A Three-Dimensional Time-Dependent Model of the West Antarctic Ice Sheet

Budd, W. F.; Jenssen, D.; Smith, Ian

doi:10.3189/1984aog5-1-29-36

Cited by 66 publications

(70 citation statements)

References 30 publications

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“…These enhanced flow features have a low basal shear stress, causing surface drawdown and strongly concave plan contours (Figure 2e, numerical model result where basal sliding is a function of both the basal shear stress and the effective pressure [e.g., Budd et al, 1984]), and, hence, strongly concave PC values (Figure 2f). Interstream ridges, flowing by internal deformation only, will form between the fast flow features where relative bed elevations tend to be higher (cf.…”

Section: Plan Curvaturementioning

confidence: 99%

Subglacial topography inferred from ice surface terrain analysis reveals a large un‐surveyed basin below sea level in East Antarctica

Brocq¹,

Hubbard²,

Bentley³

et al. 2008

Geophysical Research Letters

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Section: Plan Curvaturementioning

confidence: 99%

Subglacial topography inferred from ice surface terrain analysis reveals a large un‐surveyed basin below sea level in East Antarctica

Brocq¹,

Hubbard²,

Bentley³

et al. 2008

Geophysical Research Letters

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“…Note that we have f ∼ 90 % at the borehole, in agreement with the measurements. At the glacier bed, we apply Budd's friction law (Budd et al, 1984), which links basal shear stress (τ b ) to basal sliding (u b ) through the relation…”

Section: Modellingmentioning

confidence: 99%

Initiation of a major calving event on the Bowdoin Glacier captured by UAV photogrammetry

Jouvet¹,

Weidmann²,

Seguinot³

et al. 2017

The Cryosphere

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Abstract. In this paper, we analyse the calving activity of the Bowdoin Glacier, north-western Greenland, in 2015 by combining satellite images, UAV (unmanned aerial vehicle) photogrammetry and ice flow modelling. In particular, a highresolution displacement field is inferred from UAV orthoimages taken immediately before and after the initiation of a large fracture, which induced a major calving event. A detailed analysis of the strain rate field allows us to accurately map the path taken by the opening crack. Modelling results reveal (i) that the crack was more than half-thickness deep, filled with water and getting irreversibly deeper when it was captured by the UAV and (ii) that the crack initiated in an area of high horizontal shear caused by a local basal bump immediately behind the current calving front. The asymmetry of the bed at the front explains the systematic calving pattern observed in May and July-August 2015. As a corollary, we infer that the calving front of the Bowdoin Glacier is currently stabilized by this bedrock bump and might enter into an unstable mode and retreat rapidly if the glacier keeps thinning in the coming years. Beyond this outcome, our study demonstrates that the combination of UAV photogrammetry and ice flow modelling is a promising tool to horizontally and vertically track the propagation of fractures responsible for large calving events.

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“…Various parameterisations were developed from the information about velocities, surface slopes and ice thicknesses available then (see e.g. Budd et al, 1984, and references therein).…”

Section: Basal Slidingmentioning

confidence: 99%

“…This was proposed over 30 years ago (e.g. Budd et al, 1984) and may affect the resolution requirements for successful grounding line modelling. Recent treatments of basal traction that also vanish smoothly at the grounding line include Leguy et al (2014) and Tsai et al (2015).…”

Section: Introductionmentioning

confidence: 99%

Marine ice sheet model performance depends on basal sliding physics and sub-shelf melting

et al. 2017

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Abstract. Computer models are necessary for understanding and predicting marine ice sheet behaviour. However, there is uncertainty over implementation of physical processes at the ice base, both for grounded and floating glacial ice. Here we implement several sliding relations in a marine ice sheet flow-line model accounting for all stress components and demonstrate that model resolution requirements are strongly dependent on both the choice of basal sliding relation and the spatial distribution of ice shelf basal melting.Sliding relations that reduce the magnitude of the step change in basal drag from grounded ice to floating ice (where basal drag is set to zero) show reduced dependence on resolution compared to a commonly used relation, in which basal drag is purely a power law function of basal ice velocity. Sliding relations in which basal drag goes smoothly to zero as the grounding line is approached from inland (due to a physically motivated incorporation of effective pressure at the bed) provide further reduction in resolution dependence.A similar issue is found with the imposition of basal melt under the floating part of the ice shelf: melt parameterisations that reduce the abruptness of change in basal melting from grounded ice (where basal melt is set to zero) to floating ice provide improved convergence with resolution compared to parameterisations in which high melt occurs adjacent to the grounding line.Thus physical processes, such as sub-glacial outflow (which could cause high melt near the grounding line), impact on capability to simulate marine ice sheets. If there exists an abrupt change across the grounding line in either basal drag or basal melting, then high resolution will be required to solve the problem. However, the plausible combination of a physical dependency of basal drag on effective pressure, and the possibility of low ice shelf basal melt rates next to the grounding line, may mean that some marine ice sheet systems can be reliably simulated at a coarser resolution than currently thought necessary.

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A Three-Dimensional Time-Dependent Model of the West Antarctic Ice Sheet

Cited by 66 publications

References 30 publications

Subglacial topography inferred from ice surface terrain analysis reveals a large un‐surveyed basin below sea level in East Antarctica

Subglacial topography inferred from ice surface terrain analysis reveals a large un‐surveyed basin below sea level in East Antarctica

Initiation of a major calving event on the Bowdoin Glacier captured by UAV photogrammetry

Marine ice sheet model performance depends on basal sliding physics and sub-shelf melting

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