The data set comprises the mean grain sizes at the sampled depths derived from vertical thin sections and reflects the final WDC 06A timescale.
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DOWNLOADING DATA VIA FTP
Data can be downloaded through a Web browser or command line via FTP. When using a Web browser, the FTP link first directs you to an Optional Registration Form that if filled out, will allow you to receive notifications about updates or processing changes related to that specific data set. After completing the Optional Registration Form, the FTP directory becomes available. For additional help downloading data through an FTP client, go to the How to access data using an FTP client support page.
WDC 06A Mean Grain Size Data, Version 1
Geographic Coverage
Spatial Coverage: |
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Spatial Resolution: |
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Temporal Coverage: |
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Temporal Resolution: | Not specified |
Parameter(s): |
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Platform(s) | Laboratory |
Sensor(s): | DSLR |
Data Format(s): |
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Version: | V1 |
Data Contributor(s): | Joan Fitzpatrick, Eric Cravens |
Metadata XML: | View Metadata Record |
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.
Fitzpatrick, J. and E. D. Cravens. 2016. WDC 06A Mean Grain Size Data, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5MC8X08. [Date Accessed].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.
Fitzpatrick, J. et al. 2014. Physical properties of the WAIS Divide ice core, Journal of Glaciology. 60. 1181-1198. http://dx.doi.org/10.3189/2014JoG14J100
The data set comprises the mean grain sizes at the sampled depths derived from vertical thin sections and reflects the final WDC 06A timescale.
Detailed Data Description
The mean grain areas are based on the processing and analysis of 240 pixel/inch native resolution, 8-bit, RGB images. Users are cautioned that the utility of the mean value is limited. It is provided in this data set to facilitate comparison with older cores for which only the mean grain sizes are provided in the literature. Grain size distributions for the WAIS Divide core are not generally lognormal and the mean-normalized populations are not Gaussian. Refer to the Grain Size Full Population Dataset from WDC06A Core data set for the full grain size information.
The data are in Microsoft Excel (.xls) format.
Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0656_fitzpatrick directory. Within this directory, there is one file, WDC 06A Mean Grain Size.xlsx. The data file consists of two worksheets: "metadata"and "data". Refer to Table 1 for a description of the columns in the "data" worksheet.
Column | Description |
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Nominal Depth (m) | Nominal core sample depth in meters |
True Top Depth (m) | True top depth in meters as determined by the field core processing line (cpl) over the depth interval 120 - 580 m, and the National Ice Core Laboratory (NICL) cpls below this depth |
Age before 1950 (yr) | Age in years before 1950 based on the WDC06A-3 timescale |
Mean Area VERT (mm2) | Arithmetic mean of all areas evaluated for all grains in the sample (mm2) |
Mean Equivalent Diameter VERT (mm) | Arithmetic mean of all equivalent diameters (the diameter of a circle with area equivalent to the area of a given analyzed grain) evaluated for all grains in the sample (mm) |
Mean Aspect Ratio (cm) | Arithmetic mean of all aspect ratios (maximum caliper dimension divided by minimum caliper dimension) evaluated for all grains in the sample (cm) |
Grain Count | Number of observations (i.e. grains) in the sample |
Refer to the "metadata" worksheet for more information.
The data file is 63 KB.
The WDC 06A ice core was extracted at the WAIS Divide, Antarctica at 79.28° S and 112.05°.
Spatial Resolution
Spatial resolution is every 20 m along the sample core from 120 m to 3405 m.
Temporal coverage for the data is 1 January 2008 to 30 August 2013. The paleo temporal coverage is 350 ybp to 67,309 ybp.
Parameter
The parameter for the data set is grain size.
Sample Data Record
Refer to Figure 1 for a sample of the data in the file (this image is only a partial representation of the rows in the file). Figure 2 is an image of the "metadata" worksheet.
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Software and Tools
The data are available via FTP.
To view the data, use Microsoft Excel.
Data Acquisition and Processing
The WAIS (West Antarctic Ice Sheet) Divide ice core was recovered over five drilling seasons in West Antarctica from 2007/08 to 2011/12, with an additional replicate coring season in 2012/13. The drillhole was completed to a total depth of 3405 m at the end of the 2011/12 season. Processing of the WAIS Divide main core was completed over the course of four summer processing lines in 2008, 2010, 2011 and 2012 at the US National Ice Core Laboratory, Denver, Colorado.
Processing Steps
The vertical thin sections (VTS) were examined using a Nikon D90 DSLR camera at 20 m intervals along the ice core. The images were assembled using Photoshop™, analyzed using Fovea Pro™ plug-ins for Photoshop™, and summarized using StatMac™ plug-in for Excel™. See Fitzpatrick 2013 for a detailed methodology.
References and Related Publications
Contacts and Acknowledgments
Dr. Joan J. Fitzpatrick
U. S. Geological Survey
Geosciences and Environmental Change Science Center
P.O. Box 25046, DFC, MS 980
Lakewood, CO 80225 U. S. A.
Eric D. Cravens
U. S. Geological Survey
Geosciences and Environmental Change Science Center
P.O. Box 25046, DFC, MS 980
Lakewood, CO 80225 U. S. A.
This research was supported by NSF Division of Polar Programs (PLR) Grant Number 0539578 and the U. S. Geological Survey Climate and Land Use Change Program.
Document Information
DOCUMENT CREATION DATE
25 February 2013
DOCUMENT REVISION DATE
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