Data Set ID:
NSIDC-0605

C-axis Fabric from Physical Properties Samples of the WAIS Divide Ice Core, Version 1

This data set contains c-axis fabric measurements and grain area from the physical properties samples taken from the main West Antarctic Ice Sheet (WAIS) Divide ice core, WDC06A , Antarctica.

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NSIDC does not archive these data.

Geographic Coverage

Parameter(s):
  • Ice Core Records
  • Snow/Ice > Ice Fabric
Spatial Coverage:
  • N: -79.467, S: -79.467, E: -112.085, W: -112.085

Spatial Resolution:
  • 140 to 3504
Temporal Coverage:
  • 1 August 2011 to 1 October 2014
Temporal Resolution: Varies
Data Format(s):
  • Microsoft Excel
  • Bitmap (.bmp)
  • JPEG
  • ASCII Text
Platform(s) Laboratory
Sensor(s): ACFA
Version: V1
Data Contributor(s): Donald Voigt, Richard Alley, Joan Fitzpatrick
Please contact the data provider for the correct Data Citation for this data set.

Literature Citation

As a condition of using these data, we request that you acknowledge the author(s) of this data set by referencing the following peer-reviewed publication.

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Detailed Data Description

This data set contains c-axis fabric measurements and grain area from the physical properties samples taken from the main WAIS Divide ice core, WDC06A , Antarctica ( Figure 1). The sample interval was 20 m and represents samples from 140 m depth to the bottom of the core at 3405 m depth. The c-axis measurements were obtained from 10 cm by 10 cm thin sections on the automated c-axis analyzer designed and built by Larry Wilen (Wilen 2003).

WAIS Divide Map
Figure 1. WAIS Divide Map
Format

Data are provided in tab-delimited text (.txt), and images are in jpeg (.jpg) and bitmap (.bmp) formats. A database of analyzed sections is in Microsoft Excel (.xls) 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/nsidc0605_voigt/ directory. Within this directory, there are 83 folders, one for each nominal depth, containing seven to eight files each and one Microsoft Excel spreadsheet, Database of Analyzed Sections.xls. See Table 1 for descriptions of the files within each folder and the database spreadsheet.

Table 1. File Descriptions
File Type Format Description
Information .txt contains date and time the section was run for this analysis, the scaling factor of the image (mm/pixel), the actual depth of the sample, and any other special information about the sample
C-Axes .txt contains the grain number, theta, phi and the R² value for the grain. Grains for which the program was unable to calculate a c-axis are labeled as "grain not analyzable." The R² value is a value for the quality of the measurement of a particular grain.
Area .txt contains the area of each grain in square pixels. The mm/pixel calibration can be used to determine the area in mm2
Edge File Image .bmp image of the edge file used to pick grains
Labeled Image .bmp image of the thin section with the grains numbered
Unlabeled Image .jpg an unlabeled image of the thin section
Horizontal Schmidt Plot Image .jpg image of the horizontally rotated thin section, unfiltered by R²
Schmidt Plot Image .jpg image of vertically rotated thin section around the core's axis so the major axis of the data set is parallel to X. The value for rotation is given in the table, Database of Analyzed Sections.xls, as azimuth
Database of Analyzed Sections .xls provides the section number, top depth and bottom depth, the azimuth and the eigenvalues of each section
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File Naming Convention

This section explains the file naming convention used for the three text (.txt) files in this data set with examples.

Example File Names:
1264 Section Info.txt
1264 area.txt
1264 c-axes.txt

#### xxxxxxx.txt

Refer to Table 2 for the valid values for the file name variables listed above.

Where:

Table 2. Text File Naming Convention
Variable Description
#### Sample number
xxxxxxx

indicates the type of information for each section:
#### Section info.txt includes date, time, scaling factor, depth, etc. of the sample;
#### area.txt includes area of each grain;
#### c-axes.txt includes grain number, theta, phi and the R² value

This section explains the file naming convention used for the two bitmap image files (.bmp) in this data set with examples.

Example File Names:
1264 edges.bmp
1264 labeled picture.bmp

#### edges/labeled picture(or picture).bmp

Refer to Table 3 for the valid values for the file name variables listed above.

Where:

Table 3. Bitmap File Naming Convention
Variable Description
#### Sample number
edges image of the edge file used to pick grains
labeled picture/picture image of the thin section with the grains numbered

This section explains the file naming convention used for the vertical Schmidt Plot image files in this data set with an example.

Example File Names:
SP of 15.05 WDC06A 1264 VTS.JPEG

SP of xx.xx WDC06A #### VTS.jpeg(or jpg)

Refer to Table 4 for the valid values for the file name variables listed above.

Where:

Table 4. Vertical Schmidt Plot File Naming Convention
Variable Description
SP of Schmidt plot of
xx.xx time stamp (24-hour clock) of sample
WDC06A WAIS Divide Core number
#### sample number
VTS Vertical Thin Section

This section explains the file naming convention used for the horizontal Schmidt Plot image files in this data set with an example.

Example File Names:
1264 horizontal SP.jpg

#### horizontal SP.jpg (or jpeg)

Refer to Table 5 for the valid values for the file name variables listed above.

Where:

Table 5. Horizontal Schmidt PlotFile Naming Convention
Variable Description
#### sample number
horizontal direction of the sample to the X-axis
SP Schmidt plot

This section explains the file naming convention used for the unlabeled image files in this data set with an example.

Example File Names:
1264 VTS unlabeled picture.JPEG

#### VTS unlabeled picture.jpg (or jpeg)

Refer to Table 6 for the valid values for the file name variables listed above.

Where:

Table 6. Unlabeled Images File Naming Convention
Variable Description
#### sample number
VTS Vertical Thin Section
unlabeled picture image of grains without numbers
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File Size

Data files range from 1 KB to 973 KB.

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Spatial Coverage

WAIS Divide, Antarctica: 79.467° S, 112.085° W

Spatial Resolution

Core depths range from 140 m - 3405 m with core samples 10 cm long taken every 20 m

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Temporal Coverage

Data collected 01 August 2011 to 01 October 2014
Data extend from 67748 cal yr BP to 480 cal yr BP

Temporal Resolution

Temporal resolution for the data varies.

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Parameter or Variable

Ice fabric (c-axis angle measurements)
Ice core records

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Software and Tools

The data can be accessed using any text editor, image editing software, and Microsoft Excel.

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Data Acquisition and Processing

Derivation Techniques and Algorithms

Processing Steps

Fabric was measured on the automated c-axis fabric analyzer located at Penn State University, designed and built by Larry Wilen. Raw data is in the form of multiple images of the ice thin section taken at defined angles under cross polarized light. The images are analyzed to determine position of the extinction minimum of each grain within the thin section, this being the orientation of the c-axis of that grain. During processing, the area of each analyzed grain is also measured.

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Sensor or Instrument Description

Automatic C-Axis Fabric Analyzer

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References and Related Publications

Contacts and Acknowledgments

Donald E. Voigt
Penn State University
Department of Geosciences
209 Deike Bldg
University Park, PA 16802

Richard B. Alley
Penn State University
Department of Geosciences
517B Deike Bldg
University Park, PA 16802

Joan J. Fitzpatrick
Geosciences and Environmental Change Science Center
USGS
Box 25046, MS 980
Denver, CO 80225

Acknowledgments: 

This research was supported by NSF Antarctic Earth Sciences Grant Number ANT-10-43528.

Document Information

DOCUMENT CREATION DATE

December 2014

No technical references available for this data set.
No FAQs or How Tos available for this data set.

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