Physical Sciences and Mathematics Commons^™

Collaborative Research: Subglacial Water Intrusion In Greenland, Gordon K. Oswald

University of Maine Office of Research Administration: Grant Reports

The project's goals are:

• To analyse radio echo sounding data acquired over the Greenland Ice Sheet by the University of Kansas / CReSIS team with the objective of discriminating between frozen and thawed conditions at the bed of the ice sheet.
• To provide maps of the bed state, with the aim of making them available via the National Snow and Ice Data Centre.
• To support ice sheet modelling activities by providing information on the bed state, thus related to the temperature at the bed and the rheological conditions at the bed.
• To make available to educational establishments information on the …

Collaborative Research: Subglacial Water Intrusion In Greenland, Gordon K. Oswald

University of Maine Office of Research Administration: Grant Reports

A full understanding of the flow and dynamics of an ice sheet will require knowledge of the state of its subglacial interface. While the topography of the Greenland Ice Sheet bed has been studied by radio echo sounding, its state in terms of melting and freezing, which itself affects its future evolution, has been inferred from numerical models, rather than from direct evidence.

This project is for analysis of existing radar echo data gathered under the PARCA and CReSIS programs, with the objective of generating direct evidence of the extent of subglacial water in Greenland and providing the glaciological community …

Quantifying Syntectonic Weakening In Deep Orogenic Crust, Christopher Gerbi

University of Maine Office of Research Administration: Grant Reports

The primary intellectual impact of this project will be in improving our understanding of the mechanics that shape the Earth's crust. In recent years, earth scientists have used the increasing body of geodetic data towards that end, but the mechanical properties of the middle and lower crust remain only loosely constrained. This project focuses on the magnitude of strain weakening in shear zone networks. In detail, the research will explore the grain-scale and outcrop-scale deformation mechanisms in minerals that lead to this weakening, followed by modeling of the results to understand the weakening process on the larger scale. These conceptual …

Collaborative Research: Multiscale Analysis Of Geological Structures That Influence Crustal Seismic Anisotropy, Senthil Vel, Scott E. Johnson

University of Maine Office of Research Administration: Grant Reports

This project is a study of crustal material anisotropy with a focus on macroscale structural geometries and how they will modify the seismic response of rock fabrics. Seismic anisotropy is the cumulative interplay between propagating seismic waves and anisotropic earth material that manifests itself through the directional dependence of seismic wave speeds. Unraveling this effect in deformed crustal terranes is complex due to several factors, such as 3D geological geometry and heterogeneity, microscale fabric, bending of seismic raypaths due to velocity gradients, field experiments that may not offer full azimuthal coverage, and the observation of anisotropy as second-order waveform or …

Collaborative Research: Constraints On The Last Ross Ice Sheet From Glacial Deposits In The Southern Transantarctic Mountains, Brenda Hall

University of Maine Office of Research Administration: Grant Reports

This award supports a project to study the former thickness and retreat history of Shackleton and Beardmore Glaciers which flow through the Transantarctic Mountains (TAMs) into the southern Ross Sea. Lateral moraine deposits along the lower reaches of these major outlet glaciers will be mapped and dated and the results will help to date the LGM and constrain the thickness of ice where it left the Transantarctic Mountains and flowed into the Ross Sea. The intellectual merit of the project is that the results will allow scientists to distinguish between models of ice retreat, which have important implications for former …

Collaborative Research: Sensitivity Of Local Glaciers In Central East Greenland To Holocene Climate Change, Brenda Hall

University of Maine Office of Research Administration: Grant Reports

This award will support an investigation of Holocene glacier fluctuations in the Scoresby Sund region of central East Greenland (~70-72¿N, 22-28¿W) along a transect from a coastal maritime setting to the continental conditions adjacent to the Greenland Ice Sheet. The 'Intellectual Merit' of the proposed study lies in the potential to affirm, or otherwise, the widely-held view that the scale of glacier and ice sheet change being observed today in Greenland is not unique in the Holocene. The current recession of glaciers in the Scoresby Sund region is exposing sub-fossil vegetation that grew at times when glaciers were smaller than …

