IceBridge Riegl Laser Altimeter L2 Geolocated Surface Elevation Triplets

This data set contains surface range values for Antarctica and Greenland derived from measurements captured using the Riegl Laser Altimeter. The data were collected by scientists working on the Investigating the Cryospheric Evolution of the Central Antarctic Plate (ICECAP) project, which is funded by the National Science Foundation (NSF) and the Natural Environment Research Council (NERC) with additional support from NASA Operation IceBridge.

Operation IceBridge products may include test flight data that are not useful for research and scientific analysis. Test flights usually occur at the beginning of campaigns. Users should read flight reports for the flights that collected any of the data they intend to use. Check IceBridge campaign Flight Reports for dates and information about test flights.

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

Citing These Data

We kindly request that you cite the use of this data set in a publication using the following citation. For more information, see our Use and Copyright Web page.

Full Data Set:
Blankenship, Donald D., Duncan A. Young, Scott Kempf, Jason L. Roberts, Tas van Ommen, Rene Forsberg, Martin J. Siegert, Steven J. Palmer and Julian A. Dowdeswell. 2012, updated 2013. IceBridge Riegl Laser Altimeter L2 Geolocated Surface Elevation Triplets, [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. http://dx.doi.org/10.5067/JV9DENETK13E.

East Antarctica:
Blankenship, Donald D., Duncan A. Young, Scott D. Kempf, Jason L. Roberts, Tas van Ommen, Rene Forsberg and Martin J. Siegert. 2012, updated 2013. IceBridge Riegl Laser Altimeter L2 Geolocated Surface Elevation Triplets, [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. http://dx.doi.org/10.5067/JV9DENETK13E.

West Antarctica:
Young, Duncan A., Donald D. Blankenship, and Scott D. Kempf. 2012, updated 2013. IceBridge Riegl Laser Altimeter L2 Geolocated Surface Elevation Triplets, [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. http://dx.doi.org/10.5067/JV9DENETK13E.

Greenland:
Blankenship, Donald D., Duncan A. Young, Scott D. Kempf, Steven J. Palmer, and Julian A. Dowdeswell. 2012, updated 2013. IceBridge Riegl Laser Altimeter L2 Geolocated Surface Elevation Triplets, [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center. http://dx.doi.org/10.5067/JV9DENETK13E.

Overview

Platform

Basler BT-67

Sensor

Riegl Laser Altimeter

Spatial Coverage

Antarctica and Greenland

Spatial Resolution

25 m along track by 1 meter across track

Temporal Coverage

29 December 2008 to the present

Temporal Resolution

Seasonal

Parameters

Surface Range

Data Format

ASCII text (.txt) and XML (.xml)

Metadata Access

View Metadata Record

Get Data

FTP

1. Contacts and Acknowledgments

Investigator(s) Name and Title

Donald D. Blankenship, Duncan A. Young, and Scott D. Kemp
University of Texas at Austin
Institute for Geophysics
Austin, TX, 78759-8500

Jason L. Roberts and Tas van Ommen
Australian Antarctic Division
Kingston, Tasmania
and
Antarctic Climate and Ecosystems CRC
University of Tasmania
Hobart, Tasmania

Martin J. Siegert
Faculty of Natural Sciences
The Grantham Institute for Climate Change
Imperial College
London, UK

Rene Forsberg
National Space Institute
Danish Technical University
Copenhagen, Denmark

Steven J. Palmer
Department of Geography
University of Exeter
Exeter, UK

Julian A. Dowdeswell
Scott Polar Research Institute
University of Cambridge
Cambridge, UK

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

Acknowledgements

University of Texas Icebridge altimetry data was sponsored by grants NNX09AR52G, NNG10HP06C – ARRA, and NNX11AD33G. The altimetry acquisition piggybacked in Antarctica on ICECAP and GIMBLE (sponsored by NSF grants PLR-0733025 and PLR-1043761, UK NERC grant NE/D003733/1 to the University of Edinburgh, Australia's ACE-CRC, AAD project 3103 and 4077), and in Greenland on IPEV project DATACO, and GrOGG (sponsored by UK NERC grant NE/H020667 to the Scott Polar Research Institute). The Danish Technical University provided the Embedded GPS/INS (EGI) Intertial Navigation System (INS) used in the 2010-2011 field season. See Support: Funding: and Institutions: fields in granules for specific information for each file.

