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UMISM Amundsen Sea Sector Data Set

Summary

This data set includes a nested model, that starts at low resolution for the whole Antarctic Ice Sheet, and then embeds higher resolution data at limited domains. There are at least three levels of nesting: whole, regional, and specific ice streams. Investigators focused on the Thwaites Glacier and the Pine Island Glacier. The model was produced using data from (Holt et al. 2006) and (Vaughan et al. 2006). Data are in Network Common Data Form (NetCDF) format and are available via FTP.

Citing These Data

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

Fastook, James. 2007. UMISM Amundsen Sea Sector data set. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5J9649Q.

Overview Table

Category Description
Data format NetCDF (Network Common Data Form)
Spatial coverage and resolution Antarctic Continent at 40 kilometers
Amundsen Sea Embayment at 10 kilometer
Pine Island Glacier at 5 kilometer
Thwaites Glacier at 5 kilometer
Temporal coverage and resolution 2004/2005 Austral Summers (December 21 through March 21)
Tools for accessing data Ncview
File naming convention netcdf-###.nc
File size Approximately 9.27 MB to 223 MB
Parameters Bed elevation, ice thickness, net annual accumulation or ablation, ice hardness, ice temperature, ice melt rate, and column-average ice velocity
Procedures for obtaining data Data are available via FTP.

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

1. Contacts and Acknowledgments

Investigator

James L. Fastook
Department of Computer Sciences
University of Maine
Neville Hall
Orono, ME 04469-5790
USA

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

The National Science Foundation (NSF) supported the development of the model producing these data over many years through several awards. The investigator used flight-line data and surface elevation data from the Airborne Geophysical Survey of the Amundsen Sea Embayment (AGASEA) and the British Antarctic Survey (BAS), respectively.

2. Detailed Data Description

Format

Data are in NetCDF, which uses rectangular arrays, rows and columns like positions on a checkerboard. For more information on the NetCDF file format, please see the NetCDF Resources at NSIDC Web site. The following table describes the arrays included in each file.

Array Name Description
htice Ice surface elevation relative to present sea level
bedrock Bed elevation, also relative to present sea level, which varies due to isostatic response to changing load
thick Ice thickness, conceptually the differnce between htice and bedrock
adot Net annual accumulation, if value is positive, or ablation, if value is negative, in meters per year (m/yr) ice equivalent
flowa "Effective" ice hardness (a function of the temperature structure within the ice column)
tbed Temperature at the base of the ice column
bmelt Rate at which ice melts from the base of the ice column, where the bed is at pressure melting point; the source of water for the wthick measurement
wthick Amount of water at the bed, expressed as a "thickness" velocity; a column-average ice velocity (m/yr)

File Naming Convention

Files are named according to the convention netcdf-###.nc

File Name Approximate
File Size
Description
netcdf-a1.nc 44.1 MB Continent- Glacier cycle at 40 kBP to present
netcdf-a2.nc 16.7 MB Continent- Glacier cycle at present to 2000 years into the future
netcdf-a23.nc 223.0 MB Continent - short run over 200-300 year period
netcdf-e1.nc 24.4 MB Amundsen Embayment - Glacier cycle at 40 kBP to present
netcdf-e2.nc 9.27 MB Amundsen Embayment - Glacier cycle at present to 2000 years into the future
netcdf-e22.nc 30.9 MB Amundsen Embayment - short run over 200-300 year period
netcdf-e23.nc 123.0 MB Amundsen Embayment - short run over 200-300 year period
netcdf-e24.nc 123.0 MB Amundsen Embayment - short run over 200-300 year period
netcdf-f1.nc 29.6 MB Twaites Glacier - Glacier cycle at 40 kBP to present
netcdf-f2.nc 37.4 MB Twaites Glacier - Glacier cycle at present to 2000 years into the future
netcdf-f22.nc 78.7 MB Twaites Glacier - short run over 200-300 year period
netcdf-f23.nc 41.2 MB Twaites Glacier - short run over 200-300 year period
netcdf-g1.nc 17.3 MB Pine Island Glacier - Glacier cycle at 40 kBP to present
netcdf-g2.nc 21.9 MB Pine Island Glacier - Glacier cycle at present to 2000 years into the future
netcdf-g22.nc 46.1 MB Pine Island Glacier - short run over 200-300 year period

