Simulated melt rates for the Totten and Dalton ice shelves

Gwyther, David; Galton-Fenzi, B; Hunter, John; Roberts, Jason L.

doi:10.5194/os-10-267-2014

Cited by 84 publications

(115 citation statements)

References 62 publications

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“…The model includes ocean-ice shelf thermodynamics described by three equations following Holland and Jenkins (1999), frazil ice thermodynamics following Galton-Fenzi et al (2012), as used in previous studies (e.g., Cougnon et al, 2013;Gwyther et al, 2014) and a simplified analytic tidal forcing at the lateral boundaries (Cougnon et al, 2017 for details). The bathymetry in both simulations is based on RTopo-1 (Timmermann et al, 2010), and modified to include local high-resolution bathymetry as described in Mayet et al (2013).…”

Section: Environmental Data and Numerical Modeling Ocean Model And Bamentioning

confidence: 99%

Mapping Antarctic Suspension Feeder Abundances and Seafloor Food-Availability, and Modeling Their Change After a Major Glacier Calving

et al. 2018

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Seafloor communities are a critical part of the unique and diverse Antarctic marine life. Processes at the ocean-surface can strongly influence the diversity and abundance of these communities, even when they live at hundreds of meters water depth. However, even though we understand the importance of this link, there are so far no quantitative spatial predictions on how seafloor communities will respond to changing conditions at the ocean surface. Here, we map patterns in abundance of important habitat-forming suspension feeders on the seafloor in East Antarctica, and predict how these patterns change after a major disturbance in the icescape, caused by the calving of the Mertz Glacier Tongue. We use a purpose-built ocean model for the time-period before and after the calving of the Mertz-Glacier Tongue in 2010, data from satellites and a validated food-availability model to estimate changes in horizontal flux of food since the glacier calving. We then predict the post-calving distribution of suspension feeder abundances using the established relationships with the environmental variables, and changes in horizontal flux of food. Our resulting maps indicate strong increases in suspension feeder abundances close to the glacier calving site, fueled by increased food supply, while the remainder of the region maintains similar suspension feeder abundances despite a slight decrease in total food supply. The oceanographic setting of the entire region changes, with a shorter ice-free season, altered seafloor currents and changes in food-availability. Our study provides important insight into the flow-on effects of a changing icescape on seafloor habitat and fauna in polar environments. Understanding these connections is important in the context of current and future effects of climate change, and the mapped predictions of the seafloor fauna as presented for the study region can be used as a decision-tool for planning potential marine protected areas, and for focusing future sampling and monitoring initiatives.

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Section: Environmental Data and Numerical Modeling Ocean Model And Bamentioning

confidence: 99%

Mapping Antarctic Suspension Feeder Abundances and Seafloor Food-Availability, and Modeling Their Change After a Major Glacier Calving

et al. 2018

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“…Numerical ocean modelling indicates that interannual differences in water mass properties in the region can lead to large variations in basal melting of the TIS (Khazendar et al 2013;Gwyther et al 2014), suggesting that both TIS elevations and ice dynamics may be modulated by variability in ocean forcing (Li et al 2016). Thus, the aim of this paper is to provide a mechanism which explains that the variability of the TIS is in response to changes in ocean forcing.…”

mentioning

confidence: 99%

Ocean forced variability of Totten Glacier mass loss

Roberts

Galton-Fenzi

Paolo

et al. 2017

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Abstract: A large volume of the East Antarctic Ice Sheet drains through the Totten Glacier (TG) and is thought to be a potential source of substantial global sea-level rise over the coming centuries. We show that the surface velocity and height of the floating part of the TG, which buttresses the grounded component, have varied substantially over two decades , with variations in surface height strongly anti-correlated with simulated basal melt rates (r = 0.70, p < 0.05). Coupled glacier-ice shelf simulations confirm that ice flow and thickness respond to both basal melting of the ice shelf and grounding on bed obstacles. We conclude the observed variability of the TG is primarily ocean-driven. Ocean warming in this region will lead to enhanced ice-sheet dynamism and loss of upstream grounded ice.

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“…been suggested by Bassis and Ma (2015). Basal melt rates are highest at the southern end of the Totten Ice Shelf (Gwyther et al, 2014) where the thicker ice shelf means that the pressure dependent melting point is reduced at the base. Nearer the calving front, accelerating velocities and lateral spreading of the ice means internal deformation is more likely to be a dominant factor in basal crevasse evolution (e.g.…”

Section: Fracture Advectionmentioning

confidence: 99%

“…The evolution of basal fractures predicted here by the KPZ equation neglects spatial variations in melt rate across the ice shelf (e. g. Gwyther et al, 2014;Roberts et al, 2017), as well as variations in melt rate which have been predicted to occur within 15 basal features (Jordan et al, 2014;Millgate et al, 2013). It also does not include the effects of internal ice deformation and strain thinning, which are particularly significant near the calving front where the ice shelf is unconfined and spreads laterally.…”

Section: Fracture Advectionmentioning

confidence: 99%

“…The glacier flow rate accelerates downstream of the grounding area, meaning the ice will stretch and thin, causing the basal cracks to widen as they move downstream. The water in the ocean cavity underneath the Totten IS is also known to be warm enough to drive melt of the ice (Gwyther et al, 2014;Rintoul et al, 2016;Roberts et al, 2017). As basal crevasses 5 are exposed to sea water one might also expect that the cracks will become wider and deeper by melting.…”

Section: Fracture Advectionmentioning

confidence: 99%

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Modelled fracture and calving on the Totten Ice Shelf

Cook¹,

Åström²,

Zwinger³

et al. 2018

Preprint

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Abstract. The Totten Ice Shelf (IS) has a large drainage basin, much of which is grounded below sea level, leaving the glacier vulnerable to retreat through the Marine Ice Shelf Instability mechanism. The ice shelf has also been shown to be sensitive to changes in calving rate, as a very small retreat of the calving front from its current position is predicted to cause a change in flow at the grounding line. Therefore understanding the processes behind calving on the Totten IS is key to predicting its future sea level rise contribution. Here we use the Helsinki Discrete Element Model (HiDEM) to show that calving on the Totten IS 15 is controlled not only by locally produced fractures at the calving front, but is also influenced by basal fractures which are likely produced at the grounding line. Our model results show that regrounding points may be key areas of basal crevasse production, and can produce basal crevasses in both an along and across flow orientation. As well as affecting calving, along flow basal crevasses at the grounding line may be a possible precursor to basal channels. We use two additional models to examine the evolution of basal fractures as they advect downstream, demonstrating that both strain and ocean melt have the 20 potential to deform narrow fractures into the broad basal features observed near the calving front. The wide range of factors which influence fracture patterns and calving on this glacier will be a challenge for predicting its future mass loss.

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Simulated melt rates for the Totten and Dalton ice shelves

Cited by 84 publications

References 62 publications

Mapping Antarctic Suspension Feeder Abundances and Seafloor Food-Availability, and Modeling Their Change After a Major Glacier Calving

Mapping Antarctic Suspension Feeder Abundances and Seafloor Food-Availability, and Modeling Their Change After a Major Glacier Calving

Ocean forced variability of Totten Glacier mass loss

Modelled fracture and calving on the Totten Ice Shelf

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