2. Detailed Data Description

Format

The data files are in space-delimited ASCII text format. Each data file is paired with an associated XML file. The XML files contain location, platform, and instrument metadata.

File and Directory Structure

Data are available on the FTP site in the ftp://n5eil01u.ecs.nsidc.org/SAN2/ICEBRIDGE/ILUTP2.001/ directory. Within this directory, the folders are organized by date, for example /2008.12.29/ to /2013.01.22/. Folders contain ASCII (.txt) and XML (.xml) files.

File Naming Convention

The data files are named according to the following convention and as described in Table 1:

File name examples:
ILUTP2_2013022_ICP5_JKB2h_F26T04a_srfelv.txt
ILUTP2_2013022_ICP5_JKB2h_F26T04a_srfelv.txt.xml

ILUTP2_YYYYDOY_AAAN_JKBna_Xnna_srfelv.xxx

Where:

Table 1. File Naming Convention
Variable Description
ILUTP2 Short name for IceBridge Riegl Laser Altimeter L2 Geolocated Surface Elevation Triplets
YYYY Four-digit year of survey
DOY Day of year of survey
AAAN Geographic area
JKBna Host platform
Xnna Geographic track line
srfelv Surface range
xxx Indicates ASCII text file (.txt), or or XML file (.xml)

File Size

The data files range from approximately 2 KB to 2.5 MB.

Volume

The entire data set is approximately 321 MB.

Spatial Coverage

Spatial coverage for the Riegl Laser Altimeter data includes Greenland and Antarctica. This represents the coverage noted below.

Greenland:
Southernmost Latitude 59° N
Northernmost Latitude: 83° N
Westernmost Longitude: 74° W
Easternmost Longitude: 12° W

Antarctica:
Southernmost Latitude: 90° S
Northernmost Latitude: 53° S
Westernmost Longitude: 180° W
Easternmost Longitude: 180° E

Figure one shows spatial coverages for Antarctica by campaign year.

Figure 1. Antarctic Temporal and Spatial Coverage

Spatial Resolution

The effective footprint of the laser data is 25 m along track by 1 meter across track.

Projection and Grid Description

Referenced to WGS-84 Ellipsoid, ITRF-2008.

Temporal Coverage

These data were collected as part of ICECAP, NSF, NERC, and Operation IceBridge funded campaigns from 29 December 2008 to the present.

Temporal Resolution

IceBridge campaigns are conducted on an annual repeating basis. Arctic and Greenland campaigns are conducted during March, April, and May, and Antarctic campaigns are conducted between October and February.

Parameter or Variable

Parameter Description

The Riegl Laser Altimeter L2 files contain fields as described in Table 2.

Table 2. Parameter Description
Parameter Units
Year UTC
Day of Year UTC
Second of day UTC
Longitude Angle, WGS-84 Degrees
Latitude Angle, WGS-84 Degrees
Laser Derived Surface Range (WGS-84, ITRF2005) Meters

Missing values have been replaced by nan.

Horizontal positions represent aircraft location at the time of the observation.

Sample Data Record

Shown below are the first ten data records from the data file: ILUTP2_2013013_ICP5_JKB2h_F20T01a_srfelv.txt

3. Data Access and Tools

Data Access

Data are available via FTP.

Software and Tools

No special tools are required for the ASCII text files.

4. Data Acquisition and Processing

Data Acquisition Methods

The data were collected using a Riegl LD90-3800-HiP-LR combined with a range of GPS receivers and Inertial Measurement Unit (IMU) systems, mounted in a DC-3T (Basler BT-67) survey aircraft. Typical survey heights were 800 meters above the ice surface. Typical survey speeds were 90 meters/second. Pointing biases were recovered from aircraft crossovers.

Positioning and orientation for Antarctica 2009 came from loosely coupled joint Precise Point Position (PPP)/inertial solutions using an OEM-4 GPS receiver and a Honeywell HG1700/AG58 IMU. In 2010-11, positioning came from PPP solutions on a Javad GPS receiver, while orientation real time output from a Honeywell H-764 EGI (s/n #6038) provided by Danish Technical University as part of the IceGrav project. Positioning and orientation for Antarctica 2011 and 2012, and the 2011 Greenland field season came from loosely coupled joint PPP/inertial solutions using an OEM-4 GPS receiver and an iMAR FSAS IMU. Some flights during Greenland 2011 had corrupted IMU data, and thus are unavailable. See Young et al. 2014 for details of data acquisition and calibration, and see the granule metadata for specific combination used.

