Cosmogenic Radionuclides in the Siple Dome A Ice Core

Summary

This data set includes a record of cosmogenic radionuclide concentrations in the Siple Dome A ice core collected as part of the West Antarctic ice core program. The investigators measured profiles of both ¹⁰Be (half-life = 1.5x10⁶ years) and ³⁶Cl (half-life = 3.0x10⁵ years) in the entire ice core which spans the time period from the present to about 100,000 years before present. These data are being used for perfecting the ice core chronology, deducing the history of solar activity, deducing the history of variations in the geomagnetic field, and studying the possible role of solar variations on climate.

Data are distributed as a PDF file and are available via FTP.

Citing These Data

Nishiizumi, K., and R. Finkel. 2007. Cosmogenic radionuclides in the Siple Dome A ice core. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5XK8CGS.

Overview Table

Category	Description
Data format	PDF
Spatial coverage	Southernmost Latitude: 81.6588° S Northernmost Latitude: 81.6588° S Westernmost Longitude: 148.8120° W Easternmost Longitude: 148.8120° W
Temporal coverage	Approximately 100 kyr BP to 9 January 1997
File naming convention	SD-10Be_Report.pdf SD-36Cl_Report.pdf
File size	75 KB - 89 KB
Parameter	Cosmogenic radionuclides: 10Be and 36Cl
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. Document Information

1. Contacts and Acknowledgments

Investigators

Kunihiko Nishiizumi
Space Sciences Laboratory
University of California, Berkeley
7 Gauss Way
Berkeley, CA 94720-7450 USA

Robert Finkel
Lawrence Livermore National Laboratory
PO Box 808 (L-232)
Livermore, CA 94550 USA

Technical Contact

Acknowledgements

This research was supported by the National Science Foundation (NSF) Office of Polar Programs (OPP) grant OPP-0126343.

2. Detailed Data Description

File Structure

The file SD-10Be_Report.pdf contains data for ¹⁰Be organized into five columns representing the following information.

Top (m)	Sample distance from the top of the core
Bottom(m)	Sample distance from the bottom of the core
Length (m)	Sample length
Solution Mass (g)	Mass of 10Be in the sample
10Be (atom/g)	Concentration of 10Be

The file SD-36Cl_Report.pdf contains data for ³⁶Cl organized into 11 columns representing the following information.

ID	Sample identification
Top (m)	Sample distance from the top of the core
Bottom(m)	Sample distance from the bottom of the core
Length (m)	Sample length
Solution Mass (g)	Mass of 36Cl in the sample
Cl Carrier (mg)	Mass of Cl carrier
Cl in ice (ppb)	Concentration of Cl in ice
36Cl/Cl (atom/atom)	Ratio of 36Cl to Cl
±36Cl/Cl (atom/atom)	Ratio of ±36Cl to Cl
36Cl (atom/g)	Concentration of 36Cl
±36Cl (atom/g)	Concentration of ±36Cl

Spatial Coverage

Southernmost Latitude: 81.6588° S
Northernmost Latitude: 81.6588° S
Westernmost Longitude: 148.8120° W
Easternmost Longitude: 148.8120° W

Spatial Resolution

The top of Siple Dome A ice core was 0.377 m in depth and the bottom was 1003.809 m in depth. The core has a diameter of 13.3 cm. Investigators collected samples at variable intervals and depths.

Temporal Coverage

Data represent a time span of approximately 100,000 years before present. The Siple Dome A ice core was drilled on 9 January 1997.

Parameter

Cosmogenic radionuclides in polar ice cores have been used to study the long-term variations in several important geophysical variables, including solar activity, geomagnetic field strength, atmospheric circulation, snow accumulation rates, and others. The investigators will use cosmogenic radionuclide concentrations to study climate history through the effects of atmospheric circulation and of atmospheric chemistry on nuclide deposition.

Quality Assessment

These are preliminary data of cosmogenic radionuclides (¹⁰Be and ³⁶Cl) in the Siple Dome A ice core. Depths are at variable intervals and are not continuous. Investigators have provided ³⁶Cl/Cl ratios. Calculation of ³⁶Cl concentration (atom/g) requires the Cl concentration in the same sample, which is not available. All ¹⁰Be results have more than 20% uncertainty due to accelerator mass spectrometry (AMS) calibration issues and the uncertainty in the volume of melting water; these require large corrections.

3. Data Access and Tools

Data Access

Data are available via FTP.

Related Data Collections

• Firn Air Isotope and Temperature Measurements from Siple Dome and South Pole
• Siple Dome Highlights: Stable Isotopes

4. Data Acquisition and Processing

Sensor or Instrument Description

Investigators carried out chemical measurements at the Lawrence Livermore National Laboratory (LLNL) accelerator mass spectrometry (AMS) facility.

Data Acquisition Methods

All data were obtained after melting the ice, filtration, anion exchange chromatograph, cation exchange chromatograph, chemical separations, purifications, and AMS.

5. Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AMS	Accelerator mass spectrometry
Be	Beryllium
BP	Before present
Cl	Chlorine
FTP	File Transfer Protocol
LLNL	Lawrence Livermore National Laboratory
kyr	Thousand years
NSF	National Science Foundation
NSIDC	National Snow and Ice Data Center
OPP	Office of Polar Programs
PDF	Portable Document Format
ppb	Parts per billion
URL	Uniform Resource Locator

Document Creation Date

May 2007

Document URL

http://nsidc.org/data/docs/agdc/nsidc0307_nishiizumi/index.html