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Data Set ID:
NSIDC-0334

Airborne Laser Altimetry of the Thwaites Glacier Catchment, West Antarctica, Version 1

This data set includes airborne altimetry collected over the catchment and main trunk of Thwaites Glacier, one of Antarctica's most active ice streams.

Geographic Coverage

Spatial Coverage:
  • N: -75, S: -80, E: -95, W: -130

Spatial Resolution: Not Specified
Temporal Coverage:
  • 10 December 2004 to 29 January 2005
Temporal Resolution: Not specified
Parameter(s):
  • Glaciers/Ice Sheets > Glacier Elevation/Ice Sheet Elevation
  • Glaciers/Ice Sheets
  • Glaciers/Ice Sheets > Glacier Topography/Ice Sheet Topography
  • Glaciers/Ice Sheets > Ice Sheets
  • Snow/Ice
Platform(s) AIRCRAFT, FIELD SURVEYS
Sensor(s): ALTIMETERS, GPS, INS
Data Format(s):
  • ASCII Text
Version: V1
Data Contributor(s): Duncan Young, Scott Kempf, Donald Blankenship, John Holt, David Morse

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.

Young, D. A., S. D. Kempf, D. D. Blankenship, J. W. Holt, and D. L. Morse. 2008. Airborne Laser Altimetry of the Thwaites Glacier Catchment, West Antarctica, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5HD7SK8. [Date Accessed].

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Detailed Data Description

This data set includes airborne altimetry collected over the catchment and main trunk of Thwaites Glacier, one of Antarctica's most active ice streams. The airborne altimetry comprises 35,000 line-kilometers sampled at 20 meters along track. The full data set has an internal error of ±20 cm; a primary subset has an error of ±8 cm. We find a +20 cm bias with Geoscience Laser Altimeter System data over a flat interior region. These data will serve as an additional temporal reference for the evolution of Thwaites Glacier surface, as well as aid the construction of future high resolution Digital Elevation Models (DEM).

Format

Space delimited ASCII with ten columns; 43 Mb after gzip compression. 
Time(J2000 seconds) 
Longitude 
Latitude 
ps71 meters eastings 
ps71 northings 
elevation (WGS-84) 
Project 
System 
Transect 
Quality Flag 
Project indicates the project flown; most of these lines were THW; Unplanned transit flights fell under ASE1. System indicates the onboard acquisition system used; this is SJB0 for all of this data. Transect is the name of the flown line; normally all three terms are used to designate a flight line to maintain uniqueness among all seasons.

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File Naming Convention
File name
File Size
Description
.dbase.gz 43 MB compressed file
.txt 161 MB space-delimited ASCII
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File Size

161 MB ASCII
43 MB after gzip compression

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Spatial Coverage

Thwaites Glacier, Smith Glacier and Haynes Glacier, West Antarctica

Southernmost Latitude: 80 S
Northernmost Latitude: 75 S
Westernmost Longitude: 95 W
Easternmost Longitude: 130 W

Spatial Resolution

1 cm resolution in elevation, 20 meters along track

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Temporal Coverage

Collection period: 10 December 2004 through 29 January 2005 (Summer only)

