High basal melting forming a channel at the grounding line of Ross Ice Shelf, Antarctica

Marsh, Oliver J.; Fricker, H. A.; Siegfried, Matthew R.; Christianson, Knut; Nicholls, Keith W.; Corr, Hugh; Catania, G. A.

doi:10.1002/2015gl066612

Cited by 102 publications

(128 citation statements)

References 33 publications

(50 reference statements)

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“…A similar mechanism is proposed by Marsh et al (2016) for the WIS subglacial channel outflow area. If this mechanism is operating at the KIS, it is probable that the strong basal melting by the outflow of its subglacial water system could create a similar channel there.…”

Section: Discussionmentioning

confidence: 89%

“…Comparison of our results to those of Siegfried et al (2016) only confirm that the subglacial water system in the WIS is more active than the KIS trunk subglacial lake system, since volume changes in the WIS system are 3-10 times as large as in the KIS trunk system. Marsh et al (2016) reported extremely large melt rates (22.2±0.2 m yr −1 ) at the site of inferred subglacial water discharge at the Whillans/Mercer Ice Stream grounding line. Strong basal melting is also inferred from the elevation loss rate (up to ∼ 1.5 m yr −1 ) in the narrow channel near the grounding line of the KIS, but the basal melt rate cannot be exactly projected from the observed elevation lowering due to the possibility of bridging stresses across the narrow channel feature.…”

Section: Discussionmentioning

confidence: 99%

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Active subglacial lakes and channelized water flow beneath the Kamb Ice Stream

et al. 2016

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Abstract. We identify two previously unknown subglacial lakes beneath the stagnated trunk of the Kamb Ice Stream (KIS). Rapid fill-drain hydrologic events over several months are inferred from surface height changes measured by CryoSat-2 altimetry and indicate that the lakes are probably connected by a subglacial drainage network, whose structure is inferred from the regional hydraulic potential and probably links the lakes. The sequential fill-drain behavior of the subglacial lakes and concurrent rapid thinning in a channel-like topographic feature near the grounding line implies that the subglacial water repeatedly flows from the region above the trunk to the KIS grounding line and out beneath the Ross Ice Shelf. Ice shelf elevation near the hypothesized outlet is observed to decrease slowly during the study period. Our finding supports a previously published conceptual model of the KIS shutdown stemming from a transition from distributed flow to well-drained channelized flow of subglacial water. However, a water-piracy hypothesis in which the KIS subglacial water system is being starved by drainage in adjacent ice streams is also supported by the fact that the degree of KIS trunk subglacial lake activity is relatively weaker than those of the upstream lakes.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Active subglacial lakes and channelized water flow beneath the Kamb Ice Stream

et al. 2016

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“…the difference between refreezing and melting. Point measurements with phase-sensitive radars (Marsh et al, 2016;Nicholls et al, 2015), global navigation satellite system (GNSS) receivers (Shean et al, 2017), observations from underwater vehicles (Dutrieux et al, 2014) and analysis from high-resolution satellites (Dutrieux et al, 2013;Wilson et al, 2017) have shown that BMB varies spatially on sub-kilometre scales. Ice shelf channels are one expression of localized basal melting (Stanton et al, 2013;Marsh et al, 2016) which, after hydrostatic adjustment, form curvilinear depressions visible at the ice shelf surface (Fig.…”

Section: S Berger Et Al: Spatial Variability Of Ice Shelf Basal Masmentioning

confidence: 99%

“…Processing and acquisition schemes are as outlined previously (Nicholls et al, 2015;Marsh et al, 2016). The radar antennas were positioned at 22 sites.…”

Section: On-site Geophysical Measurementsmentioning

confidence: 99%

Detecting high spatial variability of ice shelf basal mass balance, Roi Baudouin Ice Shelf, Antarctica

