Valley (TV). Quantifying snow precipitation in TV is challenging because snow redistributes with winds, sublimates, or melts within a short period. Previous estimates …

Antarctic Ice Sheet Stability During Warm Periods: Integrating Numerical Modeling With Geologic Data, Anna Ruth W. Halberstadt

Doctoral Dissertations

Sea level rise is one of the major social and environmental challenges that threatens modern civilization, yet the response of polar ice sheets to future warming is deeply uncertain. Mass loss from the Antarctic Ice Sheet is projected to dominate global sea level rise in the near future, but how much, and when, remains a key unknown. The challenges associated with projecting Antarctica’s future sea level contribution are derived from a knowledge gap of physical ice sheet processes in a world warmer than today, and a lack of understanding of climatic thresholds that drive potentially irreversible retreat. Future and even …

Microfabric Analysis Of Mid-Pliocene Amundsen Sea Interglacial Sediments Demonstrates A Link Between Iceberg Melt And Diatom Productivity (Iodp Exp. 379), Heather Leanne Furlong

Graduate Research Theses & Dissertations

Anthropogenically induced climate change in the polar regions has rapidly become an emergent global issue, especially for low-lying coastal communities, which are most affected by sea-level rise. The future of the West Antarctic Ice Sheet (WAIS) is of significant concern due to its history of instability and retreat, especially in light of the observed ongoing changes. Establishing rates of retreat is critical to forecasting future behavior of the WAIS, and previous studies have been unable to establish rates of ice sheet collapse in part because Antarctic continental shelf records are impacted by erosional hiatuses. In 2019, International Ocean Discovery Program …

Causes And Characteristics Of Electrical Resistivity Variability In Shallow (<4 M) Soils In Taylor Valley, East Antarctica, William S. Gutterman

LSU Master's Theses

The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are characterized as a polar desert environment. Soils in the region are typically very dry (<1% soil water by weight) and remain frozen for most of the year. Increases in air temperature and incoming solar radiation during the austral summer generate meltwater from glaciers, ground ice, and snow patches supplying moisture to soils and altering the physical and chemical makeup of the subsurface. Previous studies have utilized airborne electromagnetic surveys (AEM) to analyze groundwater systems in the deep subsurface but have not yet examined soil moisture in the shallow (<4 m) subsurface. Here, I used electrical resistivity data from two AEM surveys (2011 and 2018) and soil geochemical data from three transects to characterize the spatial heterogeneity of soil properties in the near-subsurface of lower Taylor Valley. Soil resistivities from 2011 and 2018 range from 33.2 Ωm to 3535 Ωm with low elevations of <100 meters above sea level (masl) typically displaying the lowest resistivities and high elevations displaying greater resistivities. Liquid brine fractions were empirically estimated from electrical resistivity values using Archie’s Law and range from 0.3% to 68.2% for soils with resistivities <200 Ωm. Additionally, soil transect data show greater percentages of fine-grained sediments (<63 µm) exist at elevations <100 masl where soil resistivities begin decreasing. Resistivity variability in the subsurface is ultimately controlled by the site history, local and regional climate, soil salinity, soil moisture, soil lithology.

Miocene-Pleistocene Diatom Oxygen Isotope And Biogenic Silica Record From Iodp Site U1523, Ross Sea, Antarctica, Donald James Mclennan

Graduate Research Theses & Dissertations

The West Antarctic Ice Sheet (WAIS) plays a significant role in Earth’s climate. WAIS is currently retreating due to changes in wind-driven oceanic currents resulting in an increasing flux of warm waters to ice margins. Brine rejection in the Ross Sea is also major source of High Salinity Shelf water (HSSW) and Antarctica Bottom Waters (AABW), which creates a stratified ocean and plays a significant role in regulating Earth’s climate. Currently, there are very limited proxies that can quantify the variable input of HSSW formation on geologic time scales. Here we provide a 18Odiatom and biogenic silica (BSi) record which …

Plio-Pleistocene Paleoceonography Of The Ross Sea, Antarctica Based On Foraminifera From Iodp Sites U1523, U1522, And U1521, Julia Seidenstein

Masters Theses

The West Antarctic Ice Sheet (WAIS) is currently thinning and retreating because shifting oceanic currents are transporting warmer waters to the ice margin, which could lead to a collapse of the ice sheet and global sea level rise. International Ocean Discovery Program (IODP) Expedition 374 sailed to the Ross Sea in 2018 to study the history of the WAIS over the last 20 million years. Previous geologic drilling projects into Ross Sea sediments that record the history of the WAIS (DSDP Leg 28, RISP, MSSTS, Cape Roberts Drilling Project, ANDRILL), as well as modeling studies, show considerable variability of ice-sheet …

Model-Based Estimates Of The Timing Of Brine Flux Into The Victoria Land Basin From The Mcmurdo Dry Valleys, Antarctica, Valerie Nicole Voisin

Graduate Research Theses & Dissertations

Submarine groundwater discharge (SGD) at a continental scale is one of the least constrained components of the hydrologic cycle and may represent a significant flux of iron and silica waters to the global ocean. Quantifying SGD along the Antarctic margin is complicated by complex subglacial and subsurface hydrogeology and limited observational data. Airborne transient electromagnetic (AEM) surveys have identified extensive high-salinity subsurface brines in the McMurdo Dry Valleys (MDV) that are hydrologically connected to surface features in the MDV (e.g. Taylor Glacier, saline lakes) and are potentially a significant source of SGD to McMurdo Sound. A 2D numerical model was …

