A numerical study of glacier advance over deforming till

Vieli, Gwendolyn J.-M. C. Leysinger; Gudmundsson, G. Hilmar

doi:10.5194/tc-4-359-2010

Cited by 20 publications

(9 citation statements)

References 56 publications

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“…The till was modelled as viscous medium using a flow law of the same form as GlenSteinemann constitutive law. This approach of introducing basal motion has been used in numerous numerical studies, and a recent example for this approach with detailed description can be found in Leysinger Vieli and Gudmundsson (2010).…”

Section: Basal Boundary Conditionmentioning

confidence: 99%

Ice-stream response to ocean tides and the form of the basal sliding law

2011

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Abstract. The response of ice streams to ocean tides is investigated. Numerical modelling experiments are conducted using a two-dimensional flow-line model of coupled ice-stream and ice-shelf flow. The model includes all components of the equilibrium equations, and uses a non-linear viscoelastic constitutive equation for ice. Basal sliding is simulated with a Weertman type sliding law where basal sliding is proportional to some power of the basal shear stress. The response of ice-streams to tidal forcing is found to be profoundly affected by mechanical conditions at the bed. For a non-linear sliding law, a non-linear interaction between the two main semi-diurnal tidal constituents (M2 and S2) can give rise to a significant perturbation in ice-stream flow at the lunisolar synodic fortnightly (MSf) tidal period of 14.76 days. For a linear sliding law, in contrast, no such modulation in flow at the MSf frequency is found. For vertical ocean tides of the type observed on Filchner-Ronne Ice Shelf (FRIS), the amplitude of the horizontal modulation in ice-stream flow at the MSf frequency resulting from a non-linear interaction between the S2 and M2 tidal constitutes can be larger than the direct response at the S2 and the M2 frequencies. In comparison the non-linear interaction between K1 and O1 tidal components is weak. As a consequence, modelled icestream response to mixed oceanic tides of the type found on FRIS is stronger at the MSf period of 14.76 days than at both the semi-diurnal and diurnal frequencies, while at the same time almost absent at the similar Mf period of 13.66 days. The model results compare favourably with measurements of tidally induced flow variations on Rutford Ice Stream (RIS), West Antarctica. On RIS a strong tidal response is found at the MSf frequency with a smaller response at the semidiurnal and diurnal frequencies, and almost no response at the Mf frequency. A non-linear viscous sliding law appears to have the potential to fully explain these observations.

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Section: Basal Boundary Conditionmentioning

confidence: 99%

Ice-stream response to ocean tides and the form of the basal sliding law

2011

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“…Stimulated by Haeberli, expertise was combined between the disciplines of geotechnics (Arenson 2002), geophysics (Musil 2002; Maurer et al . 2010) and glaciology (Leysinger Vieli 2003) to investigate the Muragl rock glacier in the Engadine in the Swiss Alps (Fig. 1) as the first of two ETH‐funded multi‐investigator projects to promote better process understanding, to lead to more effective future modelling and prediction of behaviour.…”

Section: Introductionmentioning

confidence: 99%

Multidisciplinary investigations on three rock glaciers in the swiss alps: legacies and future perspectives

Springman¹,

Arenson

Yamamoto³

et al. 2012

Geografiska Annaler: Series A, Physical Geography

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This paper recognizes the contribution of Professor Wilfried Haeberli for his inspiration and leadership in the field of permafrost science and his generous encouragement, both direct and indirect, to the ETH Researchers who have, through him, endeavoured to contribute to this fascinating research area. The multidisciplinary investigations described in this paper have focused on three rock glaciers, Muragl, Murtèl‐Corvatsch and Furggwanghorn, all of which have been subject to a varying degree of prior study, and which are continuing to attract new generations of researchers to understand and explain the processes and predict future behaviour. This paper marks a stage at which it is possible to summarize some advances in the state of the art and associated innovations that can be attributed to early motivation by Wilfried Haeberli and offers a tribute as well as gratitude for his ongoing feedback and advice. Some thoughts on the development of thermokarst due to water ponding and flow, and a conceptual model of geotechnical mechanisms that aim to explain some aspects of rock glacier kinematics, are also introduced.

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“…The 2000s in Svalbard were likely warmer than any period in the previous 1000 yr (Grinsted et al, 2006;Virkkunen et al, 2007;Divine et al, 2011). Dunse et al (2009) identify a high amount of surface melt over the southern part of ASF in summer 2004, followed by lowering of the firn line and increase in SMB until 2007 (see also Moholdt et al (2010)).…”

Section: Discussionmentioning

confidence: 97%

Importance of basal processes in simulations of a surging Svalbard outlet glacier

Gladstone¹,

Schäfer²,

Zwinger³

et al. 2013

Preprint

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Abstract. The outlet glacier of Basin 3 (B3) of Austfonna icecap, Svalbard, is one of the fastest outlet glaciers in Svalbard, and shows dramatic changes since 1995. In addition to previously observed seasonal summer speed up associated with the melt season, the winter speed of B3 has accelerated approximately five fold since 1995. We use the Elmer/Ice full Stokes model for ice dynamics to infer spatial distributions of basal drag for the winter seasons of 1995, 2008 and 2011. This "inverse" method is based on minimising discrepancy between modelled and observed surface velocities, using satellite remotely sensed velocity fields. We generate steady state temperature distributions for the three time periods. Frictional heating caused by basal sliding contributes significantly to basal temperatures of the B3 outlet glacier, which exhibits a uniform steady state basal temperature at pressure melting point in all three cases. We present a sensitivity experiment consisting of transient simulations under present day forcing to demonstrate that using a temporally fixed basal drag field obtained through inversion can lead to thickness change errors of the order of 2 m per year. Hence it is essential to incorporate the evolution of basal processes in future projections of the basin. Informed by a combination of our inverse method results and previous studies, we hypothesize a system of processes and feedbacks involving till deformation and basal hydrology to explain both the seasonal accelerations and the ongoing inter-annual speed up, and speculate on the wider relevance of deformable till mechanics to non-surging glaciers.

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A numerical study of glacier advance over deforming till

Cited by 20 publications

References 56 publications

Ice-stream response to ocean tides and the form of the basal sliding law

Ice-stream response to ocean tides and the form of the basal sliding law

Multidisciplinary investigations on three rock glaciers in the swiss alps: legacies and future perspectives

Importance of basal processes in simulations of a surging Svalbard outlet glacier

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