Ice stream Research Papers - Academia.edu (original) (raw)

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- Physical Geography, Earth Sciences, Geology, Geophysics
- by Jonathan Bamber
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- Remote Sensing, Multidisciplinary, Topography, Volume
- by michel guiraud
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- Earth Sciences, Geology, Shear Zone, Microstructures
- by Ilker Fer
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- Oceanography, Microstructure, Turbulence, Heat Transfer
- by S. Tulaczyk
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- Geology, Earth Surface Processes, Ice stream
- by Maarit Middleton
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- Geology, Flute, Younger Dryas, Sedimentary Geology
- by Miriam Jackson
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- Glaciology, Shear Stress, Recrystallization, Ice stream
- by Olav Lian
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- Geology, Earth Surface Processes, Ice stream
- by Emmanuel Le Meur
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- Climate Change, Climate variability, Climate, Multidisciplinary
- by Robert Mulvaney
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- Earth Sciences, Geology, Sea Ice, Ice stream
- by Hermann Engelhardt
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- Geology, Thermodynamics, Multidisciplinary, Borehole
- by Sivaprasad Gogineni
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- Geology, Remote Sensing, Multidisciplinary, Kriging
- by Hester Jiskoot
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- Remote Sensing, Image Analysis, Comparative Study, Multidisciplinary
- by S. Tulaczyk
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- Water, Hydraulics, Nonlinear dynamics, Theory
- by Carl Regnell
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- Glacial Geology, Quaternary Geology, Paleo-glaciology, Paleo-ice streams
- by Eiliv Larsen
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- Geology, Geochemistry, Geophysics, Ice stream
- by Samuel Kelley
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- Archaeology, Geology, Quaternary Science, Deglaciation
- by Peter Wadhams
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- Multidisciplinary, Sea Ice, Concentration, Models

Evans Ice Stream, West Antarctica, has five tributaries and a complex grounding zone. The grounding zone of Evans Ice Stream, between the landward and seaward limits of tidal flexing, was mapped using SAR interferometry. The width of the mapped grounding zone was compared with that derived from an elastic beam model, and the tidal height changes derived from interferometry were compared with the results of a tidal model. Results show that in 1994 and 1996 the Evans grounding zone was located up to 100 km upstream of its location in the BEDMAP dataset. The grounding line of Evans Ice Stream is subjected to 5 m vertical tidal forcing, which would clearly affect ice-stream flow.

- by Tavi Murray
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- Cartography, Geophysics, Modeling, Localization
- by Christian Vincent
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- Climate Change, Climate variability, Climate, Multidisciplinary
- by David Rippin
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- Glaciology, Sea Level, Topography, Glaciers

The surface velocity field of Devon Ice Cap, Nunavut, Canada, was mapped using interferometric synthetic aperture radar (InSAR). Ascending European Remote-sensing Satellite 1 and 2 (ERS-1/-2) tandem mode data were used for the western and southeast sectors, and 3 day repeat pass ERS-1 imagery for the northeast sector. Speckle-tracking procedures were used with RADARSAT 1 imagery to obtain surface velocities over the terminus of Belcher Glacier (a major calving front) where decorrelation between ERS data occurred. The InSAR data highlight a significant contrast in ice-flow dynamics between the east and west sides of the ice cap. Ice movement west of the main north south divide is dominated by relatively uniform 'sheet' flow, but three fast-flowing outlet glaciers that extend 14 23 km beyond the ice-cap margin also drain this region. Several outlet glaciers that extend up to 60 km inland from the eastern margin drain the eastern side of the ice cap. The dominant ice-flow regimes were classified based on the relationship between the driving stress (averaged over a length scale of ten ice thicknesses) and the ratio of surface velocity to ice thickness. The mapped distribution of flow regimes appears to depict the spatial extent of basal sliding across the ice cap. This is supported by a close relationship between the occurrence of flow stripes on the ice surface and flow regimes where basal sliding was found to be an important component of the glacier motion. Iceberg calving rates were computed using measured surface velocities and ice thicknesses derived from airborne radio-echo sounding. The volume of ice calved between 1960 and 1999 was estimated to be 20.5 ± 4.7 km3 (or 0.57 km3 a-1). Approximately 89% of this loss occurred along the eastern margin. The largest single source is Belcher Glacier, which accounts for ˜50% of the total amount of ice calved.