Evidence Of Subglacial Brine Inflow And Wind-Induced Mixing From High Resolution Temperature Measurements In Lake Bonney, Antarctica, Jade Lawrence

LSU Master's Theses

Hypersaline brine beneath Taylor Glacier enters proglacial West Lobe Lake Bonney (WLB) subglacially as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the water column of WLB. Because of the extremely high salinities below the chemocline in WLB, density is determined almost entirely by salinity and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude in to the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. This study …

Seismic Array Studies Of Antarctica And Madagascar, Martin James Pratt

Arts & Sciences Electronic Theses and Dissertations

The scope of this dissertation is broad, involving seismic array studies from Antarctica and Madagascar, and includes aspects of glaciology and oceanography as well as solid Earth geophysics. Chapter 2 focuses on the study of stickslip motion of the Whillans Ice Stream, West Antarctica. It includes methods combining seismic array and GPS time series, from ice stream based-sensors, to determine source dynamics in the framework of an earthquake source. The source characteristics are then analyzed to explain far-field seismic observations of ice stream- sourced surface waves detected throughout West Antarctica. Locations of asperities, or sticky- spots, that cause the Whillans …

Processing And Interpretation Of Three-Component Vertical Seismic Profile Data, Ross Sea, Antarctica, Meltem Akan

Graduate Theses & Non-Theses

The Antarctic Geological Drilling Program (ANDRILL) AND-2A drill hole was drilled, cored and logged in southern McMurdo Sound (SMS) in the western Ross Sea, Antarctica during the austral summer of 2007. A single near-offset, over-sea ice vertical seismic profile (VSP) was collected in the AND-2A drill hole as a part of the logging program. The source for VSP data collection was a Generator Injector (GI) air-gun which was suspended by a cable through a hole made in the sea ice. The reason for selecting a GI air gun was the minimization of the bubble pulse effects which are prevalent in …

Ocean Forcing Of Quaternary East Antarctic Ice Sheet Evolution: An Ice-Proximal Sedimentary Perspective, Michelle E. Guitard

USF Tampa Graduate Theses and Dissertations

Antarctica and the Southern Ocean play a critical role in Earth’s climate system. Antarctica’s ice sheets contain enough ice to raise global sea level by ~58 m, and the Southern Ocean distributes climate signals and nutrients to the major ocean basins and the deep ocean. Antarctica’s largest ice sheet, the East Antarctic Ice Sheet (EAIS), was considered stable compared to those in West Antarctica and the Antarctic Peninsula because it was thought to be grounded above sea level. However, subglacial topography now reveals vast submarine basins and measurements of ice velocity in the Pacific sector indicate marine-terminating outlet glacier thinning …

Examining Antarctica From A Geodynamic Perspective: Backstripping, Ice Thickness, Tectonics And Erosion, Travis Gary Hayden

Dissertations

I have applied the principles of basin analysis and geodynamics to several cores recovered from on or near the Antarctic continent to answer 2 independent questions about the tectonic evolution of Antarctica; as well as estimate the thickness of the Antarctic Ice Sheet at the Last Glacial Maximum.

I developed, and applied a modification of the backstripping modeling technique to compensate for the loading and erosion of glacial ice at the AND-1B site by combining a backstripping driven inverse model, with a driven ice-load model. This modification allowed me to identify and constrain the timing of major pulses of subsidence …

Toward A Better Understanding Of Recent Warming Of The Central West Antarctic Ice Sheet From Shallow Firn Cores, Jessica Williams

Theses and Dissertations

Previous studies have shown significant warming through the 1990s in the West Antarctic Ice Sheet (WAIS); but the records used in those studies end in early 2000, preventing trend analysis into the latest decade. Fourteen new snowpits and firn cores were collected in 2010 and 2011, which have been combined with previous cores to extend the isotopic records over WAIS. Significance of these isotopic patterns across WAIS was determined and is used to re-evaluate the warming of the West Antarctic interior over recent decades. We find that isotopic records longer than 50 years are needed to assess climate trends due …

Temporal Trends In West Antarctic Accumulation Rates: Evidence From Observed And Simulated Records, Landon Kelly Burgener

Theses and Dissertations

Reconstructed snow accumulation rate observations from five new firn cores show a statistically significant negative trend in accumulation rates over the past four decades across the central West Antarctic ice sheet. A negative temporal trend in accumulation is unexpected in light of rising surface temperatures and simulations run by GCMs. Both the magnitude of the mean accumulation rates and the range of interannual variability observed in the new records compares favorably to older records, suggesting that the new accumulation rate records may serve as a regional proxy for recent temporal trends in West Antarctic accumulation rates. The observed negative trend …

Distribution Of Patterned Ground And Surficial Deposits On A Debris-Covered Glacier Surface In Mullins Valley And Upper Beacon Valley, Antarctica, Andrew M. Lorrey

Electronic Theses and Dissertations

Beacon Valley is located in the western Dry Valleys, Antarctica, adjacent to the East Antarctic Ice Sheet (EAIS). The surficial material on the floor of Beacon Valley is segmented into large polygonal landforms separated by trenches. Buried beneath the polygons and surficial material is massive ground ice. One hypothesis is that the buried ice in upper Beacon Valley is glacier ice originating from local debris-covered glaciers. The networks of polygons and trenches form as the buried ice undergoes thermal contraction and sublimation. Contraction cracks that penetrate the surficial material and buried ice in Beacon Valley contain Late Miocene age volcanic …