Subaqueous calving margin morphology at Mueller, Hooker and Tasman glaciers in Aoraki/Mount Cook National Park, New Zealand

Robertson, Clare; Benn, Douglas I.; Brook, Martin; Fuller, Ian C.; Holt, Kat

doi:10.3189/2012jog12j048

Cited by 32 publications

(52 citation statements)

References 36 publications

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“…The warmer water near the surface leads to higher melting rates in that region, resulting in submerged ice projecting beyond the subaerial face [Wright and Haynes, 1892;Savage, 2001;Stern et al, 2015]. Ice blocks have been found to surface 500 m from the terminus of LeConte Glacier in Alaska [Motyka, 1997], and submarine ice feet were recently observed to extend to similar distances at lake-terminating glaciers in New Zealand [Robertson et al, 2012]. Ice blocks have been found to surface 500 m from the terminus of LeConte Glacier in Alaska [Motyka, 1997], and submarine ice feet were recently observed to extend to similar distances at lake-terminating glaciers in New Zealand [Robertson et al, 2012].…”

Section: Introductionmentioning

confidence: 99%

On the role of buoyant flexure in glacier calving

Wagner

James

Murray

et al. 2016

Geophysical Research Letters

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Interactions between glaciers and the ocean are key for understanding the dynamics of the cryosphere in the climate system. Here we investigate the role of hydrostatic forces in glacier calving. We develop a mathematical model to account for the elastic deformation of glaciers in response to three effects: (i) marine and lake‐terminating glaciers tend to enter water with a nonzero slope, resulting in upward flexure around the grounding line; (ii) horizontal pressure imbalances at the terminus are known to cause hydrostatic in‐plane stresses and downward acting torque; (iii) submerged ice protrusions at the glacier front may induce additional buoyancy forces that can cause calving. Our model provides theoretical estimates of the importance of each effect and suggests geometric and material conditions under which a given glacier will calve from hydrostatic flexure. We find good agreement with observations. This work sheds light on the intricate processes involved in glacier calving and can be hoped to improve our ability to model and predict future changes in the ice‐climate system.

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Section: Introductionmentioning

confidence: 99%

On the role of buoyant flexure in glacier calving

Wagner

James

Murray

et al. 2016

Geophysical Research Letters

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“…Robertson et al (2012) found that ice ramps at the glacier end of glacial lakes tend to have slopes between 11 and 30 • and exhibit subaqueous calving. The level of knowledge of ice ramps in glacial lakes is limited, so it is difficult to determine ramp gradients exactly without detailed bathymetric information.…”

Section: Bathymetric Surveymentioning

confidence: 99%

“…The level of knowledge of ice ramps in glacial lakes is limited, so it is difficult to determine ramp gradients exactly without detailed bathymetric information. Rather than using the slopes from Robertson et al (2012), that are more applicable to the Tasman glacier area, the slopes have been changed to resemble the slopes measured at Imja Tsho in 1992 and 2002 by Sakai et al (2005). Figure 3 shows a longitudinal dashed line in the lake following the 1992 and 2002 transect from the western shoreline of the lake to the eastern shoreline reported by Sakai et al (2005).…”

Section: Bathymetric Surveymentioning

confidence: 99%

Changes in Imja Tsho in the Mount Everest region of Nepal

et al. 2014

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Abstract. Imja Tsho, located in the Sagarmatha (Everest) National Park of Nepal, is one of the most studied and rapidly growing lakes in the Himalayan range. Compared with previous studies, the results of our sonar bathymetric survey conducted in September of 2012 suggest that its maximum depth has increased from 90.5 to 116.3 ± 5.2 m since 2002, and that its estimated volume has grown from 35.8 ± 0.7 to 61.7 ± 3.7 million m 3 . Most of the expansion of the lake in recent years has taken place in the glacier terminus-lake interface on the eastern end of the lake, with the glacier receding at about 52 m yr −1 and the lake expanding in area by 0.04 km 2 yr −1 . A ground penetrating radar survey of the Imja-Lhotse Shar glacier just behind the glacier terminus shows that the ice is over 200 m thick in the center of the glacier. The volume of water that could be released from the lake in the event of a breach in the damming moraine on the western end of the lake has increased to 34.1 ± 1.08 million m 3 from the 21 million m 3 estimated in 2002.

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“…Bridge Lake, at 6.3 km 2 , is small relative to the much larger lakes of Southern Patagonia, while only marginally shallower. As such, many large Patagonian proglacial lakes contain vast areas that are free of the strong cooling influence of glacier runoff and trapped icebergs and can warm significantly, promoting thermal undercutting and enhancing further calving (Rohl, 2006;Rignot et al, 2010;Robertson et al, 2012).…”

Section: Locationmentioning

confidence: 99%

Ablation from calving and surface melt at lake-terminating Bridge Glacier, British Columbia, 1984–2013

Chernos¹,

Koppes²,

Moore³

2016

The Cryosphere

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Abstract. Bridge Glacier is a lake-calving glacier in the Coast Mountains of British Columbia and has retreated over 3.55 km since 1972. The majority of this retreat has occurred since 1991. This retreat is substantially greater than what has been inferred from regional climate indices, suggesting that it has been driven primarily by calving as the glacier retreated across an overdeepened basin. In order to better understand the primary drivers of ablation, surface melt (below the equilibrium line altitude, ELA) and calving were quantified during the 2013 melt season using a distributed energy balance model (DEBM) and time-lapse imagery. Calving, estimated using areal change, velocity measurements, and assuming flotation were responsible for 23 % of the glacier's ablation below the ELA during the 2013 melt season and were limited by modest flow speeds and a small terminus cross-section. Calving and surface melt estimates from 1984 to 2013 suggest that calving was consistently a smaller contributor of ablation. Although calving was estimated to be responsible for up to 49 % of the glacier's ablation for individual seasons, averaged over multiple summers it accounted between 10 and 25 %. Calving was enhanced primarily by buoyancy and water depths, and fluxes were greatest between 2005 and 2010 as the glacier retreated over the deepest part of Bridge Lake. The recent rapid rate of calving is part of a transient stage in the glacier's retreat and is expected to diminish within 10 years as the terminus recedes into shallower water at the proximal end of the lake. These findings are in line with observations from other lake-calving glacier studies across the globe and suggest a common large-scale pattern in calving-induced retreat in lake-terminating alpine glaciers. Despite enhancing glacial retreat, calving remains a relatively small component of ablation and is expected to decrease in importance in the future. Hence, surface melt remains the primary driver of ablation at Bridge Glacier and thus projections of future retreat should be more closely tied to climate.

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Subaqueous calving margin morphology at Mueller, Hooker and Tasman glaciers in Aoraki/Mount Cook National Park, New Zealand

Cited by 32 publications

References 36 publications

On the role of buoyant flexure in glacier calving

On the role of buoyant flexure in glacier calving

Changes in Imja Tsho in the Mount Everest region of Nepal

Ablation from calving and surface melt at lake-terminating Bridge Glacier, British Columbia, 1984–2013

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