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
The following example shows how to cite the use of this data set in a publication. 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
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