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Full-Text Articles in Physical Sciences and Mathematics
Marine Ice Modification Of Fringing Ice Shelf Flow, Christina L. Hulbe, R. Johnston, Ian R. Joughin, Ted A. Scambos
Marine Ice Modification Of Fringing Ice Shelf Flow, Christina L. Hulbe, R. Johnston, Ian R. Joughin, Ted A. Scambos
Geology Faculty Publications and Presentations
Locally derived ice is often observed to fill through-cutting rifts and uneven fronts in ice shelves. That ice may nucleate as fast ice at the shelf front, by growth at the sea surface within rifts, or by basal accretion. Here, we investigate the role of such ice in the flow of the Brunt Ice Shelf and adjacent Stancomb-Wills ice tongue, along the Caird Coast of Antarctica. Much of the shelf system is severely rifted, with locally derived ice filling the space between rift walls and around ice rafts. A series of numerical experiments that account for thermal properties of the …
Catastrophic Ice Shelf Breakup As The Source Of Heinrich Event Icebergs, Christina L. Hulbe, D. R. Macayeal, George H. Denton, Johan Kleman, Thomas Lowell
Catastrophic Ice Shelf Breakup As The Source Of Heinrich Event Icebergs, Christina L. Hulbe, D. R. Macayeal, George H. Denton, Johan Kleman, Thomas Lowell
Geology Faculty Publications and Presentations
Heinrich layers of the glacial North Atlantic record abrupt widespread iceberg rafting of detrital carbonate and other lithic material at the extreme-cold culminations of Bond climate cycles. Both internal (glaciologic) and external (climate) forcings have been proposed. Here we suggest an explanation for the iceberg release that encompasses external climate forcing on the basis of a new glaciological process recently witnessed along the Antarctic Peninsula: rapid disintegrations of fringing ice shelves induced by climate-controlled meltwater infilling of surface crevasses. We postulate that peripheral ice shelves, formed along the eastern Canadian seaboard during extreme cold conditions, would be vulnerable to sudden …
Subglacial Thermal Balance Permits Ongoing Grounding Line Retreat Along The Siple Coast Of West Antarctica, Byron R. Parizek, Richard B. Alley, Christina L. Hulbe
Subglacial Thermal Balance Permits Ongoing Grounding Line Retreat Along The Siple Coast Of West Antarctica, Byron R. Parizek, Richard B. Alley, Christina L. Hulbe
Geology Faculty Publications and Presentations
Changes in the discharge of West Antarctic ice streams are of potential concern with respect to global sea level. The six relatively thin, fast-flowing Ross ice streams are of interest as low-slope end-members among Antarctic ice streams. Extensive research has demonstrated that these "rivers of ice" have a history of relatively high-frequency (óO(100) years), asynchronous discharge variations with evolving lateral boundaries. Amidst this variability, a ~1300 km grounding-line retreat has occurred since the Last GlacialMaximum. Numerical studies of Ice Stream D (Parizek and others, 2002) indicate that a proposed thermal-regulation mechanism(Clarke and Marshall, 1998; Hulbe and MacAyeal,1999; Tulaczyk and others, …
The Role Of Lateral And Vertical Shear In Tributary Flow Toward A West Antarctic Ice Stream, Christina L. Hulbe, Weili Wang, Ian R. Joughin, Martin J. Siegert
The Role Of Lateral And Vertical Shear In Tributary Flow Toward A West Antarctic Ice Stream, Christina L. Hulbe, Weili Wang, Ian R. Joughin, Martin J. Siegert
Geology Faculty Publications and Presentations
Narrow lateral shear margins are the most distinctive visual feature of the West Antarctic ice streams. Large shear stresses within these layers support the majority of the gravitational driving stress within a fast-flowing ice stream.The present contribution looks upstream, to the tributaries that feed ice-stream onsets, and considers the effects of both horizontal and vertical shear on their flow. Numerical and direct simulations of vertical and horizontal shear are used.Vertical shear, simulated using an anisotropic flow law, is of particular interest.We conclude that by isolating overlying ice from large-amplitude variations in bed elevation -vertical shear margins - play an important …
An Ice-Shelf Model Test Based On The Ross Ice Shelf, D. R. Macayeal, V. Rommelaere, P. Huybrechts, Christina L. Hulbe, J. Determann, C. Ritz
An Ice-Shelf Model Test Based On The Ross Ice Shelf, D. R. Macayeal, V. Rommelaere, P. Huybrechts, Christina L. Hulbe, J. Determann, C. Ritz
Geology Faculty Publications and Presentations
A standard numerical experiment featuring the Ross Ice Shelf, Antarctica, is presented as a test package for the development and intercomparison of ice-shelf models. The emphasis of this package is solution of stress-equilibrium equations for an ice-shelf velocity consistent with present observations. As a demonstration, we compare five independently developed ice-shelf models based on finite-difference and finite-element methods. Our results suggest that there is little difference between finite-element and finite-difference methods in capturing the basic, large-scale flow features of the ice shelf. We additionally show that the fit between model and observed velocity depends strongly on the ice-shelf temperature field …