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      Grain-size evolution of polar firn: a new empirical grain growth parameterization based on X-ray microcomputer tomography measurements

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      General Information:

      Citation:
      Linow, S. , Hörhold, M. and Freitag, J. (2012): Grain-size evolution of polar firn: a new empirical grain growth parameterization based on X-ray microcomputer tomography measurements , Journal of Glaciology, 58 (212), pp. 1245-1252 . doi: 10.3189/2012JoG11J256
      Cite this page as:
      hdl:10013/epic.40394
      DOI:
      10.3189/2012JoG11J256
      Official URL:
      10.3189/2012JoG11J256
      Contact Email:
      Stefanie.Linow@awi.de
      Related Data:

      Abstract:

      Firn microstructure properties from six different sites in Greenland and Antarctica are investigated by means of X-ray microcomputer tomography. The optical effective radius is calculated from the specific surface area (SSA) and used as a measure of grain size. It is shown that the recently introduced spherical approximation of firn grains using the effective radius R_eff is representative of grain size in the microwave frequency region. The measured profiles show the well-known increase of grain size with depth at all sites, where the increase is largest at near-surface depths. A large variability in grain size on the decimeter-to-centimeter scale as a result of different grain properties of single layers is superimposed on the overall trend at each site. A simple empirical parameterization of grain-size evolution is developed which allows the rapid grain growth in the uppermost layers of the firn to be predicted. The growth is driven by strong seasonal and diurnal temperature gradients. The model can be used to simulate grain-size profiles required by models of firn/microwave interaction (e.g. for retrieval of accumulation rates from satellite microwave sensors) in a more realistic fashion.

      Further Details:

      Item Type:
      Article
      Authors:
      Linow, Stefanie ; Hörhold, Maria ; Freitag, Johannes
      Divisions:
      AWI Organizations > Geosciences > Glaciology
      AWI Organizations > Climate Sciences > Polar Meteorology
      Primary Division:
      Organizations > AWI Organizations > Climate Sciences
      Programs:
      Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 1: The Changing Arctic and Antarctic > WP 1.1: Role of Ice Sheets in the Earth System
      Primary Topic:
      Helmholtz Programs > Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 1: The Changing Arctic and Antarctic
      Eprint ID:
      31503
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      Alfred-Wegener-Institut
      Helmholtz-Zentrum für Polar-
      und Meeresforschung
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