Using Hydrologic Measurements To Investigate Free Phase Gas In A Maine Peatland, Usa, Christiaan Bon

Electronic Theses and Dissertations

Northern Peatlands cover more than 350 million ha (~3 percent of Earth’s surface) and are an important source of methane (CH4) and other biogenic gases contributing to climate change. Free phase gas (FPG) accumulation and episodic release has recently been recognized as an important mechanism for biogenic gas flux from peatlands. It is likely that gas production and groundwater flow are interconnected in peatlands: groundwater flow influences gas production by regulating geochemical conditions and nutrient supply available for methanogenesis while FPG influences groundwater flow through a reduction in peat permeability and by creating excess pore fluid pressures. Water samples collected …

Improving The Performance Of The Parallel Ice Sheet Model On A Large-Scale, Distributed Supercomputer, Timothy J. Morey

Electronic Theses and Dissertations

In this thesis, we describe our work to understand and improve the performance and scalability of the Parallel Ice Sheet Model (PISM) on the Ranger supercomputer. PISM enables the simulation of large-scale ice sheets, such as those found in Greenland and Antarctica, which are of particular interest to climate scientists due to their potential to contribute to sea-level rise.

PISM has a unique parallel architecture that is designed to take advantage of the computational resources available on state-of-the-art supercomputers. The problem, however, is that even though PISM can run without modifcation on a supercomputer, it is generally unable to do …

Investigating The Controls On Surface Snow Δ18o Values In The Coastal Northeast Pacific: Implications For Paleoclimate Interpretations, Matthew C. Koehler

Honors College

Stable water isotope ratios (18O and D) in snow pit (Juneau Icefield) and fresh snow (Eclipse Icefield) samples are included in a compilation of all available snow isotope data from coastal Alaska, and used to evaluate observed isotope shifts in regional paleoclimate records. I compiled existing isotope data in coastal Alaska (primarily the Saint Elias Range) in order to better understand the elevation dependence of stable atmospheric water isotope ratios in the region. The values that make up the compilation are reflective of multiple fractionation regimes associated with synoptic scale cyclonic events, described using the Cyclone-Water Isotope Model (Holdsworth and …

Ltreb: Biogeochemical Mechanisms Of Response In The Third Decade Of Whole-Ecosystem Experimental Manipulations At The Bear Brook Watershed In Maine (Bbwm), Ivan J. Fernandez, Stephen A. Norton, Lindsey E. Rustad

University of Maine Office of Research Administration: Grant Reports

This grant will support the Bear Brook Watershed in Maine (BBWM) where research has been conducted for approximately 20 years on the effects of atmospheric sulfur and nitrogen deposition on forests. The research is conducted on two watersheds, each drained by a first order stream. One is treated bimonthly by helicopter to simulate atmospheric deposition of sulfur and nitrogen. Over the past 20 years, this research has identified and verified key factors governing forest response to air pollution, and also revealed major gaps in our understanding that are critical to determining the success of current and potential future regulations under …

Application Of Boron Isotopes To Constrain The Depositional Environment Of The Precursors To Proterozoic Granulite-Facies Borosilicate Paragneisses, Larsemann Hills, Antarctica, Edward Grew

University of Maine Office of Research Administration: Grant Reports

Intellectual Merit. Major challenges in understanding high P-T granulite facies terranes are identifying the original protolith rocks and the tectonic environment in which they were originally deposited. This project focuses on granulitic gneisses exposed in the Larsemann Hills, Prydz Bay (East Antarctica). These rocks are considered to be metasediments (paragneisses), but, despite more than 20 years of intense study, the tectonic framework of deposition of the original rocks is still debated. However the origin of these rocks has important implications for determining the assembly of the ancient Gondwana continent. The unique B-rich character of the rocks offers potential insight into …