The SP19 chronology for the South Pole Ice Core – Part 2: gas chronology, Δage, and smoothing of atmospheric records

J. A. Epifanio; E. J. Brook; C. Buizert; J. S. Edwards; T. A. Sowers; E. C. Kahle; J. P. Severinghaus; E. J. Steig; D. A. Winski; D. A. Winski; E. C. Osterberg; T. J. Fudge; M. Aydin; E. Hood; M. Kalk; K. J. Kreutz; K. J. Kreutz; D. G. Ferris; J. A. Kennedy

doi:10.5194/cp-16-2431-2020

Climate of the Past (Dec 2020)

The SP19 chronology for the South Pole Ice Core – Part 2: gas chronology, Δage, and smoothing of atmospheric records

J. A. Epifanio,
E. J. Brook,
C. Buizert,
J. S. Edwards,
T. A. Sowers,
E. C. Kahle,
J. P. Severinghaus,
E. J. Steig,
D. A. Winski,
D. A. Winski,
E. C. Osterberg,
T. J. Fudge,
M. Aydin,
E. Hood,
M. Kalk,
K. J. Kreutz,
K. J. Kreutz,
D. G. Ferris,
J. A. Kennedy

Affiliations

J. A. Epifanio: College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
E. J. Brook: College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
C. Buizert: College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
J. S. Edwards: College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
T. A. Sowers: The Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, USA
E. C. Kahle: Department of Earth and Space Science, University of Washington, Seattle, WA, USA
J. P. Severinghaus: Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
E. J. Steig: Department of Earth and Space Science, University of Washington, Seattle, WA, USA
D. A. Winski: School of Earth and Climate Sciences, University of Maine, Orono, ME, USA
D. A. Winski: Climate Change Institute, University of Maine, Orono, ME, USA
E. C. Osterberg: Department of Earth Sciences, Dartmouth College, Hanover, NH, USA
T. J. Fudge: Department of Earth and Space Science, University of Washington, Seattle, WA, USA
M. Aydin: Department of Earth System Science, University of California, Irvine, CA, USA
E. Hood: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA
M. Kalk: College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
K. J. Kreutz: School of Earth and Climate Sciences, University of Maine, Orono, ME, USA
K. J. Kreutz: Climate Change Institute, University of Maine, Orono, ME, USA
D. G. Ferris: Department of Earth Sciences, Dartmouth College, Hanover, NH, USA
J. A. Kennedy: Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD, USA

DOI: https://doi.org/10.5194/cp-16-2431-2020
Journal volume & issue: Vol. 16
pp. 2431 – 2444

Abstract

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A new ice core drilled at the South Pole provides a 54 000-year paleoenvironmental record including the composition of the past atmosphere. This paper describes the SP19 chronology for the South Pole atmospheric gas record and complements a previous paper (Winski et al., 2019) describing the SP19 ice chronology. The gas chronology is based on a discrete methane (CH4) record with 20- to 190-year resolution. To construct the gas timescale, abrupt changes in atmospheric CH4 during the glacial period and centennial CH4 variability during the Holocene were used to synchronize the South Pole gas record with analogous data from the West Antarctic Ice Sheet Divide ice core. Stratigraphic matching based on visual optimization was verified using an automated matching algorithm. The South Pole ice core recovers all expected changes in CH4 based on previous records. Gas transport in the firn results in smoothing of the atmospheric gas record with a smoothing function spectral width that ranges from 30 to 78 years, equal to 3 % of the gas-age–ice-age difference, or Δage. The new gas chronology, in combination with the existing ice age scale from Winski et al. (2019), allows a model-independent reconstruction of the gas-age–ice-age difference through the whole record, which will be useful for testing firn densification models.

Published in Climate of the Past

ISSN: 1814-9324 (Print); 1814-9332 (Online)
Publisher: Copernicus Publications
Country of publisher: Germany
LCC subjects: Technology: Environmental technology. Sanitary engineering: Environmental pollution; Technology: Environmental technology. Sanitary engineering: Environmental protection; Geography. Anthropology. Recreation: Environmental sciences
Website: https://www.climate-of-the-past.net/index.html

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