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Methane Isotopes from the WAIS Divide Ice Core

Summary

This data set includes methane (CH4) isotope data from the West Antarctic Ice Sheet (WAIS) Divide ice core, WDC05A, in Antarctica. The data include depth, gas age, and the isotopic composition of methane (∂13C and ∂D of CH4). The ice core was collected during the 2005-2006 Antarctic field season. The CH4 isotope data was generated in 2008 using wet extraction methodology. Samples span the last 1,000 years, at a resolution of about 15 years. Data for samples above 69 meters were from firn air, and data below 69 meters from ice. The dating of the ice was based on continuous chemical analyses above 69 meters and Electrical Conductivity/Dielectric Property (ECM/DEP) measurements from ice. Dating uncertainty is estimated to be better than five years.

Data are available via FTP in Microsoft Excel (.xls) tab delimited format.

Citing These Data

The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.

The following example shows how to cite the use of this data set in a publication. List the principal investigators, year of data set release, publisher: NSIDC, and digital media.

Sowers, T. 2009. Methane isotopes from the WAIS divide ice core. Boulder, Colorado, USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5J67DW0.

Overview Table

Category Description
Data format Microsoft Excel (.xls) tab delimited
Spatial coverage and resolution Southernmost Latitude: 79.47°S
Northernmost Latitude: 79.47°S
Westernmost Longitude: 112.09°E
Easternmost Longitude: 112.09°E
Temporal coverage and resolution The WAIS Divide ice core WDC05A was drilled in 2005.
Data were collected in 2008.
Ice age dates start at 1,000 years before present.
File naming convention WAIS_d13C_dD _CH4.xls
File size 32 KB
Parameter(s) Depth
Gas age
Concentration of δ13C and δD in CH4, in parts per million
Procedures for obtaining data Data are available via FTP.

Table of Contents

  1. Contacts and Acknowledgments
  2. Detailed Data Description
  3. Data Access and Tools
  4. Data Acquisition and Processing
  5. References and Related Publications
  6. Document Information

1. Contacts and Acknowledgments

Investigator(s)

Dr. Todd A. Sowers
Penn State University
Earth and Environment Science Institute
Penn State University
University Park, PA 16802
USA

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

Acknowledgements

This research was supported by NSF Office of Polar Programs grant 0440759.

2. Detailed Data Description

Format

Data are in Microsoft Excel (.xls) tab delimited format.

File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/sowers_nsidc_0435/ directory. Within this directory, there is one data file, titled WAIS_d13C_dD _CH4.xls, and a readme file in plain text (.txt) format.


File Naming Convention

This data set consists of one file, WAIS_d13C_dD _CH4.xls, which contains isotope measurements from CH4 samples in the WAIS Divide ice core.

File Size

The data file is 32 KB.

Spatial Coverage

Data are from the WAIS Divide ice core WDC05A in Antarctica.

Southernmost Latitude: 79.47°S
Northernmost Latitude: 79.47°S
Westernmost Longitude: 112.09°E
Easternmost Longitude: 112.09°E

Temporal Coverage

Ice age data ranges from 1,000 years before present to present.

Temporal Resolution

Ice age data have an average resolution of 15 years.

Parameter or Variable

This data set contains depth, age, and concentration measurements for two CH4 isotopes, δ13C and δD. Data for samples above 69 meters is firn air (chemical data), and data below 69 meters is ice, measured in ECM/DEP.

Parameter Description

Table 1. Parameter Description
Parameter Description
Depth Sample depth, in meters below surface (mbs)
Gas age Gas age, in date AD.
d13C (CH4) Concentration of δ13C in CH4, in parts per million Pee Dee Belemnite (PDB)
dD (CH4) Concentration of δD in CH4, in parts per million Standard Mean Ocean Water (SMOW)

Sample Data Record

Depth (mbs) Gas Age (AD) dD(CH4)
(permil SMOW)
Depth (mbs) Gas Age (AD) d13CH4
(permil PDB)
0 2006 -80.0 0 2006 -47.0

Quality Assessment

Data precision is 0.1 meters for depth, 5 years for gas age, 4 parts per million for δD, and 0.3 parts per million for δ13C.

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The data set is 32 KB.

Software and Tools

Data are accessible using spreadsheet software.

Related Data Collections

4. Data Acquisition and Processing

Theory of Measurements

Wet gas extraction, sample dating, and isotope concentration measurement methodologies are detailed in Sowers et. al., 2005, Sowers, 2006, and Sowers, 2009. For samples above 69 meters, measurements were performed on firn air samples and dated using continuous chemical analyses. For samples deeper than 69 meters, analyses were performed on occluded gas bubbles with dating obtained from ECM/DEP counts.

5. References and Related Publications

Mischler, J. A., T. A. Sowers, R. B. Alley, M. Battle, J. R. McConnell, L. Mitchell, T. Popp, E. Sofen, and M. K. Spencer. 2009. Carbon and hydrogen isotopic composition of methane over the last 1000 years. Global Biogeochemical Cycles, 23, GB4024, doi:10.1029/2009GB003460.

Sowers, T. 2006. Late Quaternary atmospheric CH4 isotope record suggests marine clathrates are stable. Science 311: 838-841,doi:10.1126/science.1121235.

Sowers, T., S. Bernard, O. Aballain, J. Chappellaz, J.-M. Barnola and T. Marik. 2005. Records of the d13C of atmospheric CH4 over the last two centuries as recorded in Antarctic snow and ice. Global Biogeochemical Cycles. doi:10.1029/2004GB002408.

Sowers, T. A. 2009. Atmospheric methane isotope records covering the Holocene period. Quaternary Science Reviews. doi:10.1016/j.quascirev.2009.05.023.

The following related documents are available

Table 2. Related Documents
Document Description URL
Antarctic Glaciological Data Center (AGDC) Data Center Web site http://nsidc.org/agdc/
Earth and Environmental Systems: Todd Sowers Investigator Web site http://www.eesi.psu.edu/people/Sowers.shtml
West Antarctic Ice Sheet Divide Ice Core Project Web site http://www.waisdivide.unh.edu/

6. Document Information

Acronyms

The following acronyms are used in this document.

Table 3. Acronyms and Abbreviations
Acronym Description
CH4 Methane
ECM/DEP Electrical Conductivity and Dielectric Property
FTP File Transfer Protocol
MBS Meters Below Surface
NSIDC National Snow and Ice Data Center
PDB Pee Dee Belemnite
SMOW Snow Mean Ocean Water
URL Uniform Resource Locator
YBP Years Before Present

Document Creation Date

20 November 2009

Document URL

http://nsidc.org/data/docs/agdc/nsidc0435_sowers/index.html