- by David Burgess
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- Cartography, Glaciology, Synthetic Aperture Radar, Iceberg
- by Bernd Kulessa
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- Glaciology, Hydrogeology, Sensitivity Analysis, Uncertainty

Kveithola Trough, an EW trending glacial trough in the NW Barents Sea, was surveyed for the first time during the EGLACOM cruise of R/V OGS-Explora in summer 2008. Swath bathymetry shows that the seafloor is characterized by EW trending... more

- by Paolo Diviacco
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- Earth Sciences, Geology, Climate Change, Marine Geology

The entire continent of Antarctica was mapped at a 25 meter resolution with synthetic aperture radar (SAR) during the Radarsat Antarctic Mapping Project (RAMP) over a 30 day period in the fall of 1997 providing a static “snapshot” of the ice sheet. Since Radarsat-l has a 24-day orbit cycle, repeat-pass interferometric SAR (InSAR) data was also acquired. The extensive InSAR

- by hg sohn
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- Glaciology, Remote Sensing, Hydrology, Dynamics

- by Doug Mair
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- Cartography, Glaciology, Synthetic Aperture Radar, Iceberg

Mega-scale glacial lineations (MSGLs) are longitudinally aligned corrugations (ridge–groove structures 6–100 km long) in sediment produced subglacially. They are indicators of fast flow and a common signature of ice-stream beds. We develop a qualitative theory that accounts for their formation, and use numerical modelling, and observations of ice-stream beds to provide supporting evidence. Ice in contact with a rough (scale of 10–103 m) bedrock surface will mimic the form of the bed. Because of flow acceleration and convergence in ice-stream onset zones, the ice-base roughness elements experience transverse strain, transforming them from irregular bumps into longitudinally aligned keels of ice protruding downwards. Where such keels slide across a soft sedimentary bed, they plough through the sediments, carving elongate grooves, and deforming material up into intervening ridges. This explains MSGLs and has important implications for ice-stream mechanics. Groove ploughing provides the...

- by Miquel Canals
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- Glaciology, Morphometry, Drag, Sediments
- by Richard Forster
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- Glaciology, Remote Sensing, Hydrology, Dynamics

Modulation of the flow of Rutford Ice Stream, Antarctica, has been reported previously at semi-diurnal, diurnal, fortnightly and semi-annual periods. A model that includes non-linear response to tidal forcing has been shown to fit closely observations at fortnightly frequencies. Here we examine that model further and test its fit at a larger set of observed frequencies, including the large semi-annual displacement. We show analytically that, when forced by major tidal terms, the model (using a basal shear stress exponent m = 3) predicts several discrete response periods from 4 hours to 0.5 years. We examine a 1.5 year GPS record from Rutford Ice Stream and find that the model, when forced by a numerical tide model, is able to reproduce the reported semi-annual signal. We confirm that about 5% of the mean flow is due solely to the (m = 3) non-linear response to tidally varying basal shear stress. Our best-fitting set of model parameters is similar to those originally reported using a...

- by Tavi Murray
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- Glaciology, Models, Data Quality, Shear Stress
- by Tavi Murray
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- Sea Level, Sensitivity Analysis, Global Positioning System, Multidisciplinary
- by Dennis Darby
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- Earth Sciences, Abrupt Climate Change, Late Pleistocene, Thermohaline Circulation

- by Martin Sharp
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- Cartography, Glaciology, Synthetic Aperture Radar, Iceberg

Visible and infrared satellite images reveal numerous lineations on the Siple Coast region of West Antarctica. We used 5 MHz ice-penetrating radar to probe the interior and the bed of the ice sheet beneath a lineation at the boundary between Engelhardt Ice Ridge and flat-ice terrain to the south of the Kamb Ice Stream (KIS) outlet. Results show curved reflectors that emerge from the bed beneath 600 m thick ice. The tops of the reflectors extend about 100m into the ice above the bed, where they become almost horizontal. Apparent reflectivity of the horizontal section is about 20 dB less than that of the bed. We conclude that the likely cause of such strong reflection is sea water that was accreted into basal crevasses when the flat-ice terrain was floating. Internal layers are warped downward just downslope from the basal reflectors. It is thought that the downwarping was caused by localized basal melting in the past. The spatial pattern of downwarping suggests that localized basal m...

- by Howard Conway
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- Geophysics, Atmospheric sciences, Chronology, Fusion
- by E. Douglas Nilsson
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- Heat Transfer, Multidisciplinary, Energy Balance, Fusion
- by Hester Jiskoot
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- Remote Sensing, Image Analysis, Comparative Study, Multidisciplinary
- by Daniela Accettella
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- Earth Sciences, Climate Change, Marine Geology, Climate variability

- by David Burgess
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- Cartography, Glaciology, Synthetic Aperture Radar, Iceberg
- by David Burgess
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- Cartography, Glaciology, Synthetic Aperture Radar, Iceberg
- by Martin Siegert
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- Glaciology, Sea Level, Topography, Glaciers