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.
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://nsidc.org/data/ilutp2.html.
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://nsidc.org/data/ilutp2.html.
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://nsidc.org/data/ilutp2.html.
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://nsidc.org/data/ilutp2.html.
Riegl Laser Altimeter
Antarctica and Greenland
25 m along track by 1 meter across track
29 December 2008 to the present
ASCII text (.txt) and XML (.xml)
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
Antarctic Climate and Ecosystems CRC
University of Tasmania
Martin J. Siegert
Faculty of Natural Sciences
The Grantham Institute for Climate Change
National Space Institute
Danish Technical University
Steven J. Palmer
Department of Geography
University of Exeter
Julian A. Dowdeswell
Scott Polar Research Institute
University of Cambridge
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
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.
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.
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.
The data files are named according to the following convention and as described in Table 1:
File name examples:
|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|
|Xnna||Geographic track line|
|xxx||Indicates ASCII text file (.txt), or or XML file (.xml)|
The data files range from approximately 2 KB to 2.5 MB.
The entire data set is approximately 321 MB.
Spatial coverage for the Riegl Laser Altimeter data includes Greenland and Antarctica. This represents the coverage noted below.
Southernmost Latitude 59° N
Northernmost Latitude: 83° N
Westernmost Longitude: 74° W
Easternmost Longitude: 12° W
Southernmost Latitude: 90° S
Northernmost Latitude: 53° S
Westernmost Longitude: 180° W
Easternmost Longitude: 180° E
Figure 1. Antarctic Temporal and Spatial Coverage
The effective footprint of the laser data is 25 m along track by 1 meter across track.
Referenced to WGS-84 Ellipsoid, ITRF-2008.
These data were collected as part of ICECAP, NSF, NERC, and Operation IceBridge funded campaigns from 29 December 2008 to the present.
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.
The Riegl Laser Altimeter L2 files contain fields as described in Table 2.
|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.
Shown below are the first ten data records from the data file: ILUTP2_2013013_ICP5_JKB2h_F20T01a_srfelv.txt
Data are available via FTP.
No special tools are required for the ASCII text files.
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.
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.
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.
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.
The primary sources of errors are:
The net error is approximately 12 cm.
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.
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.
The acronyms used in this document are listed in Table 3.
|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|
|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|
|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|
24 March 2015