A new bathymetry of the Northeast Greenland continental shelf: Constraints on glacial and other processes

Arndt, Jan Erik; Jokat, Wilfried; Dorschel, Boris; Myklebust, R.; Dowdeswell, Julian A.; Evans, Jeffrey

doi:10.1002/2015gc005931

Cited by 60 publications

(107 citation statements)

References 76 publications

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“…The continental shelf of Northeast Greenland is a good example, in which swath-bathymetric evidence of a combination of subglacially produced MSGLs and transverse-to-flow icemarginal retreat moraines demonstrated for the first time that ice of probable LGM age had covered much of the 250 km-wide shelf (e.g. Evans et al 2009;Winkelmann et al 2010;Arndt et al 2015). This compelling submarine geomorphic evidence helped replace an earlier view, based on limited terrestrial Quaternary evidence from the Northeast Greenland coast, that LGM ice had not been much more extensive there than during interglacials (e.g.…”

Section: Volume and Time Frame For Formation Of Submarine Glacial Lanmentioning

confidence: 99%

The variety and distribution of submarine glacial landforms and implications for ice-sheet reconstruction

Dowdeswell

Canals

Jakobsson

et al. 2016

Memoirs

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Glacimarine processes affect about 20% of the global ocean today, and this area expanded considerably under cyclical full-glacial conditions during the Quaternary (Fig. 1) . Many of the submarine landforms produced at the base and margin of past ice sheets remain well preserved on the seafloor in fjords and on high-latitude continental shelves after the retreat of the ice that produced them. These glacial landforms, protected from subaerial erosion and beneath wave-base and tidal currents in water that is often hundreds of metres deep, are gradually buried by both hemipelagic and glacimarine sedimentation; they may be preserved over long periods in the geological record if palaeocontinental shelves are not reworked by subsequent glacier advances or bottom currents ). This means that, first, submarine glacial landforms can be observed at or close to the modern seafloor after retreat of the last great ice sheets from their most recent Quaternary maximum about 18-20 000 years ago using swath-bathymetric mapping systems and, secondly, buried glacial landforms may also be identified and examined within glacial-sedimentary sequences from Quaternary and earlier ice ages using seismic-reflection methods.The development of multibeam echo sounding over the past two decades, coupled with high-accuracy GPS positioning, has allowed morphological mapping of the seafloor at an unprecedented level of detail. In this paper, the variety of submarine glacial landforms observed in modern, Quaternary and more ancient sediments is described. Landforms produced subglacially, those formed at and beyond marine ice-sheet margins, together with the slope processes and bottom currents likely to result in their reworking, are considered along with the sediment volumes of these landforms and the time they take to develop. This is followed by discussion of the significance of submarine glacial landforms and landform-assemblages for reconstruction of the form and flow of past ice sheets, including the former extent and flow direction of ice sheets, whether they are flowing fast as ice streams or slowly in inter-ice stream areas, the nature and rate of ice-sheet deglaciation, conditions at past ice-sheet beds, and inferences on the characteristics of the basal hydrological system and past climatic conditions.

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Section: Volume and Time Frame For Formation Of Submarine Glacial Lanmentioning

confidence: 99%

The variety and distribution of submarine glacial landforms and implications for ice-sheet reconstruction

Dowdeswell

Canals

Jakobsson

et al. 2016

Memoirs

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“…By informing the mouth elevation on IBCAO observational data at a distance of ∼ 20 km from the mouth, the impact of using distant bathymetric observation is exemplified. Equally, as many fjords have at least some information following various recent campaigns (including Schjøth et al, 2012;Dowdeswell et al, 2014;Arndt et al, 2015;Rignot et al, 2016), the use of observational data to constrain the algorithm is illustrated by SynthOBS. The application of these two synthetic approaches has provided bathymetry more representative of the observed elevation profiles (OBS1516) of fjords within the area of interest (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Finally, observations for the fjord mouth could be taken from datasets including IBCAO or others (e.g. Schjøth et al, 2012;Dowdeswell et al, 2014;Arndt et al, 2015;Rignot et al, 2016); however these values may be at a significant distance from the fjord mouth itself, which using the presented approach may result in further under-or overestimation of a given fjord centreline elevation profile.…”

