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  • 1
    Online Resource
    Online Resource
    Large-scale ice-sheet modelling as a means of dating deep ice cores in Greenland
    Cambridge University Press (CUP) ; 1997
    In:  Journal of Glaciology Vol. 43, No. 144 ( 1997), p. 307-310
    Details
    In: Journal of Glaciology, Cambridge University Press (CUP), Vol. 43, No. 144 ( 1997), p. 307-310
    Abstract: The three-dimensional ice-sheet model SICOPOLIS is used to simulate the dynamic/thermody namic behaviour of the entire Greenland ice sheet from 250 000 a BP until today. External forcing consists of a surface-temperature history constructed from δ 18 O data of the GRIP core, a snowfall history coupled linearly to that of the surface temperature, a piecewise linear sea-level scenario and a constant geothermal heat flux. The simulated Greenland ice sheet is investigated in the vicinity of Summit, the position where the maximum elevation is taken, and where the two drill sites GRIP and GISP2 are situated 28km apart from each other. In this region, the agreement between modelled and observed topography and ice temperature turns out to be very good. Computed age-depth profiles for GRIP and GISP2 are presented, which can he used to complete the dating of these cores in the deeper regions where annual-layer counting is not possible. However, artificial diffusion influences the computed ages in a near-basal boundary layer of approximately 15% of the ice thickness, so that the age at the bottom of the cores cannot be predicted yet.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    URL: Article
    DOI: 10.1017/S0022143000003257
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1997
    detail.hit.zdb_id: 2140541-4
    SSG: 14
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  • 2
    Online Resource
    Online Resource
    Modelled ice-sheet margins of three Greenland ice-sheet models compared with a geological record from ice-marginal deposits in central West Greenland
    International Glaciological Society ; 1996
    In:  Annals of Glaciology Vol. 23 ( 1996), p. 52-58
    Details
    In: Annals of Glaciology, International Glaciological Society, Vol. 23 ( 1996), p. 52-58
    Abstract: Ice-sheet modelling is an essential tool for estimating the effect of climate change on the Greenland ice sheet. The large spatial and long-term temporal scales of the ice-sheet model limits the amount of data which can be used to test model results. The geological record is useful because it provides test material on the time-scales typical for the memory of ice sheets (millennia). This paper compares modelled ice-margin positions with a geological scenario of ice-margin positions since the Last Glacial Maximum to the present in West Greenland. Morphological evidence of ice-margin positions is provided by moraines. Moraine systems are dated by 14 C-dated marine shells and terrestrial peat. Three Greenland ice-sheet models are compared. There are distinct differences in modelled ice-margin positions between the models and between model results and the geological record. Disagreement between models and the geological record in the near-coastal area is explained by the inadequate treatment of marginal processes in a tide-water environment. A smaller than present ice sheet around the warm period in the Holocene (Holocene climatic optimum) only occurs if such a period appears in the forcing (ice-core record) or used temporal resolution. Smoothing of the GRIP record with a 2000 year average eliminates the climatic signal related to the Holocene climatic optimum. This underlines the importance of short-term and medium-term variations (decades, centuries) in climatic variables in determining ice-margin positions in the past but also in the future.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    URL: Article
    DOI: 10.1017/S0260305500013252
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1996
    detail.hit.zdb_id: 2122400-6
    SSG: 14
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  • 3
    Online Resource
    Online Resource
    Application of a Polythermal Three-Dimensional Ice Sheet Model to the Greenland Ice Sheet: Response to Steady-State and Transient Climate Scenarios
    American Meteorological Society ; 1997
    In:  Journal of Climate Vol. 10, No. 5 ( 1997-05), p. 901-918
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 10, No. 5 ( 1997-05), p. 901-918
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/1520-0442(1997)010〈0901:AOAPTD〉2.0.CO;2
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 1997
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 4
    Online Resource
    Online Resource
    Deglaciation of the Northern Hemisphere at the onset of the Eemian and Holocene
    International Glaciological Society ; 1999
    In:  Annals of Glaciology Vol. 28 ( 1999), p. 1-8
    Details
    In: Annals of Glaciology, International Glaciological Society, Vol. 28 ( 1999), p. 1-8
    Abstract: High resolution (TIMS) U-series dating of sea-level events obtained from coral-reef complexes suggests that global deglaciation from the Saale (penultimate) glacial to the Eem Interglacial (marine δ 18 O stages 6/5) may have occurred earlier in relation to Milankovitch insolation forcing than that from the Wisconsinan glacial to the Holocene Interglacial (marine δ 18 O stages 2/1). However, the interpretation of these data has been problematic because of the possibility of isotope exchange. In order to investigate whether these different lead—lag relations between Milankovitch forcing and ice volume are feasible from the point of view of large-scale ice-sheet dynamics and thermodynamics, the three-dimensional polythermal ice-sheet model SICOPOLIS (Simulation Code for Poly- thermal Ice Sheets) is applied to the entire Northern Hemisphere (which gives the major contribution to global ice-volume changes due to the relative stability of the Antarctic ice sheet) and simulations through the last two climatic cycles are conducted. The simulations cover the interval from 250 kyr BP until today and are driven by surface-temperature reconstructions of deep ice cores (GRIP, Vostok) and simple parameterizations for the change of precipitation with time. Discussion of the results is focused on the Saale/Eem and the Wisconsinan/Holocene transitions. The amount and rate of deglaciation are in good agreement with the SPECMAP record for both cases, and the evidence of the data for an early start of the Eem Interglacial is supported.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    URL: Article