et al. 2017

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Abstract. Ice shelves control the dynamic mass loss of ice sheets through buttressing and their integrity depends on the spatial variability of their basal mass balance (BMB), i.e. the difference between refreezing and melting. Here, we present an improved technique -based on satellite observations -to capture the small-scale variability in the BMB of ice shelves. As a case study, we apply the methodology to the Roi Baudouin Ice Shelf, Dronning Maud Land, East Antarctica, and derive its yearly averaged BMB at 10 m horizontal gridding. We use mass conservation in a Lagrangian framework based on high-resolution surface velocities, atmosphericmodel surface mass balance and hydrostatic ice-thickness fields (derived from TanDEM-X surface elevation). Spatial derivatives are implemented using the total-variation differentiation, which preserves abrupt changes in flow velocities and their spatial gradients. Such changes may reflect a dynamic response to localized basal melting and should be included in the mass budget. Our BMB field exhibits much spatial detail and ranges from −14.7 to 8.6 m a −1 ice equivalent. Highest melt rates are found close to the grounding line where the pressure melting point is high, and the ice shelf slope is steep. The BMB field agrees well with on-site measurements from phase-sensitive radar, although independent radar profiling indicates unresolved spatial variations in firn density. We show that an elliptical surface depression (10 m deep and with an extent of 0.7 km × 1.3 km) lowers by 0.5 to 1.4 m a −1 , which we tentatively attribute to a transient adaptation to hydrostatic equilibrium. We find evidence for elevated melting beneath ice shelf channels (with melting being concentrated on the channel's flanks). However, farther downstream from the grounding line, the majority of ice shelf channels advect passively (i.e. no melting nor refreezing) toward the ice shelf front. Although the absolute, satellite-based BMB values remain uncertain, we have high confidence in the spatial variability on sub-kilometre scales. This study highlights expected challenges for a full coupling between ice and ocean models.

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“…Therefore, monitoring the stability of the ice shelves is an integral part of the study of AIS mass changes and the associated sea level rise. As some smaller sized ice shelves in the lower latitude and warmer Antarctic Peninsula region, such as the Larsen B ice shelf, experienced collapses (Scambos 5 et al, 2004;Braun et al, 2009), changes of the two largest ice shelves, Ross Ice Shelf (RIS) and RonneFilchner Ice Shelf (RFIS), have also been intensely studied (Hulbe et al, 1998;Larour et al, 2004;Joughin and MacAyeal, 2005;Makinson et al, 2011;Scheuchl et al, 2012;Marsh et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

A Systematic Study of the Fracturing of Ronne - Filchner Ice Shelf, Antarctica, Using Multisource Satellite Data from 2001 to 2016

Xiao

Liu

et al. 2017

Preprint

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Abstract. We propose a new framework of systematic fracture mapping and major calving event prediction for the large ice shelves in Antarctica using multisource satellite data, including optical imagery, SAR imagery, altimetric data, and stereo mapping imagery. The new framework is implemented and 10 applied for a comprehensive study of the fracturing of Ronne-Filchner Ice Shelf (RFIS), the second largest ice shelf in Antarctica, using a long time dataset dating back to 1957. New remote sensing data that have been made available in the past decade, including Landsat 8, WV-2, ZY-3 and others, greatly enhance our abilities to detect new fractures and monitor large rifts in three dimensions. Two large rifts, Rifts 1 and 2, were newly detected and are comparable to the Grand Chasm that caused a major calving event in 15 the region in 1986. Three-dimensional rift models generated from quasi real-time stereo ZY-3 images revealed important topographic information about the large rifts that can be used to improve the reliability of ice shelf modeling and support enhanced analyses of ice shelf stability. Based on the results of the 2D and 3D fracture mapping, the spatial and temporal analyses of the overall fracture changes and large rift evolutions, i.e., the level of fracturing in RFIS, were slightly increased, particularly at the front of the ice 20 sheet. The overall fracture observations do not seem to suggest immediate significant impacts on the stability of the shelf. However, the most active regional fracturing activities occurred at the front of Filchner Ice Shelf (FIS). A potential upcoming major calving event of FIS is estimated to occur in 2051.The stability of the ice shelf, particularly with regard to the developments of Rifts 1 and 2, should be closely monitored.

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High basal melting forming a channel at the grounding line of Ross Ice Shelf, Antarctica

Cited by 102 publications

References 33 publications

Active subglacial lakes and channelized water flow beneath the Kamb Ice Stream

Active subglacial lakes and channelized water flow beneath the Kamb Ice Stream

Detecting high spatial variability of ice shelf basal mass balance, Roi Baudouin Ice Shelf, Antarctica

A Systematic Study of the Fracturing of Ronne - Filchner Ice Shelf, Antarctica, Using Multisource Satellite Data from 2001 to 2016

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