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Parameter or Variable

Ice sheet elevation

Parameter Description

Ice sheet elevation via laser altimetry

Sample Data Record

Time(J2000 seconds)
Longitude
Latitude
ps71 meters eastings
ps71 northings
Elevation (WGS-84)
Project
System
Transect
Quality Flag
157472167.727700
-124.793463
-76.072357
-1248629.329000
-867608.728800
2184.409372
THW
SJB0
X03a
PRIMARY
157472168.020600
-124.793730
-76.072517
-1248610.745000
-867604.463600
2184.638830
THW
SJB0
X03a
PRIMARY
157472168.312200
-124.794007
-76.072676
-1248592.173000
-867600.505700
2184.631137
THW
SJB0
X03a
PRIMARY
157472168.603500
-124.794287
-76.072833
-1248573.759000
-867596.735300
2184.690533
THW
SJB0
X03a
PRIMARY
157472168.892800
-124.794545
-76.072990
-1248555.635000
-867592.475200
2184.857183
THW
SJB0
X03a
PRIMARY
157472169.181900
-124.794771
-76.073149
-1248537.813000
-867587.396600
2184.900682
THW
SJB0
X03a
PRIMARY
157472169.471000
-124.795006
-76.073307
-1248519.964000
-867582.591300
2184.871665
THW
SJB0
X03a
PRIMARY
157472169.761600
-124.795253
-76.073466
-1248501.800000
-867577.967100
2185.149318
THW
SJB0
X03a
PRIMARY
157472170.052400
-124.795530
-76.073626
-1248483.190000
-867573.967300
2185.194623
THW
SJB0
X03a
PRIMARY
157472170.341700
-124.795796
-76.073787
-1248464.514000
-867569.589200
2185.277740
THW
SJB0
X03a
PRIMARY
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Software and Tools

Quality Assessment

The Quality Flag (either 'PRIMARY' or 'SECONDARY') indicates whether the root mean square (RMS) crossovers values of the data was low enough to allow it to influence other data during leveling, or whether it should attempt to level to other data.

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Data Acquisition and Processing

Sensor or Instrument Description

A Riegl LD90-3HiP nadir pointing distance ranger, sampling at 3.5 Hz, was used to collect the range data; K&RS, a differential dual carrier phase method, and kinematic GIPSY, a single receiver dual carrier phase method, was used to reduce the GPS positioning at 2 Hz and 1 Hz respectively. Trimble 5700 and Ashtech Z-Surveyor receivers on both the aircraft and at the bases were used for GPS acquisition. A Litton 92 ring laser gyro inertial navigation system (INS) provided attitude data, with a quoted angular resolution of 0.05˚.

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Data Acquisition Methods

These data were collected on a DHC-8 Twin Otter flown out of camps in the Pine Island Glacier Catchment and on the Ross-Amundsen Sea Divide in 2004-05. Typical line spacing was 15 kilometers. The aircraft typical ground speed was 70 meters per second.

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Derivation Techniques and Algorithms

Error Sources

Data gaps are due to clouds, excessively rough terrain (i.e. crevasses, rock) and poor GPS solutions. Lines lacking at least three cross overs were dropped as quality assessment was difficult. These data have not been tide corrected.

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References and Related Publications

Contacts and Acknowledgments

Investigator(s)

Duncan A.Young 
University of Texas at Austin 
Jackson School of Geosciences, Institute for Geophysics 
J.J. Pickle Research Campus Bldg. 196
10100 Burnet Road (R2200) 
Austin, TX 78758-4445 USA

Scott D. Kempf
University of Texas at Austin 
Jackson School of Geosciences, Institute for Geophysics 
J.J. Pickle Research Campus Bldg. 196
10100 Burnet Road (R2200) 
Austin, TX 78758-4445 USA

Donald D. Blankenship
University of Texas at Austin 
Jackson School of Geosciences, Institute for Geophysics 
J.J. Pickle Research Campus Bldg. 196
10100 Burnet Road (R2200) 
Austin, TX 78758-4445 USA

John W. Holt
University of Texas at Austin 
Jackson School of Geosciences, Institute for Geophysics 
J.J. Pickle Research Campus Bldg. 196
10100 Burnet Road (R2200) 
Austin, TX 78758-4445 USA

David L. Morse
University of Texas at Austin 
Jackson School of Geosciences, Institute for Geophysics 
J.J. Pickle Research Campus Bldg. 196
10100 Burnet Road (R2200) 
Austin, TX 78758-4445 USA

Acknowledgements: 

This research was supported by National Science Foundation (NSF) Office of Polar Programs (OPP) grant 0230197 awarded to John Holt, Donald Blankenship and David Morse, OPP grant 0636724 awarded to Blankenship and Holt, the G. Unger Vetlesen Foundation and the Jackson School of Geosciences.

Document Information

Document Creation Date

March 2008

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