Spatial Coverage and resolution

Antarctic Continent at 40 kilometers
Amundsen Sea Embayment at 10 kilometers
Pine Island Glacier at 5 kilometers
Thwaites Glacier at 5 kilometers

Temporal Coverage

2004/2005 Austral Summers

Parameter or Variable

Glacier topography
Ice Sheet topography
Bed elevation
Ice Thickness
Net annual accumulation
Effective ice hardness
Temperature at base of ice column

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The volume of the entire data set is approximately 517 MB compressed.

Software and Tools

For a list of tools for reading/viewing netCDF files, please see the NetCDF Resources at NSIDC: Software and Tools Web page.

Related Data Collections

4. Data Acquisition and Processing

Sensor or Instrument Description

Original ice thickness data collected by RADAR sounders from survey aircraft. Surface elevation collected using RADAR and LASER altimeters.

Data Acquisition Methods

Original data collected by survey aircraft as part of Airborne Geophysical Survey of the Amundsen Sea Embayment (AGASEA). See: Subglacial Topography: Airborne Geophysical Survey of the Amundsen Sea Embayment, Antarctica

Derivation Techniques and Algorithms

Model data is derived from University of Maine Ice Sheet model.

Processing Steps

Model was used in the embedded mode to do high resolution analysis of the velocity distribution.

5. References and Related Publications

Courville, Z. R., M. R. Albert, M. A. Fahnestock, L. M. Cathles, IV, and C. A. Shuman. 2007. Impacts of an accumulation hiatus on the physical properties of firn at a low-accumulation polar site. Journal of Geophysical Research 112, F02030, doi: 10.1029/2005JF000429

Holt, J. W., D. D. Blankenship, D. L. Morse, D. A. Young, M. E. Peters, S. D. Kempf, T. G. Richter, D. G. Vaughan, H. F. J. Corr. 2006. New boundary conditions for the West Antarctic Ice Sheet; subglacial topography of the Thwaites and Smith Glacier catchments. Geophysical Research Letters L09502, doi: 10.1029/2005GL025561

Vaughan, D. G., H. F. J. Corr, F. Ferraccioli, N. Frearson, A. O'Hare, D. Mach, J. W. Holt, D. D. Blankenship, D. L. Morse, D. A. Young. 2006. New boundary conditions for the West Antarctic Ice Sheet; subglacial topography beneath Pine Island Glacier. Geophysical Research Letter doi: 10.1029/2005GL025588.

The following related documents are available on NSIDC's Web site.

Document
Description
URL
Subglacial Topography: Airborne Geophysical Survey of the Amundsen Sea Embayment, Antarctica This data set includes 5 km gridded data from the Airborne Geophysical Survey of the Amundsen Sea Embayment, Antarctica (AGASEA) conducted during the 2004-2005 austral summer covering the entire catchments of both the Thwaites Glacier and the Pine Islands Glacier. http://nsidc.org/data/nsidc-0292.html
NetCDF Resources at NSIDC Gives a brief summary of netCDF files, a list of tools for accessing these files, and a list of data sets in netCDF format at NSIDC. http://nsidc.org/data/netcdf/

6. Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AGASEA Airborne Geophysical Survey of the Amundsen Sea Embayment
AGDC Antarctic Glaciological Data Center
BAS British Antarctic Survey
FTP File Transfer Protocol
LGM Last Glacial Maximum
NetCDF Network Common Data Form
NSIDC National Snow and Ice Data Center
SAR Synthetic Aperature Radar
UMISM University of Maine Ice Sheet Model
URL Uniform Resource Locator

Document Creation Date

October 2007

Document URL

http://nsidc.org/data/docs/agdc/nsidc0312_fastook/index.html