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Data Set ID:
NSIDC-0499

Microparticle, Conductivity, and Density Measurements from the WAIS Divide Deep Ice Core, Antarctica, Version 1

This data set includes microparticle concentration, electrical conductivity, and density measurements from the West Antarctic Ice Sheet (WAIS) Divide deep ice core, WDC06A. Microparticle concentration data are reported as total particles per ml of meltwater. Concentration was measured using a laser detector and the University of Maine WAIS Melt Monitor system. Conductivity is measured in micro-Siemens per cm (uS/cm). Density data were collected on 3 by 3 by 100 cm sticks from the WDC06A core, using the Maine Automated Density Gauge Experiment (MADGE). Density data span 0 to 160 m in depth, while the particle and conductivity measurements span the upper 577 m of the core.

Data are available via FTP in ASCII text format (.txt).

Geographic Coverage

Spatial Coverage:
  • N: -79.482778, S: -79.482778, E: -112.088333, W: -112.088333

  • N: -79.482778, S: -79.482778, E: 112.088333, W: 112.088333

Spatial Resolution: Not Specified
Temporal Coverage:
  • 1 January 2006 to 31 December 2006
Temporal Resolution: Not specified
Parameter(s):
  • Ice Core Records > Electrical Properties
  • Ice Core Records
  • Glaciers/Ice Sheets > Ice Sheets
  • Ice Core Records > Ions
  • Ice Core Records > Isotopes
  • Ice Core Records > Particulate Matter
  • Snow/Ice > Snow/Ice Chemistry
Platform(s) FIELD INVESTIGATION, LABORATORY
Sensor(s): Not specified
Data Format(s):
  • ASCII Text
Version: V1
Data Contributor(s): Karl Kreutz, Gordon Hamilton, Daniel Breton, Bess Koffman

Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Kreutz, K., B. Koffman, D. Breton, and G. S. Hamilton. 2011. Microparticle, Conductivity, and Density Measurements from the WAIS Divide Deep Ice Core, Antarctica, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5K07264. [Date Accessed].

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Detailed Data Description

Format

Data are available in ASCII text (.txt) format.

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File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0499_kreutz_V01/ directory. Within this directory, there are four data files as described in Table 1.

Table 1. File Description
Filename Description
WDC06A_electrical_conductivity.txt Electrical conductivity measurements, reported as micro-Siemens per cm (μS/cm)
WDC06A_particle_concentration.txt Microparticle concentration, reported as total particles per ml of of meltwater
WDC06A_rho_clean.txt Density measurements, with core breaks removed. Recommended for observing the overall density trend of high quality core.
WDC06A_rho_dirty.txt Density measurements, retaining all the denisty data including those crossing over core breaks. Recommended for accumulation studies.
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File Naming Convention

Files are named according to the following convention and as described in Table 2:

WDC06A_data_type.txt

Where:

Table 2. File Naming Convention
Variable Description
WDC06A Ice core name
data_type Data type
txt ASCII text file extension
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File Size

Files range in size from 1360 KB to 15 MB.

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Volume

Total volume of the data is 23 MB.

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Spatial Coverage

Data are from the WDC06A deep ice core on the West Antarctic Ice Sheet.

Southernmost Latitude: 79°28.058' S
Northernmost Latitude: 79°28.058' S
Westernmost Longitude: 112°05.189' W
Easternmost Longitude: 112°05.189' W

Vertical Coverage and Resolution

Table 3. Vertical Coverage and Resolution
Data Type Vertical Coverage Vertical Resolution
Microparticle Concentration 0 to 577 m 1 cm
Electrical Conductivity 0 to 577 m 1 cm
Density 0 to 160 m 0.33 cm
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Temporal Coverage
Table 4. Temporal Coverage and Resolution
Data Type Temporal Coverage Temporal Resolution
Microparticle Concentration -427 C. E. to present
Electrical Conductivity -427 C. E. to present
Density 1384 to present sub-annual
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Parameter or Variable

Measurements include microparticle concentration, electrical conductivity, and density measurements made on the WAIS Divide deep ice core, WDC06A. Particle and conductivity measurements span the top 577 m of the ice core, while high-resolution density measurements span only the top 160 m.

Parameter Description

Table 5. Parameter Description
Data Type Parameters
Microparticle Concentration Depth (m)
Particle concentration in particles per millileter (p/ml)
Electrical Conductivity Depth (m)
Electrical conductivity in microSiemens per centimeter (μS/cm)
Density Depth (m)
Density in grams per cubic centimeter (g/cm^3)
One-sigma uncertainty in density (g/cm^3)
Gamma-ray beam pathlength in sample (cm) (This can be useful to determine if a particular density data point was recorded over an irregular section of core)
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Software and Tools

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Data Acquisition and Processing

Data were obtatained from the WAIS Divide deep ice core, WDC06A, which was drilled on the West Antarctic Ice Sheet in 2006-2008.

Theory of Measurements

Microparticle Measurements

Particle concentration was measured using a Klotz Abakus laser particle detector and the University of Maine WAIS Melt Monitor system, which allowed the investigators to track flow through the detector (Breton, et. al., in prep).

Conductivity Measurements

Conductivity was analyzed using an Amber Science flow-through meter.

Density Measurements

Density data were collected on 3x3x100 cm sticks from the WDC06A core (from 0 to 160 m depth) using the Maine Automated Density Gauge Experiment (MADGE). The depth, density, one-sigma uncertainty in the reported density and the gamma-ray beam pathlength through the sample are included in the data files. Two adjustments to the raw data have been made:

1. Data from 72.435 to 73.450 m were accidentally deleted during core scanning. Density data in this region were reconstructed from optical brightness data obtained from the National Ice Core Laboratory (NICL) Optical Imaging System. As such, the uncertainty associated with the reconstructed density was estimated to be five times larger than normal MADGE data.

2. Density data from 114.1 to 149.0 m were translated down by 0.011 g/cm^3 to match the densification trend observed both above and below this point, and to match the densities reported by J. Fitzpatrick in this region using iso-octane methods. All of the cores in this region were stored and transported to the University of Maine in the same ice core box, leading the researchers to believe it suffered improper storage temperatures at some point. For the same reason, density variability may also be reduced from its natural state in this section.

Final note: The researchers hypothesize that the uniformly high density region from 0 to 1.5 m depth is due to human-induced drifting at the drill site during the year prior to actually drilling WDC06A.

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Instruments
Table 6. Instruments
Data Type Instrument
Partical Concentration Klotz Abakus flow-through laser particle detector
Electrical Conductivity Amber Science flow-through conductivity meter
Density Automated gamma-ray density gauge
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References and Related Publications

Contacts and Acknowledgments

Dr. Karl Kreutz
Climate Change Institute 
University of Maine 
236 Sawyer Hall
Orono, Maine 04469
USA

Bess Koffman
University of Maine
236 Sawyer Hall
Orono, Maine 04469
USA 

Daniel Breton
Climate Change Institute 
University of Maine 
1 Sawyer Lab Annex 
Orono, Maine 04469 
USA

Dr. Gordon Hamilton
Climate Change Institute
University of Maine 
4 Sawyer Lab Annex 
Orono, Maine 04469
USA

Acknowledgements: 

This research was funded by National Science Foundation (NSF) Office of Polar Programs (OPP) grant number 0636740.

Document Information

DOCUMENT CREATION DATE

3 November 2011

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