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  • INT GLACIOL SOC  (3)
  • Deutsches Nationalkomitee SCAR/IASC  (1)
  • 1
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    INT GLACIOL SOC
    In:  EPIC3Annals of Glaciology, INT GLACIOL SOC, 57(73), pp. 10-18, ISSN: 0260-3055
    Publikationsdatum: 2017-01-02
    Beschreibung: Calving mechanisms are still poorly understood and stress states in the vicinity of ice-shelf fronts are insufficiently known for the development of physically motivated calving laws that match observations. A calving model requires the knowledge of maximum tensile stresses. These stresses depend on different simulation approaches and material models. Therefore, this study compares results of a two-dimensional (2-D) continuum approach using finite elements with results of a one- dimensional (1-D) beam model elaborated in Reeh (1968). A purely viscous model, as well as a viscoelas- tic Maxwell model, is applied for the 2-D case. The maximum tensile stress usually appears at the top surface of an ice shelf. Its location and magnitude are predominantly influenced by the thickness of the ice shelf and the height of the freeboard, the traction-free part at the ice front. More precisely, doub- ling the thickness leads to twice the stress maximum, while doubling the freeboard, based on changes of the ice density, results in an increase of the stress maximum by 61%. Poisson’s ratio controls the evolu- tion of the maximum stress with time. The viscosity and Young’s modulus define the characteristic time of the Maxwell model and thus the time to reach the maximum principal stress.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2017-10-17
    Beschreibung: To understand the dynamics of ice shelves, a knowledge of their internal and basal structure is very important. As the capacity to perform local surveys is limited, remote sensing provides an opportunity to obtain the relevant information. We must prove, however, that the relevant information can be obtained from remote sensing of the surface. That is the aim of this study. The Jelbart Ice Shelf, Antarctica, exhibits a variety of surface structures appearing as stripe-like features in radar imagery. We performed an airborne geophysical survey across these features and compared the results to TerraSAR-X imagery. We find that the stripe-like structures indicate surface troughs coinciding with the location of basal channels and crevasse-like features, revealed by radio-echo sounding. HH and VV polarizations do not show different magnitude. In surface troughs, the local accumulation rate is larger than at the flat surface. Viscoelastic modelling is used to gain an understanding of the surface undulations and their origin. The surface displacement, computed with a Maxwell model, matches the observed surface reasonably well. Our simulations show that the surface troughs develop over decadal to centennial timescales.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
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    INT GLACIOL SOC
    In:  EPIC3Journal of Glaciology, INT GLACIOL SOC, 60(220), pp. 215-232, ISSN: 0022-1430
    Publikationsdatum: 2014-06-23
    Beschreibung: We study the presence and effect of subglacial water on the motion of the inland ice in western Dronning Maud Land. A full-Stokes model including three routing schemes for a thin film of subglacial water and a modification of a Weertman-type sliding relation to account for higher sliding velocities under wet basal conditions were used to perform 200 ka spin-up simulations on a 2.5 km grid. Subsequent 30 ka simulations with wet and dry basal conditions were analysed for the effects of sliding on the thermal regime and velocities. The occurrence of the major ice streams in this area is mainly controlled by the ice and bedrock geometry. Smaller glaciers only appear as pronounced individual glaciers, when subglacial water is taken into account. The thermal regime is affected by creep instabilities produced by an ice rheology including a microscopic water content, leading to a cyclic behaviour on millennial time scales of the ice flow and occurrence of temperate ice at the base.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
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    Deutsches Nationalkomitee SCAR/IASC
    In:  EPIC3Polarforschungsagenda 2030 - Status und Perspektiven der deutschen Polarforschung, Polarforschungsagenda 2030 - Status und Perspektiven der deutschen Polarforschung, Trier, Deutsches Nationalkomitee SCAR/IASC, 156 p., pp. 53-63, ISBN: 978-3-00-057242-5
    Publikationsdatum: 2023-06-21
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Inbook , peerRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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