Digital Imaging for Siple Dome Ice Core Analysis, Antarctica

Summary

This data set contains high-resolution digital images of thin and thick sections cut from the 1003 meter Siple Dome A main ice core. The images are useful for crystal size and orientation analysis and bubble size, shape, distribution, and number density determinations. The data set contains several generations of images, taken between June 1998 and May 2005. An accompanying spreadsheet contains creation date information for each file.

The data are available via FTP in Adobe Photoshop Document (.psd), and Tagged Image File (.tif) formats. Additional information is provided as a Microsoft Excel (.xls) spreadsheet.

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, data set title, publisher: NSIDC, and digital media.

Fitzpatrick, Joan, Richard Alley, and Matthew Spencer. 2009. Digital Imaging for Siple Dome Ice Core Analysis, Antarctica. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5XG9P2G.

Overview Table

Category	Description
Data format	Tagged Image File (.tif) Adobe Photoshop Document (.psd)
Spatial coverage and resolution	Southernmost Latitude: 81°40'S Northernmost Latitude: 81°40'S Westernmost Longitude: 148°49'W Easternmost Longitude: 148°49'W
Temporal coverage and resolution	Ice core drilling was completed in 1999. Images were obtained between June 1998 and May 2005.
File naming convention	SDMA240-123VTS1.tif SDMA240-123HB.psd SDMA_file_creation_dates.xls
File size	The data set is a total of 1.42 GB.
Parameter(s)	Images of thin and thick ice core sections, cut vertically and horizontally.
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

Investigators

Dr. Joan Fitzpatrick
MS-980 Box 25046, DFC
United States Geological Survey
Denver, CO 80225
USA

Dr. Richard B. Alley
Department of Geosciences
306 Deike Building
Pennsylvania State University
University Park, PA 16802
USA

Dr. Matthew Spencer
Department of Geology and Physics
Lake Superior State University
650 W. Easterday Ave.
Sault Ste. Marie, MI 49783
USA

Technical Contact

Acknowledgements

This research was supported by National Science Foundation (NSF) Office of Polar Programs (OPP) grant 9615554 and the U.S. Geological Survey Earth Surface Dynamics Program.

2. Detailed Data Description

Format

Data are available in Adobe Photoshop Document (.psd), and Tagged Image File (.tif) formats. The SDMA_file_creation_dates.xls spreadsheet contains detailed information about each image file, including the date the photo was acquired, the image resolution in pixels per inch (ppi), and the stratigraphic image orientation.

File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/fitzpatrick_nsidc_0413/SDMA_core_images/ directory. Within this directory, there SDMA_psd directory contains the data set in .psd format. The SDMA_tif directory contains all the ice core images as.tif files. The directory also contains a readme file in .txt format, and a Microsoft Excel spreadsheet with creation date information.

File Naming Convention

Files are named according to the following convention and as described in Table 1:

SDMAddd-dddtttN.bin

Where:

Table 1. File Naming Convention

Variable	Description
SDMA	Siple Dome "A" Ice Core
ddd-ddd	Depth of sample, in meters. The dash corresponds to a decimal point. For example, 240-123 corresponds to 240.123 meters
ttt	Type of section: HB: Horizontal Bubble Section VB: Vertical Bubble Section HTS: Horizontal Thin Section VTS: Vertical Thin Section
N	Sequence number: Presence of a sequence number indicates that the same ice core section was photographed multiple times under slightly different magnification or rotation. Absence of a sequence number means that the photograph is unique.
.bin	File extension: .tif or .psd

Example: SDMA240-123VTS1 is first in a series of vertical thin section images, from the section at 240.123 meters of the Siple Dome A ice core.

File Size

Files range in size from 490 KB to 20550 KB.

Spatial Coverage

Photographs are from sections of the 1003-meter deep main ice core from Siple Dome A. The core drilling was completed in 1999.

Southernmost Latitude: 81°40'S
Northernmost Latitude: 81°40'S
Westernmost Longitude: 148°49'W
Easternmost Longitude: 148°49'W

Temporal Coverage

The ice core drilling was completed in 1999. Photographs were taken between June 1998 and September 1999.

Parameter or Variable

This data set contains high-resolution digital images of ice core sections from the Siple Dome A ice core.The data set includes thin and thick (bubble) sections, cut both vertically and horizontally. Depth of the images range from 153 meters to 936 meters deep. The ice core was 1003 meters deep. Each image includes a ruler for size reference.

Sample Data Records

 

Quality Assessment

The data set contains several generations of images. The best images are those acquired on sections cut in the field during drilling operations (completed in January, 1999). These sections were completed in the field to a nominal depth of 560 meters although the final total depth of the core was 1003 meters. Below 560 meters ice became too brittle to handle without incurring significant damage and no further attempt to cut it in the field was made.

Later efforts at cutting additional sections to complete analyses to the bottom of the core continued to be challenging due to the failure of the core to significantly relax during the intervening years. The extraordinary mechanical fragility of this core remains a physical hallmark even ten years after its recovery. A high percentage of bubbles in the core opened stress-relief cracks, complicating the size analysis (though not the number of density determinations). These annular cracks are apparent in the bubble section photographs taken below 400 meters in the year 2000 and later, as are large, through-going cracks created while cutting the sections from the main body of the core after it was returned from Antarctica to the National Ice Core Laboratory in Denver, Colorado, USA.

Image Quality Comparison

Comparison of Image Quality in Ice Core Bubble Images

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The data set is a total of 1.42 GB.

Software and Tools

Data are accessible using image processing software.

Related Data Collections

• Ice Fabric Characteristics: Siple Dome, A Core
• Digital Images of Thin Sections from Siple Dome

4. Data Acquisition and Processing

Theory of Measurements

Thick (bubble) sections were photographed in 90 degree darkfield illumination using a circular light source at the level of the section. Thin sections (grain analysis) were photographed in cross-polarized, transmitted light. A high-resolution scanning digital camera was utilized for all photography.

5. References and Related Publications

Diprinzio, C. L., L. A. Wilen, R. B. Alley, J. J. Fitzpatrick, M. K. Spencer, M. J. Gow. 2005. Fabric and texture at Siple Dome, Antarctica. Journal of Glaciology, Vol. 51, no. 173, pp. 281-290.

Spencer, M. K., R. B. Alley, and J. J. Fitzpatrick. 2006. Developing a bubble number-density paleoclimatic indicator for glacier ice. Journal of Glaciology, Volume 52, Number 178, pp. 358-364(7).

6. Document Information

Acronyms

The acronyms used in this document are listed in Table 2.

Table 2. Acronyms and Abbreviations

Acronym	Description
AGDC	Antarctic Glaciological Data Center
FTP	File Transfer Protocol
NSIDC	National Snow and Ice Data Center
PPI	Pixels per inch
PSD	Photoshop Document
TIF	Tagged Image File
URL	Uniform Resource Locator
XLS	Microsoft Excel file extension

Document Creation Date

10 August 2009

Document URL

http://nsidc.org/data/docs/agdc/nsidc0413_fitzpatrick/index.html