Calving Behavior at Rink Isbræ, West Greenland, from Time-Lapse Photos

Medrzycka, Dorota; Benn, Douglas I.; Box, Jason E.; Copland, Luke; Balog, James

doi:10.1657/aaar0015-059

Cited by 36 publications

(50 citation statements)

References 59 publications

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“…By contrast, critical strain rates can be measured. Although 0.01 yr −1 is often given as reference threshold (Meier, 1958), observed threshold normal strain rates for the initiation of crevasses span over 2 orders of magnitude (Colgan et al, 2016). The estimation of critical strain rates has been rendered easier through the use of automatic camera and aerial photogrammetry combined with feature-tracking techniques (Colgan et al, 2016;Messerli and Grinsted, 2015).…”

Section: G Jouvet Et Al: Initiation Of a Major Calving Eventmentioning

confidence: 99%

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Initiation of a major calving event on the Bowdoin Glacier captured by UAV photogrammetry

Jouvet¹,

Weidmann²,

Seguinot³

et al. 2017

The Cryosphere

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Abstract. In this paper, we analyse the calving activity of the Bowdoin Glacier, north-western Greenland, in 2015 by combining satellite images, UAV (unmanned aerial vehicle) photogrammetry and ice flow modelling. In particular, a highresolution displacement field is inferred from UAV orthoimages taken immediately before and after the initiation of a large fracture, which induced a major calving event. A detailed analysis of the strain rate field allows us to accurately map the path taken by the opening crack. Modelling results reveal (i) that the crack was more than half-thickness deep, filled with water and getting irreversibly deeper when it was captured by the UAV and (ii) that the crack initiated in an area of high horizontal shear caused by a local basal bump immediately behind the current calving front. The asymmetry of the bed at the front explains the systematic calving pattern observed in May and July-August 2015. As a corollary, we infer that the calving front of the Bowdoin Glacier is currently stabilized by this bedrock bump and might enter into an unstable mode and retreat rapidly if the glacier keeps thinning in the coming years. Beyond this outcome, our study demonstrates that the combination of UAV photogrammetry and ice flow modelling is a promising tool to horizontally and vertically track the propagation of fractures responsible for large calving events.

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Section: G Jouvet Et Al: Initiation Of a Major Calving Eventmentioning

confidence: 99%

“…However, observations in Greenland (e.g. Medrzycka et al, 2016) show that large-scale, occasional calving events often contribute more to total calving loss than small-scale frequent events.…”

Section: Introductionmentioning

confidence: 99%

Initiation of a major calving event on the Bowdoin Glacier captured by UAV photogrammetry

Jouvet¹,

Weidmann²,

Seguinot³

et al. 2017

The Cryosphere

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“…Buoyancy-driven calving is an important process on large, fast-flowing outlet glaciers [59][60][61][62][63][64]. Rapid ice flow into deep water can create 'super-buoyant' conditions, in which ice fronts are out of hydrostatic equilibrium and subject to large upward-directed torque forces (Fig.…”

Section: Processes Of Frontal Ablationmentioning

confidence: 99%

“…Geometric considerations show that block rotation is associated with the growth of basal crevasses, which eventually lead to calving and overturning of the terminal block, usually closely followed by block disintegration. Buoyancy-driven calving events can be very large, typically affecting the full thickness of the glacier for many hundreds of metres across-and along-flow [59,60,64]. Collisions between capsizing bergs and the glacier terminus are the likely source of seismic signals associated with large calving events [65][66][67].…”

Section: Processes Of Frontal Ablationmentioning

confidence: 99%

“…Analysis of Extreme Ice Survey time-lapse camera data on Rink Glacier by Medrzycka et al [60] has shown that frequent, small calving events occur in the vicinity of upwelling plumes, whereas infrequent, large, buoyancy-driven events occur where the glacier terminates in deep water. It is likely that the relative contribution of buoyancy-driven and melt-undercutting (and other calving processes such as the release of tabular bergs in response to longitudinal extension) varies greatly between glaciers in Greenland.…”

Section: Processes Of Frontal Ablationmentioning

confidence: 99%

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Glacier Calving in Greenland

Benn

Cowton

Todd

et al. 2017

Curr Clim Change Rep

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In combination, the breakaway of icebergs (calving) and submarine melting at marine-terminating glaciers account for between one third and one half of the mass annually discharged from the Greenland Ice Sheet into the ocean. These ice losses are increasing due to glacier acceleration and retreat, largely in response to increased heat flux from the oceans. Behaviour of Greenland's marine-terminating ('tidewater') glaciers is strongly influenced by fjord bathymetry, particularly the presence of 'pinning points' (narrow or shallow parts of fjords that encourage stability) and overdeepened basins (that encourage rapid retreat). Despite the importance of calving and submarine melting and significant advances in monitoring and understanding key processes, it is not yet possible to predict the tidewater glacier response to climatic and oceanic forcing with any confidence. The simple calving laws required for ice-sheet models do not adequately represent the complexity of calving processes. New detailed process models, however, are increasing our understanding of the key processes and are guiding the design of improved calving laws. There is thus some prospect of reaching the elusive goal of accurately predicting future tidewater glacier behaviour and associated rates of sea-level rise.

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