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Data Set ID: 
NSIDC-0639

Ice Sheet Model Output, West Antarctic Ice Sheet Deglaciation, Version 1

Ice-sheet model output of Antarctic Ice Sheet simulations spanning 30,000 years BP to 5000+ years in the future.

Geographic Coverage

Parameter(s):
  • Glaciers/Ice Sheets > Glacier Elevation/Ice Sheet Elevation
  • Snow/Ice > Snow/Ice Temperature > Ice Temperature
  • Snow/Ice > Ice Depth/Thickness > Ice Thickness
  • Snow/Ice > Ice Velocity
  • Topography > Terrain Elevation > Surface Elevation
Spatial Coverage:
  • N: -82, S: -82, E: -85, W: -85

Spatial Resolution:
  • 20 km
Temporal Coverage:
  • 1 January 2015 to 2 January 2015
Temporal Resolution: Varies
Data Format(s):
  • NetCDF
  • ASCII Text
Platform(s) Laboratory
Sensor(s): Comp
Version: V1
Data Contributor(s): David Pollard
Please contact the data provider for the correct Data Citation for this data set.

Literature Citation

As a condition of using these data, we request that you acknowledge the author(s) of this data set by referencing the following peer-reviewed publication.

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Detailed Data Description

This data set contains ice-sheet model output of Antarctic ice sheet simulations spanning 30,000 years BP to 5000+ years into the future, in large ensembles of up to 625 individual runs with varying parameter values. The files can be used to generate statistics of variability in the model output.

Format

Data are in NetCDF (.nc) abd ASCII text formats. The ASCII files are tab-delimited.

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File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0639_pollard directory. Within this directory there are six folders, and within each folder, there are between 25 to 625 files for a total of 2541 files. See Figure 1 for the folder names and Figure 2 for a sample of the file listing (this image is only a partial representation of the files in the directory).

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Figure 1. Folder Directory
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Figure 2. Sample of the File List
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File Naming Convention

The file names indicate the parameter value of each run. Files named fort.92_*.nc are netCDF files, and those named fort.22_* are ASCII tab-delimited text.

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File Size

The NetCDF files range from 5.2 to 16.8 MB, and the ASCII files range from .16 to 5.4 MB.

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Volume

The total data volume is 6.5 GB.

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Spatial Coverage

The Domain Center on the grid projection is at 82.0° S; 85.0° W.

Spatial Resolution

For the model grid, the spatial resolution of the data is every 20 km.

Projection and Grid Description

Data are plotted on a polar stereographic 20 km grid, 171x171 points, spanning West Antarctica. Domain center is 82.0° S, 85.0° W.

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Temporal Coverage

Data were collected from 01 January 2015 to 02 January 2015. The data span from 30,000 BP to 5000+ years into the future.

Temporal Resolution

The NetCDF files have a 1000-year temporal resolution, and the ASCII tabular files have a resolution of every two years.

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Parameter or Variable

The parameters for this data set are:
Ice Sheet Elevation (m)
Ice Temperature (°C)
Ice Thickness (m)
Ice Velocity (m/y)
Surface Elevation (m)

Sample Data Record

NetCDF files have selected two-dimensional model fields at 1000 year intervals, on a polar stereographic 20 km grid. See Table 1 for an explanation of the main model data fields and Figure 3 for a sample of the data.

Table 1. Main Model Data Fields
Field Definition
h ice thickness (m)
hs surface elevation (m)
hb bed elevation (m)
maskwater land/ocean mask (0/1)
tb basal temperature (°C)
ts surface temperatre (°C)
ua mean ice x-velocity (m/yr)
va meain ice y-velocity (m/yr)
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Figure 3. Sample Model Data

Tabular output (ASCII files) contain columns of domain-average or integrated model quantities at regular two year intervals for one run. Quantites are labelled in a header row. Refer to Table 2 for the main ice sheet data fields and Figure 4 for a sample of the tabular ouput data (the image is only a partial representation of the columns in the file).

Table 2. Tabular Data Fields
Field Definition
toti total ice volume (km3)
tota total ice area (km2)
esl equivalent global sea-level rise (m)
ASCII data
Figure 4. Sample of Tabular Output Datta List
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Software and Tools

In order to view the data, download the free software Panoply netCDF, HDF and GRIB Data Viewer from NASA

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Data Acquisition and Processing

Data Sources

The following sources provided the main input data for the Antarctic Ice Sheet model used for this data set. See Table 3 for the variables from each data source.

Table 3. Data Sources
Reference Variable
Fretwell, P., et al. 2013. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. The Cryosphere 7(1): 375-393. doi: 10.5194/tc-7-375-2013. Ice Thickness and Bedrock Elevation
Bindschadler, Robert A., et al. 2013. Ice-sheet model sensitivities to environmental forcing and their use in projecting future sea level (the SeaRISE project). Journal of Glaciology 59(214): 195-224. doi: 10.3189/2013JoG12J125. Climatological Atmospheric Precipitation and Temperature
Liu, Z., et al. 2009. Transient Simulation of Last Deglaciation with a New Mechanism for Bølling-Allerød Warming. Science Magazine 325(5938): 310-314. doi: 10.1126/science.1171041. Ocean Temperatures from the Global Climate Model (GCM) simulation of last 22,000 years
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Derivation Techniques and Algorithms

Processing Steps

All data are model ouptuts, generated on computers running the numerical ice sheet model. For a description of the ice sheet model formulation, see Pollard and DeConto, 2012.

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References and Related Publications

Contacts and Acknowledgments

David Pollard
Pennsylvania State University
Earth and Environmental Systems Institute
2217 Earth-Engineering Science Building
University Park, PA 16802

Acknowledgments: 

This research was supported by NSF Division of Polar Programs (PLR) Grant Number 1043018.

Document Information

Document Creation Date

10 November 2015

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