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Data Set ID:
NSIDC-0282

GPR and GPS Data: Characteristics of Snow Megadunes and their Potential Effects on Ice Core Interpretation, Version 1

This data set contains Ground Penetrating Radar (GPR) data showing surface morphology and internal layering structure along with Global Positioning System (GPS) data collected within an area of 60 km2.

Geographic Coverage

Spatial Coverage:
  • N: -80.5304, S: -80.7802, E: 126.0302, W: 124.0218

Spatial Resolution: Not Specified
Temporal Coverage:
  • 3 January 2004 to 7 January 2004
  • 5 December 2002
Temporal Resolution: Not specified
Parameter(s):
  • Glaciers/Ice Sheets > Firn
  • Geomorphology > Glacial Landforms/Processes
  • Glaciers/Ice Sheets > Ice Sheets
  • Snow/Ice > Snow Stratigraphy > Internal Layering
  • Snow/Ice > Snow Stratigraphy
Platform(s) GPS, GROUND-BASED OBSERVATIONS
Sensor(s): GPR, GPS
Data Format(s):
  • Microsoft Excel
  • ASCII Text
  • JPEG
Version: V1
Data Contributor(s): Ted Scambos, Rob Bauer

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.

Scambos, T. and R. Bauer. 2006. GPR and GPS Data: Characteristics of Snow Megadunes and their Potential Effects on Ice Core Interpretation, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5Q23X5F. [Date Accessed].

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Detailed Data Description

This data set contains Ground Penetrating Radar (GPR) data showing surface morphology and internal layering structure along with Global Positioning System (GPS) data collected within an area of 60 km<sup>2</sup>.

The Antarctic megadune research was conducted during two field seasons, one in November 2002 and the other in December 2003 through January 2004. The megadune field site is located on the East Antarctic Plateau, southeast of Vostok station. The objectives of this multi-facetted research are to determine the physical characteristics of the firn across the dunes including typical climate indicators such as stable isotopes and major chemical species and to install instruments to measure the time variation of near-surface wind and temperature with depth, to test and refine hypotheses for megadune formation. It is important to improve our current understanding of the megadunes because of their extreme nature, their broad extent, and their potential impact on the climate record. Megadunes are a manifestation of an extreme terrestrial climate and may provide insight on past terrestrial climate or on processes active on other planets.

Snow megadunes are undulating variations in accumulation and surface texture with wavelengths of 2 to 5 km and amplitudes up to 5 meters. The features cover 500,000 km<sup>2</sup> of the East Antarctic plateau, occurring in areas of moderate regional slope and low accumulation on the flanks of the ice sheet between 2500 and 3800 meters elevation. Landsat images and aerial photography indicate the dunes consist of alternating surfaces of glaze and rough sastrugi, with gradational boundaries. This pattern is oriented perpendicular to the mean wind direction, as modeled in katabatic wind studies. Glaze surfaces cover the leeward faces and troughs; rough sastrugi cover the windward faces and crests. The megadune pattern is crossed by smooth to eroded wind-parallel longitudinal dunes. Wind-eroded longitudinal dunes form spectacular 1-meter-high sastrugi in nearby areas.

File Size

File sizes range from 1 KB to 16 MB.

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Spatial Coverage

Southernmost Latitude: 80.7802° S
Northernmost Latitude: 80.5304° S
Westernmost Longitude: 124.0218° E
Easternmost Longitude: 126.0302° E

Thumbnail of the megadune traverses Click on the thumbnail to view the regional GPR/GPS traverses (JPEG file, 120 KB).

Spatial Resolution

Investigators surveyed approximately 60 kilometers in distance during their traverses.

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Temporal Coverage

GPS data were collected on 5 December 2002 and on various dates from 3 January 2004 through 17 January 2004.GPR data were collected on 7 January 2004 through 10 January 2004. The profiles extend to approximately 50 m below the surface, a depth that corresponds to approximately 2,000 years before present.

Temporal Resolution

GPS data were recorded every 15 seconds during a traverse.

GPR samples were collected at 100 MHz and 250 MHz. For the resulting profiles, each dune layer represents approximately 400 years.

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Parameter or Variable

Parameter Description

Dunes accrete into the wind and form stacked but tilted sequences that are approximately 10 m to 15 m thick with "glaze" areas that represent accumulation hiatuses of approximately 250 years.

Parameter Range

Dune structure is seen up to 60 m below the surface. This is confirmed by density profiles from ice cores.

Sample Image

sample image

Click on the thumbnail to view the radar profile (GIF file, 288 KB) collected on a traverse from the S1 pole to the N1 pole.

GPS data are viewable with a text editor or Microsoft Excel. GPR data can be viewed with image viewing software capable of opening JPEG files that are up to 16 MB in size.

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Software and Tools

Volume

The entire data set is 37.7 MB.

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Software and Tools

GPS data are viewable with a text editor or Microsoft Excel. GPR data can be viewed with image viewing software capable of opening JPEG files that are up to 16 MB in size.

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Data Acquisition and Processing

Sensor or Instrument Description

GPR:

  • Used RAMAC System
  • 100 MHz shielded
  • 250 MHz shielded
  • 32 stacks, ~700 - 1024 nsec
  • 1 stacked trace/sec (1.35 sec)
  • 60 km+ surveyed

GPS:

  • Used Trimble 4400i, kinematic Base station at MGD Camp pole
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Derivation Techniques and Algorithm

MATLAB code was used to process radar data and correct for surface elevation and density. Time of acquisition was converted to distance.

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Processing Steps

GPR Post-processing:

  • Removed local mean trace (200 traces running)
  • Normalized by the mean absolute magnitude of mean the mean trace
  • Smoothed by averaging traces (3-trace running mean)
  • Corrected time-depth-density using density from main core
  • Corrected for topography and converted time to distance using GPS profiles
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References and Related Publications

Contacts and Acknowledgments

Ted Scambos 
National Snow and Ice Data Center 
449 UCB, University of Colorado 
Boulder, CO 80309-0449

Rob Bauer 
National Snow and Ice Data Center 
449 UCB, University of Colorado 
Boulder, CO 80309-0449

Acknowledgements: 

This research was supported by the National Science Foundation (NSF) Office of Polar Programs (OPP) grant OPP-0125276.

Document Information

Document Creation Date

May 2006

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