Search

Search Results

• 1. [Article] Tributaries to West Antarctic ice Streams: Characteristics Deduced from Numerical Modelling of Ice Flow

  A network of relatively fast-flowing tributaries in the catchment basins of the West Antarctic ice streams transport ice from the inland reservoir to the heads of the ice streams. Branches of the network ...

  Citation × Citation Citation Abstract Copy Title: Tributaries to West Antarctic ice Streams: Characteristics Deduced from Numerical Modelling of Ice Flow Author: Hulbe, Christina L., Joughin, Ian R., Morse, David L., Bindschadler, R. A. Year: 2000 A network of relatively fast-flowing tributaries in the catchment basins of the West Antarctic ice streams transport ice from the inland reservoir to the heads of the ice streams. Branches of the network follow valleys in basal topography, but not all valleys contain tributaries. We investigate the circumstances favoring tributary flow upstream of Ice Streams D and E, using a combination of observation and numerical modelling. No consistent pattern emerges. The transition from tributary to ice-stream flow occurs smoothly along the main tributary feeding into the onset of Ice Stream D, with ice thickness being relatively more important upstream, and sliding being relatively more important downstream. Elsewhere, the downstream pattern of flow is more complicated, with local increases and decreases in the contribution of sliding to ice speed. Those changes may be due to variations in basal water storage, subglacial geologic properties or a combination of the two. Title: Tributaries to West Antarctic ice Streams: Characteristics Deduced from Numerical Modelling of Ice Flow Author: Hulbe, Christina L., Joughin, Ian R., Morse, David L., Bindschadler, R. A. Year: 2000 A network of relatively fast-flowing tributaries in the catchment basins of the West Antarctic ice streams transport ice from the inland reservoir to the heads of the ice streams. Branches of the network follow valleys in basal topography, but not all valleys contain tributaries. We investigate the circumstances favoring tributary flow upstream of Ice Streams D and E, using a combination of observation and numerical modelling. No consistent pattern emerges. The transition from tributary to ice-stream flow occurs smoothly along the main tributary feeding into the onset of Ice Stream D, with ice thickness being relatively more important upstream, and sliding being relatively more important downstream. Elsewhere, the downstream pattern of flow is more complicated, with local increases and decreases in the contribution of sliding to ice speed. Those changes may be due to variations in basal water storage, subglacial geologic properties or a combination of the two. Close

• 2. [Article] Post-Stagnation Behavior in the Upstream Regions of Ice Stream C, West Antarctica

  The region where two active tributaries feed into the now stagnant Ice Stream C (ISC), West Antarctica, is thickening. In this region, we observe a correlation between faster ice flow (the tributaries) ...

  Citation × Citation Citation Abstract Copy Title: Post-Stagnation Behavior in the Upstream Regions of Ice Stream C, West Antarctica Author: Price, Stephen F., Bindschadler, R. A., Hulbe, Christina L., Joughin, Ian R. Year: 2001 The region where two active tributaries feed into the now stagnant Ice Stream C (ISC), West Antarctica, is thickening. In this region, we observe a correlation between faster ice flow (the tributaries) and elevated topography. We conclude that stagnation of ISC resulted in compression and thickening along the tributaries, eventually forming a "bulge" on the ice-sheet surface. Modern hydraulic potential gradients would divert basal meltwater from ISC to Ice Stream B (ISB). These gradients are primarily controlled by the bulge topography, and so likely formed subsequent to trunk stagnation. As such, we argue against "water piracy" as being the cause for ISC's stagnation. Kinematic-wave theory suggests that thickness perturbations propagate downstream over time, but that kinematic-wave speed decreases near the stagnant trunk. This and modest diffusion rates combine to trap most of the tributary-fed ice in the bulge region. Using interferometric synthetic aperture radar velocity measurements, we observe that half of the ice within ISC's southern tributary flows into ISB. That flow pattern and other observations of non-steady flow in the region likely result from stagnation-induced thickening along upper ISC combined with a longer period of thinning on upper ISB. If current trends in thickness change continue, more ice from upper ISC will be diverted to ISB. Title: Post-Stagnation Behavior in the Upstream Regions of Ice Stream C, West Antarctica Author: Price, Stephen F., Bindschadler, R. A., Hulbe, Christina L., Joughin, Ian R. Year: 2001 The region where two active tributaries feed into the now stagnant Ice Stream C (ISC), West Antarctica, is thickening. In this region, we observe a correlation between faster ice flow (the tributaries) and elevated topography. We conclude that stagnation of ISC resulted in compression and thickening along the tributaries, eventually forming a "bulge" on the ice-sheet surface. Modern hydraulic potential gradients would divert basal meltwater from ISC to Ice Stream B (ISB). These gradients are primarily controlled by the bulge topography, and so likely formed subsequent to trunk stagnation. As such, we argue against "water piracy" as being the cause for ISC's stagnation. Kinematic-wave theory suggests that thickness perturbations propagate downstream over time, but that kinematic-wave speed decreases near the stagnant trunk. This and modest diffusion rates combine to trap most of the tributary-fed ice in the bulge region. Using interferometric synthetic aperture radar velocity measurements, we observe that half of the ice within ISC's southern tributary flows into ISB. That flow pattern and other observations of non-steady flow in the region likely result from stagnation-induced thickening along upper ISC combined with a longer period of thinning on upper ISB. If current trends in thickness change continue, more ice from upper ISC will be diverted to ISB. Close