Section: Discussionmentioning

confidence: 99%

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Generating synthetic fjord bathymetry for coastal Greenland

et al. 2017

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Abstract. Bed topography is a critical boundary for the numerical modelling of ice sheets and ice-ocean interactions. A persistent issue with existing topography products for the bed of the Greenland Ice Sheet and surrounding sea floor is the poor representation of coastal bathymetry, especially in regions of floating ice and near the grounding line. Sparse data coverage, and the resultant coarse resolution at the iceocean boundary, poses issues in our ability to model ice flow advance and retreat from the present position. In addition, as fjord bathymetry is known to exert strong control on ocean circulation and ice-ocean forcing, the lack of bed data leads to an inability to model these processes adequately. Since the release of the last complete Greenland bed topography-bathymetry product, new observational bathymetry data have become available. These data can be used to constrain bathymetry, but many fjords remain completely unsampled and therefore poorly resolved. Here, as part of the development of the next generation of Greenland bed topography products, we present a new method for constraining the bathymetry of fjord systems in regions where data coverage is sparse. For these cases, we generate synthetic fjord geometries using a method conditioned by surveys of terrestrial glacial valleys as well as existing sinuous feature interpolation schemes. Our approach enables the capture of the general bathymetry profile of a fjord in north-west Greenland close to Cape York, when compared to observational data. We validate our synthetic approach by demonstrating reduced overestimation of depths compared to past attempts to constrain fjord bathymetry. We also present an analysis of the spectral characteristics of fjord centrelines using recently acquired bathymetric observations, demonstrating how a stochastic model of fjord bathymetry could be parameterised and used to create different realisations.

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“…The publication of different datasets is continuously improving the bathymetry around Greenland (e.g., Arndt et al, 2015;Fenty et al, 2016;Rignot et al, 2015Rignot et al, , 2016Schumann et al, 2012;Williams et al, 2017), even if it is only based on a suite of single-point observations (Andresen et al, 2014) or inversion of gravity data to obtain bathymetry (Porter et al, 2014). Whereas the topography of the onshore area is more easily determined from air and satellite imagery and altimetry (e.g., Korsgaard et al, 2016;Willis et al, 2015), the relief of the submarine parts is hidden by the water column and can only be determined with hydroacoustic methods or aerial gravimetry.…”

mentioning

confidence: 99%

Multibeam bathymetry and CTD measurements in two fjord systems in southeastern Greenland

Kjeldsen

Weinrebe

Bendtsen

et al. 2017

Earth Syst. Sci. Data

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Abstract. We present bathymetry and hydrological observations collected in the summer of 2014 from two fjord systems in southeastern Greenland with a multibeam sonar system. Our results provide a detailed bathymetric map of the fjord complex around the island of Skjoldungen in Skjoldungen Fjord and the outer part of Timmiarmiut Fjord and show far greater depths compared to the International Bathymetric Chart of the Arctic Ocean. The hydrography collected shows different properties in the fjords with the bottom water masses below 240 m in Timmiarmiut Fjord being 1-2 • C warmer than in the two fjords around Skjoldungen, but data also illustrate the influence of sills on the exchange of deeper water masses within fjords. Moreover, evidence of subglacial discharge in Timmiarmiut Fjord, which is consistent with satellite observations of ice mélange set into motion, adds to our increasing understanding of the distribution of subglacial meltwater. Data are available through the PANGAEA website at https://doi.pangaea.de/10.1594/PANGAEA.860627.

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A new bathymetry of the Northeast Greenland continental shelf: Constraints on glacial and other processes

Cited by 60 publications

References 76 publications

The variety and distribution of submarine glacial landforms and implications for ice-sheet reconstruction

The variety and distribution of submarine glacial landforms and implications for ice-sheet reconstruction

Generating synthetic fjord bathymetry for coastal Greenland

Multibeam bathymetry and CTD measurements in two fjord systems in southeastern Greenland

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