    DOI: 10.3189/172756499781821643
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1999
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
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    Online Resource
  • 5
    Online Resource
    Online Resource
    A continuum–mechanical formulation for shallow polythermal ice sheets
    The Royal Society ; 1997
    In:  Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences Vol. 355, No. 1726 ( 1997-05-15), p. 921-974
    Details
    In: Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, The Royal Society, Vol. 355, No. 1726 ( 1997-05-15), p. 921-974
    Type of Medium: Online Resource
    ISSN: 1364-503X , 1471-2962
    URL: Article
    DOI: 10.1098/rsta.1997.0050
    RVK:
    AX 30011
    Language: English
    Publisher: The Royal Society
    Publication Date: 1997
    detail.hit.zdb_id: 208381-4
    detail.hit.zdb_id: 1462626-3
    SSG: 11
    SSG: 5,1
    SSG: 5,21
    Location Call Number Limitation Availability
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    Online Resource
  • 6
    Online Resource
    Online Resource
    Modelled ice-sheet margins of three Greenland ice-sheet models compared with a geological record from ice-marginal deposits in central West Greenland
    International Glaciological Society ; 1996
    In:  Annals of Glaciology Vol. 23 ( 1996), p. 52-58
    Details
    In: Annals of Glaciology, International Glaciological Society, Vol. 23 ( 1996), p. 52-58
    Abstract: Ice-sheet modelling is an essential tool for estimating the effect of climate change on the Greenland ice sheet. The large spatial and long-term temporal scales of the ice-sheet model limits the amount of data which can be used to test model results. The geological record is useful because it provides test material on the time-scales typical for the memory of ice sheets (millennia). This paper compares modelled ice-margin positions with a geological scenario of ice-margin positions since the Last Glacial Maximum to the present in West Greenland. Morphological evidence of ice-margin positions is provided by moraines. Moraine systems are dated by 14 C-dated marine shells and terrestrial peat. Three Greenland ice-sheet models are compared. There are distinct differences in modelled ice-margin positions between the models and between model results and the geological record. Disagreement between models and the geological record in the near-coastal area is explained by the inadequate treatment of marginal processes in a tide-water environment. A smaller than present ice sheet around the warm period in the Holocene (Holocene climatic optimum) only occurs if such a period appears in the forcing (ice-core record) or used temporal resolution. Smoothing of the GRIP record with a 2000 year average eliminates the climatic signal related to the Holocene climatic optimum. This underlines the importance of short-term and medium-term variations (decades, centuries) in climatic variables in determining ice-margin positions in the past but also in the future.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    URL: Article
    DOI: 10.3189/S0260305500013252
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1996
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 7
    Online Resource
    Online Resource
    Large-scale ice-sheet modelling as a means of dating deep ice cores in Greenland
    International Glaciological Society ; 1997
    In:  Journal of Glaciology Vol. 43, No. 144 ( 1997), p. 307-310
    Details
    In: Journal of Glaciology, International Glaciological Society, Vol. 43, No. 144 ( 1997), p. 307-310
    Abstract: The three-dimensional ice-sheet model SICOPOLIS is used to simulate the dynamic/thermody namic behaviour of the entire Greenland ice sheet from 250 000 a BP until today. External forcing consists of a surface-temperature history constructed from δ 18 O data of the GRIP core, a snowfall history coupled linearly to that of the surface temperature, a piecewise linear sea-level scenario and a constant geothermal heat flux. The simulated Greenland ice sheet is investigated in the vicinity of Summit, the position where the maximum elevation is taken, and where the two drill sites GRIP and GISP2 are situated 28km apart from each other. In this region, the agreement between modelled and observed topography and ice temperature turns out to be very good. Computed age-depth profiles for GRIP and GISP2 are presented, which can he used to complete the dating of these cores in the deeper regions where annual-layer counting is not possible. However, artificial diffusion influences the computed ages in a near-basal boundary layer of approximately 15% of the ice thickness, so that the age at the bottom of the cores cannot be predicted yet.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    URL: Article
    DOI: 10.3189/S0022143000003257
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1997
    detail.hit.zdb_id: 2140541-4
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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