Feedbacks between coupled subglacial hydrology and glacier dynamics

Hoffman, Matthew J.; Price, Stephen

doi:10.1002/2013jf002943

Cited by 85 publications

(142 citation statements)

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“…A subglacial hydrological model could be run for an entire year and basal parameters determined from an annual average water pressure. A key difficulty is running the hydrological model during the summer, as the development of the system is known to depend on feedbacks with velocity (Hoffman and Price, 2014). This issue can be avoided by using velocity measurements from remote sensing as a model forcing (e.g Fahnestock et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

“…These models have shown success in recreating the broad pattern of subglacial development in the summer melt season inferred from GPS measurements (Bartholomew et al, 2011;van de Wal et al, 2015) and dye-tracing experiments Cowton et al, 2013). The development of the subglacial hydrological system has been shown to depend on feedbacks from ice velocities (Hoffman and Price, 2014). However, applications of recent hydrology models coupled with iceflow models have been limited to idealized domains (Hewitt, 2013;Hoffman and Price, 2014;Hoffman et al, 2016;.…”

Section: Introductionmentioning

confidence: 99%

“…The development of the subglacial hydrological system has been shown to depend on feedbacks from ice velocities (Hoffman and Price, 2014). However, applications of recent hydrology models coupled with iceflow models have been limited to idealized domains (Hewitt, 2013;Hoffman and Price, 2014;Hoffman et al, 2016;.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Incorporating modelled subglacial hydrology into inversions for basal drag

Koziol

Arnold²

2017

The Cryosphere

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Abstract. A key challenge in modelling coupled ice-flowsubglacial hydrology is initializing the state and parameters of the system. We address this problem by presenting a workflow for initializing these values at the start of a summer melt season. The workflow depends on running a subglacial hydrology model for the winter season, when the system is not forced by meltwater inputs, and ice velocities can be assumed constant. Key parameters of the winter run of the subglacial hydrology model are determined from an initial inversion for basal drag using a linear sliding law. The state of the subglacial hydrology model at the end of winter is incorporated into an inversion of basal drag using a non-linear sliding law which is a function of water pressure. We demonstrate this procedure in the Russell Glacier area and compare the output of the linear sliding law with two non-linear sliding laws. Additionally, we compare the modelled winter hydrological state to radar observations and find that it is in line with summer rather than winter observations.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Incorporating modelled subglacial hydrology into inversions for basal drag

Koziol

Arnold²

2017

The Cryosphere

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“…The long-term implications of increased melting during warmer years, such as that witnessed in 2010 and 2012 , on subglacial drainage configuration, basal water pressure, and consequently ice dynamics, are difficult to assess without coupling a model such as the one presented here to subglacial drainage and ice flow models (e.g. Hewitt, 2013;de Fleurian et al, 2014;Hoffman and Price, 2014).…”

Section: C Clason Et Al: Modelling the Transfer Of Supraglacial mentioning

confidence: 99%

Modelling the transfer of supraglacial meltwater to the bed of Leverett Glacier, Southwest Greenland

et al. 2015

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Abstract. Meltwater delivered to the bed of the GreenlandIce Sheet is a driver of variable ice-motion through changes in effective pressure and enhanced basal lubrication. Ice surface velocities have been shown to respond rapidly both to meltwater production at the surface and to drainage of supraglacial lakes, suggesting efficient transfer of meltwater from the supraglacial to subglacial hydrological systems. Although considerable effort is currently being directed towards improved modelling of the controlling surface and basal processes, modelling the temporal and spatial evolution of the transfer of melt to the bed has received less attention. Here we present the results of spatially distributed modelling for prediction of moulins and lake drainages on the Leverett Glacier in Southwest Greenland. The model is run for the 2009 and 2010 ablation seasons, and for future increased melt scenarios. The temporal pattern of modelled lake drainages are qualitatively comparable with those documented from analyses of repeat satellite imagery. The modelled timings and locations of delivery of meltwater to the bed also match well with observed temporal and spatial patterns of ice surface speed-ups. This is particularly true for the lower catchment ( < 1000 m a.s.l.) where both the model and observations indicate that the development of moulins is the main mechanism for the transfer of surface meltwater to the bed. At higher elevations (e.g. 1250-1500 m a.s.l.) the development and drainage of supraglacial lakes becomes increasingly important. At these higher elevations, the delay between modelled melt generation and subsequent delivery of melt to the bed matches the observed delay between the peak air temperatures and subsequent velocity speed-ups, while the instantaneous transfer of melt to the bed in a control simulation does not. Although both moulins and lake drainages are predicted to increase in number for future warmer climate scenarios, the lake drainages play an increasingly important role in both expanding the area over which melt accesses the bed and in enabling a greater proportion of surface melt to reach the bed.

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“…Recent subglacial hydrology models have progressed to simultaneously incorporating both distributed and efficient systems, explicitly treating the interaction between the two (Hoffman and Price, 2014;de Fleurian et al, 2016;Hewitt, 2013;Pimentel and Flowers, 2010;Schoof, 2010;Werder et al, 2013). Current models can reproduce the observed up-glacier development of the efficient system through the melt season.…”

Section: Introductionmentioning

confidence: 99%

Modelling seasonal meltwater forcing of the velocity of land-terminating margins of the Greenland Ice Sheet

Koziol

Arnold²

2018

The Cryosphere

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Abstract. Surface runoff at the margin of the Greenland Ice Sheet (GrIS) drains to the ice-sheet bed, leading to enhanced summer ice flow. Ice velocities show a pattern of early summer acceleration followed by mid-summer deceleration due to evolution of the subglacial hydrology system in response to meltwater forcing. Modelling the integrated hydrologicalice dynamics system to reproduce measured velocities at the ice margin remains a key challenge for validating the present understanding of the system and constraining the impact of increasing surface runoff rates on dynamic ice mass loss from the GrIS. Here we show that a multi-component model incorporating supraglacial, subglacial, and ice dynamic components applied to a land-terminating catchment in western Greenland produces modelled velocities which are in reasonable agreement with those observed in GPS records for three melt seasons of varying melt intensities. This provides numerical support for the hypothesis that the subglacial system develops analogously to alpine glaciers and supports recent model formulations capturing the transition between distributed and channelized states. The model shows the growth of efficient conduit-based drainage up-glacier from the ice sheet margin, which develops more extensively, and further inland, as melt intensity increases. This suggests current trends of decadal-timescale slowdown of ice velocities in the ablation zone may continue in the near future. The model results also show a strong scaling between average summer velocities and melt season intensity, particularly in the upper ablation area. Assuming winter velocities are not impacted by channelization, our model suggests an upper bound of a 25 % increase in annual surface velocities as surface melt increases to 4× present levels.

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Feedbacks between coupled subglacial hydrology and glacier dynamics

Cited by 85 publications

References 85 publications

Incorporating modelled subglacial hydrology into inversions for basal drag

Incorporating modelled subglacial hydrology into inversions for basal drag

Modelling the transfer of supraglacial meltwater to the bed of Leverett Glacier, Southwest Greenland

Modelling seasonal meltwater forcing of the velocity of land-terminating margins of the Greenland Ice Sheet

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