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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 8, issue 6 | Copyright
Clim. Past, 8, 1881-1895, 2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 23 Nov 2012

Research article | 23 Nov 2012

An automated approach for annual layer counting in ice cores

M. Winstrup1,*, A. M. Svensson1, S. O. Rasmussen1, O. Winther2, E. J. Steig3, and A. E. Axelrod4 M. Winstrup et al.
  • 1Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
  • 2DTU Informatics, Technical University of Denmark, Lyngby, Denmark
  • 3Quaternary Research Center & Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
  • 4Department of Electrical Engineering, University of Washington, Seattle, Washington, USA
  • *now at: Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA

Abstract. A novel method for automated annual layer counting in seasonally-resolved paleoclimate records has been developed. It relies on algorithms from the statistical framework of hidden Markov models (HMMs), which originally was developed for use in machine speech recognition. The strength of the layer detection algorithm lies in the way it is able to imitate the manual procedures for annual layer counting, while being based on statistical criteria for annual layer identification. The most likely positions of multiple layer boundaries in a section of ice core data are determined simultaneously, and a probabilistic uncertainty estimate of the resulting layer count is provided, ensuring an objective treatment of ambiguous layers in the data. Furthermore, multiple data series can be incorporated and used simultaneously. In this study, the automated layer counting algorithm has been applied to two ice core records from Greenland: one displaying a distinct annual signal and one which is more challenging. The algorithm shows high skill in reproducing the results from manual layer counts, and the resulting timescale compares well to absolute-dated volcanic marker horizons where these exist.

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