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Reconstruction of temperature, accumulation rate, and layer thinning from an ice core at South Pole using a statistical inverse method
  • +11
  • Emma C. Kahle,
  • Eric J. Steig,
  • Tyler R. Jones,
  • T.J. Fudge,
  • Michelle Rebecca Koutnik,
  • Valerie Morris,
  • Bruce Vaughn,
  • Andrew Schauer,
  • C. Max Stevens,
  • Howard Conway,
  • Edwin D Waddington,
  • Christo Buizert,
  • Jenna Epifanio,
  • James W.C. White
Emma C. Kahle
University of Washington, University of Washington, University of Washington
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Eric J. Steig
University of Washington, University of Washington, University of Washington

Corresponding Author:[email protected]

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Tyler R. Jones
University of Colorado Boulder, University of Colorado Boulder, University of Colorado Boulder
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T.J. Fudge
University of Washington, University of Washington, University of Washington
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Michelle Rebecca Koutnik
University of Washington, University of Washington, University of Washington
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Valerie Morris
University of Colorado Boulder, University of Colorado Boulder, University of Colorado Boulder
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Bruce Vaughn
University of Colorado Boulder, University of Colorado Boulder, University of Colorado Boulder
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Andrew Schauer
University of Washington, University of Washington, University of Washington
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C. Max Stevens
University of Washignton, University of Washignton, University of Washignton
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Howard Conway
University of Washington, University of Washington, University of Washington
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Edwin D Waddington
University of Washington, University of Washington, University of Washington
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Christo Buizert
Oregon State University, Oregon State University, Oregon State University
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Jenna Epifanio
Oregon State University, Oregon State University, Oregon State University
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James W.C. White
University of Colorado Boulder, University of Colorado Boulder, University of Colorado Boulder
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Abstract

Data from the South Pole ice core (SPC14) are used to constrain climate conditions and ice-flow-induced layer thinning for the last 54,000 years. Empirical constraints are obtained from the SPC14 ice and gas timescales, used to calculate annual-layer thickness and the gas-ice age difference (Δage), and from high-resolution measurements of water isotopes, used to calculate the water-isotope diffusion length. Both Δage and diffusion length depend on firn properties and therefore contain information about past temperature and snow-accumulation rate. A statistical inverse approach is used to obtain an ensemble of reconstructions of temperature, accumulation-rate, and thinning of annual layers in the ice sheet at the SPC14 site. The traditional water-isotope/temperature relationship is not used as a constraint; the results therefore provide an independent calibration of that relationship. The temperature reconstruction yields a glacial-interglacial temperature change of 6.7 ± 1.0 °C at the South Pole. The sensitivity of δ180 to temperature is 0.99 ± 0.03 ‰/°C, significantly greater than the spatial slope of ~0.8 ‰/°C that has been used previously to determine temperature changes from East Antarctic ice core records. The reconstructions of accumulation rate and ice thinning show millennial-scale variations in the thinning function as well as decreased thinning at depth compared to the results of a 1-D ice flow model, suggesting influence of bedrock topography on ice flow.
16 Jul 2021Published in Journal of Geophysical Research: Atmospheres volume 126 issue 13. 10.1029/2020JD033300