Trajectory and Attitude Data

Except for the 2010 field season, trajectory information was derived using Waypoint Inertial Explorer loosely coupled PPP/IMU processing. See product IceBridge GPS/IMU L1B Primary Position and Attitude Solution (IPUTG1B) and Young et al. 2014 for details.

Processing Steps

Cloud filtering was performed by passing only continuous sections 20 meters long, with jumps between samples of 2 meters rejected. Ranges of less than 150 meters were also rejected. Default ranges where a surface was not detected by the laser ranger were -1 meters. Range vectors were transformed into elevations through the vector algebra reviewed in Koks, 2008.

Version History

On 05 July, 2013, the V01 2009, 2010, and 2011 Antarctica data were replaced by V01.1. V01.1 data files were revised in the Seconds field and the Laser Derived Surface field.

Error Sources

The primary sources of errors are:

The net error is approximately 12 cm.

Sensor or Instrument Description

The instrument has been used and validated in previous field campaigns (Young et al. 2014). The instrument is a Riegl LD90-3800-HiP-LR distance meter, with a 3.5 mW diode laser operating at 905 nm. The Laser Altimeter System (LAS) acquires measurements at 2000 Hz, with a range resolution of 2 mm and ground spot width of approximately 1 m. For each block of 575 pulses, the greatest range is recorded, along with the standard deviation and maximum amplitude of the detected pulse echoes. Samples were time stamped using a 100 kHz counter timer, along with a precise timing signal from GPS clock. Typical point separation on the ground was 21–23 m, as expected for a target ground speed of 90 m-s-1. The maximum range of the system is 1500 m over ice.

5. References and Related Publications

Koks, D. 2006. Using Rotations to Build Aerospace Coordinate Systems, Australian Government Department of Defence, Defence Science and Technology Organization, DSTO-TN-0640.

Young, D. A., S. D. Kempf, D. D. Blankenship, J. W. Holt, and D. L. Morse. 2008. New airborne laser altimetry over the Thwaites Glacier Catchment, West Antarctica, Geochemistry, Geophysics, Geosystems 9(6):Q06006, doi:10.1029/2007GC001935.

Young, D. A., L. E. Lindzey, D. D. Blankenship, J. S. Greenbaum, A. G. de Gorordo, S. D. Kempf, J. L. Roberts, R. C. Warner, T. van Ommen, M. J. Siegert, and E. Le Meur. 2014. Land-ice elevation changes from photon counting swath altimetry: First applications over the Antarctic ice sheet, Journal Of Glaciology 61(225):17-28, doi:10.3189/2015JoG14J048.

Related Data Collections

Related Web Sites

6. Document Information

Acronyms and Abbreviations

The acronyms used in this document are listed in Table 3.

Table 3. Acronyms and Abbreviations
Acronym Description
AAD Australian Antarctic Division
ACE-CRC Antarctic Climate and Ecosystems Collaborative Research Center
ASCII American Standard Code for Information Interchange
CIRES Cooperative Institute for Research in Environmental Science
EGI Embedded GPS/INS
FTP File Transfer Protocol
GIMBLE Geophysical Investigations of Marie Byrd Land Lithospheric Evolution
GPS Global Positioning System
GrOGG Greenland Outlet Glacier Geophysics
ICECAP Investigating the Cryospheric Evolution of the Central Antarctic Plate
IMU Inertial Measurement Unit
INS Inertial Navigation System
IPEV Institut Paul Emile Victor (French Polar Institute)
ITRF International Terrestrial Reference Frame
JPEG Joint Photographic Experts Group
L1B Processing Level-1B
LAS Laser Altimeter System
NASA National Aeronautics and Space Administration
NERC Natural Environment Research Council
NSF National Science Foundation
NSIDC National Snow and Ice Data Center
PPP Precise Point Position
URL Uniform Resource Locator
UTC Universal Time Code
VHF Very High Frequency
WGS-84 World Geodetic System 1984

Document Creation Date

24 March 2015

Document Revision Date

.....

Document URL

http://nsidc.org/data/docs/daac/icebridge/ilutp2/index.html