Erosion by an Alpine glacier

Herman, Frédéric; Beyssac, Olivier; Brughelli, Mattia; Lane, Stuart N.; Leprince, S.; Adatte, Thierry; Lin, Jiao; Avouac, Jean Philippe; Cox, Simon C.

doi:10.1126/science.aab2386

Cited by 166 publications

(250 citation statements)

References 48 publications

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“…Five times the amount of water flowing along the GIS bed by the end of the century will likely increase sediment removal (Bogen and Bønsnes, 2003). If increased VHD and water at the bed of the GIS simultaneously cause sediment removal rates to increase while reducing glacier velocities (Tedstone et al, 2015) and therefore the production of sediment (Herman et al, 2015), the state of the bed may change over the coming centuries to millennia from potentially deformable subglacial sediments to rigid bedrock (Weertman, 1964;Kamb, 1970;Tulaczyk et al, 2000;Bougamont et al, 2014) …”

Section: Erosion and Sediment Transportmentioning

confidence: 99%

The past, present, and future viscous heat dissipation available for Greenland subglacial conduit formation

Mankoff

Tulaczyk

2017

The Cryosphere

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Abstract. Basal hydrology of the Greenland Ice Sheet (GIS) influences its dynamics and mass balance through basal lubrication and ice-bed decoupling or efficient water removal and ice-bed coupling. Variations in subglacial water pressure through the seasonal evolution of the subglacial hydrological system help control ice velocity. Near the ice sheet margin, large basal conduits are melted by the viscous heat dissipation (VHD) from surface runoff routed to the bed. These conduits may lead to efficient drainage systems that lower subglacial water pressure, increase basal effective stress, and reduce ice velocity. In this study we quantify the energy available for VHD historically at present and under future climate scenarios. At present, 345 km 3 of annual runoff delivers 66 GW to the base of the ice sheet per year. These values are already ∼ 50 % more than the historical 1960-1999 value of 46 GW. By 2100 under IPCC AR5 RCP8.5 (RCP4.5) scenarios, 1278 (524) km 3 of runoff may deliver 310 (110) GW to the ice sheet base. Hence, the ice sheet may experience a 5-to-7-fold increase in VHD in the near future which will enhance opening of subglacial conduits near the margin and will warm basal ice in the interior. The other significant basal heat source is geothermal heat flux (GHF), which has an estimated value of 36 GW within the present-day VHD area. With increasing surface meltwater penetration to the bed the basal heat budget in the active basal hydrology zone of the GIS will be increasingly dominated by VHD and relatively less sensitive to GHF, which may result in spatial changes in the ice flow field and in its seasonal variability.

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Section: Erosion and Sediment Transportmentioning

confidence: 99%

The past, present, and future viscous heat dissipation available for Greenland subglacial conduit formation

Mankoff

Tulaczyk

2017

The Cryosphere

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“…Prior to this study the few repeat geophysical surveys of the ice-bed interface in Alaska and Antarctica yielded subglacial erosion rates of 1000-3900 mm a −1 (Motyka et al, 2006;Smith et al, 2007Smith et al, , 2012, far exceeding the 0.01-100 mm a −1 range traditionally reported as characteristic of glacial settings using proglacial sediment yields (Hallet et al, 1996;Koppes and Hallet, 2006;Koppes and Montgomery, 2009;Cowton et al, 2012;Herman et al, 2015) (Fig. 6).…”

Section: Implications For Subglacial Sediment Transport and Future Sumentioning

confidence: 99%

How dynamic are ice-stream beds?

et al. 2018

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Abstract. Projections of sea-level rise contributions from West Antarctica's dynamically thinning ice streams contain high uncertainty because some of the key processes involved are extremely challenging to observe. An especially poorly observed parameter is sub-decadal stability of ice-stream beds, which may be important for subglacial traction, till continuity and landform development. Only two previous studies have made repeated geophysical measurements of ice-stream beds at the same locations in different years, but both studies were limited in spatial extent. Here, we present the results from repeat radar measurements of the bed of Pine Island Glacier, West Antarctica, conducted 3-6 years apart, along a cumulative ∼ 60 km of profiles. Analysis of the correlation of bed picks between repeat surveys shows that 90 % of the bed displays no significant change despite the glacier increasing in speed by up to 40 % over the last decade. We attribute the negligible detection of morphological change at the bed of Pine Island Glacier to the ubiquitous presence of a deforming till layer, wherein sediment transport is in steady state, such that sediment is transported along the basal interface without inducing morphological change to the radarsounded basal interface. Given the precision of our measurements, the upper limit of subglacial erosion observed here is 500 mm a −1 , far exceeding erosion rates reported for glacial settings from proglacial sediment yields, but substantially below subglacial erosion rates of 1.0 m a −1 previously reported from repeat geophysical surveys in West Antarctica.

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“…The Fast Fourier Transformation (FFT) correlation engine embedded in the algorithm of COSI-Corr [8][9][10][11][12][13][14][15] improves the traditional peak correlation algorithm, and its accuracy can reach 1/50 pixel [8]. Thus, we select COSI-Corr as the data processing platform.…”

Section: Experimental Design and Data Processingmentioning

confidence: 99%

“…The COSI-Corr is originally used to extract crustal deformation induced by earthquake released by Tectonics Observatory at Caltech in 2008 [8,9]. The technique is now widely used to monitor the earth surface changes and dynamics [8][9][10][11][12][13][14][15]. As richer and constantly updated satellite observation data become available, the application of optical images cross-correlation technique has been expanded to fields such as glacier flow velocity extraction [10][11][12], quantification of sand dune migration [13][14][15], terrain-deformation measurements of slow landslides [16], monitoring process of significant rift events [17], volcanic monitoring [18] and particularly extensive coseismic deformation extraction [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Spatio-Temporal Error Sources Analysis and Accuracy Improvement in Landsat 8 Image Ground Displacement Measurements

et al. 2016

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Abstract:Because of the advantages of low cost, large coverage and short revisit cycle, Landsat 8 images have been widely applied to monitor earth surface movements. However, there are few systematic studies considering the error source characteristics or the improvement of the deformation field accuracy obtained by Landsat 8 image. In this study, we utilize the 2013 Mw 7.7 Balochistan, Pakistan earthquake to analyze error spatio-temporal characteristics and elaborate how to mitigate error sources in the deformation field extracted from multi-temporal Landsat 8 images. We found that the stripe artifacts and the topographic shadowing artifacts are two major error components in the deformation field, which currently lack overall understanding and an effective mitigation strategy. For the stripe artifacts, we propose a small spatial baseline (<200 m) method to avoid the stripe artifacts effect on the deformation field. We also propose a small radiometric baseline method to reduce the topographic shadowing artifacts and radiometric decorrelation noises. Those performances and accuracy evaluation show that these two methods are effective in improving the precision of deformation field. This study provides the possibility to detect subtle ground movement with higher precision caused by earthquake, melting glaciers, landslides, etc., with Landsat 8 images. It is also a good reference for error source analysis and corrections in deformation field extracted from other optical satellite images.

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Erosion by an Alpine glacier

Cited by 166 publications

References 48 publications

The past, present, and future viscous heat dissipation available for Greenland subglacial conduit formation

The past, present, and future viscous heat dissipation available for Greenland subglacial conduit formation

How dynamic are ice-stream beds?

Spatio-Temporal Error Sources Analysis and Accuracy Improvement in Landsat 8 Image Ground Displacement Measurements

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