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Data Set ID:
NSIDC-0336

Antarctic Subglacial Lake Classification Inventory, Version 1

This data set is an Antarctic radar-based subglacial lake classification collection, which focuses on the radar reflection properties of each given lake.

Geographic Coverage

Spatial Coverage:
  • N: -70, S: -90, E: 15, W: -160

Spatial Resolution: Not Specified
Temporal Coverage:
  • 1 December 1998 to 28 February 2001
Temporal Resolution: Not specified
Parameter(s):
  • Glaciers/Ice Sheets
  • Glaciers/Ice Sheets > Glacier Thickness/Ice Sheet Thickness
  • Glaciers/Ice Sheets > Glacier Topography/Ice Sheet Topography
  • Glaciers/Ice Sheets > Ice Sheets
  • Snow/Ice
Platform(s) FIELD INVESTIGATION, FIELD SURVEYS
Sensor(s): IMAGING RADAR SYSTEMS, RADAR
Data Format(s):
  • Microsoft Excel
Version: V1
Data Contributor(s): Donald Blankenship, John Holt, Sasha Carter

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.

Blankenship, D. D., S. P. Carter, J. W. Holt, D. L. Morse, M. E. Peters, and D. A. Young. 2009. Antarctic Subglacial Lake Classification Inventory, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5CN71VX. [Date Accessed].

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Detailed Data Description

This data set is an Antarctic radar-based subglacial lake classification collection, which focuses on the radar reflection properties of each given lake. The Subglacial lakes are separated into four categories specified by radar reflection properties. Additional information includes: latitude, longitude, length (in kilometers), hydro-potential (in meters), bed elevation (in meters above WGS84), and ice thickness (in meters).

Format

The data set is in Microsoft Excel (.xls) format viewable with spreadsheet software. A coverage map is available in TIF 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/blankenship_nsidc_0336/ directory. The directory contains four files: an Excel spreadsheet, lake_detect.xls, a Tagged Image File Format (TIF) image, a readme file, and a supplementary Portable Document Format (PDF) file. 

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File Division

Within the lake_detect.xls file, there are 12 sheets defined by lake type and location. For more information on the lake defining algorithms, please see the article Radar-Based Subglacial Lake Classification in Antarctica on the Geochemistry, Geophysics, Geosystems Web site. A PDF of the article is also available via FTP.

The 12 sheets within the Excel file are named according to their lake type and region. The following table describes the naming system for sheets within the lake_detect.xlsfile

Example laketype.xls sheet names:

definite_WLK
dim_PPT
fuzzy_LVS
indistinct_PPT

Where:

Table 1. Definition of naming variables in the lake_detect.xls File
Variable Definition
Lake Type
definite brighter than surroundings by at least 2 dB, specular across at least 5% of its extent, maintains a reflection coefficient of -10 dB or greater across at least 5% of its extent
dim specular and brighter than surroundings, but lack the absolute reflectivity of definite lakes; estimated reflection coefficient falls well below -10 dB
fuzzy high absolute and relative reflection coefficients, but not specular
indistinct specular, but not brighter than surroundings.
Location
WLK Wilkes Basin-Dome C
LVS Lake Vostok Region
PPT Mercer Ice Stream-South Pole
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File Size

Excel File, 68 KB; TIF image file 7.1 MB

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Spatial Coverage

Study locations were in East Antarctica, including the Mercer Ice Stream, Lake Vostok Region, and Wilkes Basin-Dome C.

Southernmost Latitude: 90° S
Northernmost Latitude: 70° S
Westernmost Longitude: 180° W
Easternmost Longitude: 180° E

Spatial Coverage Map

map of coverage, east antarctica
Image from Carter, S. P. et. al., 2007

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Temporal Coverage

Source data used to compile this data set were collected between 1998 and 2001. For more information, please see the references section of this document.

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Parameter or Variable

Parameters include location of lakes as geographic coordinates, lake length, hydro-potential, bed elevation in meters above WGS84, and ice thickness. The Wilkes Basin-Dome C (WLK) spreadsheet also includes the lake number from the Siegert, et al inventory in 2005.

The following table describes the columns in the data files:

Table 3. Description of Columns in the lake_detect.xls file
Column
Description
Latitude/Longitude Lake location in geographic coordinates
Length Lake length in kilometers
Hydro-potential Hydraulic potential, also called hydraulic head, is the sum of the elevation of the water body and the fluid pressure. In this case hydraulic head is equal to the elevation plus ice thickness multiplied by density contrast of ice relative to water or 0.917h_ice + z_bed.
Bed Elevation Bed elevation, measured as meters above World Geodetic System 84 (WGS84), a standard coordinate frame for the Earth
Ice Thickness Ice thickness above the lake feature, measured in meters, ±standard error
Number If applicable, inventory number from Siegert et al., 2005
Notes Investigator's notes, generally related to lake location
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Sample Data Record

The following example shows sample data from the definite_WLK spreadsheet in the lake_detect.xls file

Latitude
Longitude
Length (km)
Hydro-potential (m)
Bed Elevation 
(m above WGS84)
Ice Thickness (m)
Number (from Siegert et al 2005 Inventory)
Notes
-74.07
125.02
35
2845
-890
4072 ±47
6
Concordia got broken up into two overlapping lakes
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Software and Tools

Data are accessible using standard spreadsheet software.

Volume

The data set is approximately 60KB. Supplementary files are approximately 11MB.

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Data Acquisition and Processing

The Antarctic Subglacial Lake Classification Inventory lists the locations and categories of lakes in East Antarctica. For more information on data processing, please see the article Radar-Based Subglacial Lake Classification in Antarctica on the Geochemistry, Geophysics, Geosystems Web site. A PDF of the article is also available via FTP.

Sensor or Instrument Description

This data set was developed using laser and radar altimetry measurements, as well as measurements of gravitational and magnetic fields.

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Data Source

Source data was obtained from the University of Texas Institute for Geophysics data set for radio echo sounding in East Antarctica. (Holt, et. al.Siegert et. al.)

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Derivation Techniques and Algorithms

A lake detection algorithm was used to identify and categorize four major "lake" types using digital ice-penetrating radar data. For details on the algorithm, please see the article Radar-Based Subglacial Lake Classification in Antarctica on the Geochemistry, Geophysics, Geosystems Web site.

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References and Related Publications

Contacts and Acknowledgments

Donald D. Blankenship
University of Texas Institute for Geophysics 
John A. and Katherine G. Jackson School of Geosciences, 
The University of Texas at Austin

Sasha P. Carter
Scripps Institution of Oceanography, UCSD
9500 Gilman Drive
La Jolla CA, 92093
Mail Code: 0225

John W. Holt
University of Texas Institute for Geophysics
John A. and Katherine G. Jackson School of Geosciences
University of Texas at Austin
Phone: 512-471-0487

Acknowledgements: 

This research was funded by the National Science Foundation under Cooperative Agreement OPP 91-19379 and OPP 93-19379, as well as NSF grant OPP 99-11617.

Document Information

Document Creation Date

6 February 2009

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

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