Dating the Dye 3 Deep Ice Core by Flow Model Calculations

  1. C.C. Langway Jr.,
  2. H. Oeschger and
  3. W. Dansgaard
  1. N. Reeh,
  2. S. J. Johnsen and
  3. D. Dahl-Jensen

Published Online: 18 MAR 2013

DOI: 10.1029/GM033p0057

Greenland Ice Core: Geophysics, Geochemistry, and the Environment

Greenland Ice Core: Geophysics, Geochemistry, and the Environment

How to Cite

Reeh, N., Johnsen, S. J. and Dahl-Jensen, D. (1985) Dating the Dye 3 Deep Ice Core by Flow Model Calculations, in Greenland Ice Core: Geophysics, Geochemistry, and the Environment (eds C.C. Langway, H. Oeschger and W. Dansgaard), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM033p0057

Author Information

  1. Geophysical Isotope Laboratory, University of Copenhagen, Copenhagen N, Denmark

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1985

ISBN Information

Print ISBN: 9780875900575

Online ISBN: 9781118664155

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Keywords:

  • Ice sheets—Greenland—Addresses, essays, lectures;
  • Greenland Ice Sheet Program

Summary

The primary objective of the ice-flow model calculations presented is to establish a steady state reference, to which measured data from the Dye 3 deep ice core can be compared in order to evaluate whether “irregularities” of the data are due to temporal variations. The influence of the rough topography of the ice sheet base upstream of the drill site and of the irregular distribution of the accumulation rate at the ice sheet surface are included in the flow model, which is based on perturbation techniques. Ice flow is divided into (1) a “basic” flow, accounting for the influence of the trends of the ice thickness and accumulation rate upstream from the drill site, and (2) a “perturbation” flow, accounting for the influence of the upstream perturbations of these quantities. Input data are: (a) the distributions along the flow line of surface and base elevations; (b) the distributions along the flow line of the accumulation rate; and (c) the temperature-depth profile. The dependence of the ice-flow properties on the stress and temperature fields (Glen's law) is taken into account. Flow-law parameters are derived from the modelling of the “basic” flow (giving values in reasonable agreement with hitherto derived values) and are used as input to the “perturbation” flow model. The model is used to calculate theoretical age and annual layer thickness profiles, which are compared with observed profiles along the Dye 3 deep core. The model seems to explain some, though not all “irregularities” of these profiles. Discrepancies are discussed in terms of imperfections of the model, e.g. that a simplified flowline course has been applied, that the model is a first order perturbation model and, that the ice flow may not be two dimensional and certainly not stationary.