Mass-conserving subglacial hydrology in the Parallel Ice Sheet Model version 0.6

Bueler, Ed; Pelt, Ward van

doi:10.5194/gmd-8-1613-2015

Cited by 126 publications

(215 citation statements)

References 64 publications

(143 reference statements)

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“…(12) is due to Bueler and van Pelt (2015) by considering a hydrological model of subglacial water drainage within the till. However, Martin et al (2011) propose to relate major till characteristics to bedrock geometry and allow till friction angle and basal water pressure to be a function of the bed elevation compared to sea level.…”

Section: Coulomb Friction Lawmentioning

confidence: 99%

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Sea-level response to melting of Antarctic ice shelves on multi-centennial timescales with the fast Elementary Thermomechanical Ice Sheet model (f.ETISh v1.0)

2017

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Abstract. The magnitude of the Antarctic ice sheet's contribution to global sea-level rise is dominated by the potential of its marine sectors to become unstable and collapse as a response to ocean (and atmospheric) forcing. This paper presents Antarctic sea-level response to sudden atmospheric and oceanic forcings on multi-centennial timescales with the newly developed fast Elementary Thermomechanical Ice Sheet (f.ETISh) model. The f.ETISh model is a vertically integrated hybrid ice sheet-ice shelf model with vertically integrated thermomechanical coupling, making the model twodimensional. Its marine boundary is represented by two different flux conditions, coherent with power-law basal sliding and Coulomb basal friction. The model has been compared to existing benchmarks.Modelled Antarctic ice sheet response to forcing is dominated by sub-ice shelf melt and the sensitivity is highly dependent on basal conditions at the grounding line. Coulomb friction in the grounding-line transition zone leads to significantly higher mass loss in both West and East Antarctica on centennial timescales, leading to 1.5 m sea-level rise after 500 years for a limited melt scenario of 10 m a −1 under freely floating ice shelves, up to 6 m for a 50 m a −1 scenario. The higher sensitivity is attributed to higher ice fluxes at the grounding line due to vanishing effective pressure.Removing the ice shelves altogether results in a disintegration of the West Antarctic ice sheet and (partially) marine basins in East Antarctica. After 500 years, this leads to a 5 m and a 16 m sea-level rise for the power-law basal sliding and Coulomb friction conditions at the grounding line, respectively. The latter value agrees with simulations by DeConto and Pollard (2016) over a similar period (but with different forcing and including processes of hydrofracturing and cliff failure).The chosen parametrizations make model results largely independent of spatial resolution so that f.ETISh can potentially be integrated in large-scale Earth system models.

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Section: Coulomb Friction Lawmentioning

confidence: 99%

“…(14). To link Coulomb friction to basal drag, the formulation proposed by Bueler and van Pelt (2015) is opted for, where τ c and v b combine to determine τ b through a sliding law, i.e.…”

Section: Coulomb Friction Lawmentioning

confidence: 99%

Sea-level response to melting of Antarctic ice shelves on multi-centennial timescales with the fast Elementary Thermomechanical Ice Sheet model (f.ETISh v1.0)

2017

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“…The result from PISM shows distinct branches for the different glaciers, which display a relatively 20 sharp separation from the surrounding area. Note, that PISM also uses a basal hydrology model as described in Bueler and van Pelt (2015). Velocities are slightly lower than observed velocities, especially for Zacharias Isbrae and in the area, where ZI and 79NG are closest.…”

mentioning

confidence: 99%

A confined–unconfined aquifer model for subglacial hydrology and its application to the North East Greenland Ice Stream

Beyer¹,

Kleiner²,

Aizinger³

et al. 2017

Preprint

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Abstract. Subglacial hydrology plays an important role in the ice sheet dynamics as it determines the sliding velocity of ice sheets and also drives freshwater into the ocean. Modeling subglacial water has been a challenge for decades, and only recently new approaches have been developed such as representing subglacial channels and thin water sheets by separate layers of variable permeability. We extend this concept by modeling a confined and unconfined aquifer system (CUAS) in a single layer. The advantage of this formulation is that it prevents unphysical values of pressure at reasonable computational 5 cost. We also performed sensitivity tests to investigate the effect of different model parameters. The strongest influence of model parameters was detected in terms governing the opening and closure of channels. Furthermore, we applied the model to the North East Greenland Ice Stream, where an efficient system independent of seasonal input was identified about 500 km downstream from the ice divide. Using the effective pressure from the hydrology model in the Ice Sheet System Model (ISSM) shows considerable improvements of modeled velocities in the coastal region.

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“…Here τ c is the till yield stress (Bueler and van Pelt, 2015), which evolves in time with changing basal till water content and overburden pressure (see below). For simplicity we set the velocity scaling parameter u 0 to 1 m s −1 (unit of the sliding velocity calculated in the model, as chosen in, e.g., Pattyn et al, 2013;Feldmann et al, 2014;Feldmann and Levermann, 2015a).…”

Section: Modelmentioning

confidence: 99%

From cyclic ice streaming to Heinrich-like events: the grow-and-surge instability in the Parallel Ice Sheet Model

Feldmann

Levermann

2017

The Cryosphere

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Abstract. Here we report on a cyclic, physical ice-discharge instability in the Parallel Ice Sheet Model, simulating the flow of a three-dimensional, inherently buttressed ice-sheetshelf system which periodically surges on a millennial timescale. The thermomechanically coupled model on 1 km horizontal resolution includes an enthalpy-based formulation of the thermodynamics, a nonlinear stress-balance-based sliding law and a very simple subglacial hydrology. The simulated unforced surging is characterized by rapid ice streaming through a bed trough, resulting in abrupt discharge of ice across the grounding line which is eventually calved into the ocean. We visualize the central feedbacks that dominate the subsequent phases of ice buildup, surge and stabilization which emerge from the interaction between ice dynamics, thermodynamics and the subglacial till layer. Results from the variation of surface mass balance and basal roughness suggest that ice sheets of medium thickness may be more susceptible to surging than relatively thin or thick ones for which the surge feedback loop is damped. We also investigate the influence of different basal sliding laws (ranging from purely plastic to nonlinear to linear) on possible surging. The presented mechanisms underlying our simulations of self-maintained, periodic ice growth and destabilization may play a role in large-scale ice-sheet surging, such as the surging of the Laurentide Ice Sheet, which is associated with Heinrich events, and ice-stream shutdown and reactivation, such as observed in the Siple Coast region of West Antarctica.

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Mass-conserving subglacial hydrology in the Parallel Ice Sheet Model version 0.6

Cited by 126 publications

References 64 publications

Sea-level response to melting of Antarctic ice shelves on multi-centennial timescales with the fast Elementary Thermomechanical Ice Sheet model (f.ETISh v1.0)

Sea-level response to melting of Antarctic ice shelves on multi-centennial timescales with the fast Elementary Thermomechanical Ice Sheet model (f.ETISh v1.0)

A confined–unconfined aquifer model for subglacial hydrology and its application to the North East Greenland Ice Stream

From cyclic ice streaming to Heinrich-like events: the grow-and-surge instability in the Parallel Ice Sheet Model

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