Singular Value Decomposition Analysis of Ice Sheet Model Output Fields

Summary

This data set provides the results of predictive modeling experiments on the Amundsen Sea Embayment region of Antarctica. The models examine how interactions between basal processes and ice sheet dynamics can result in abrupt reconfigurations of ice-sheets, and how those reconfigurations impact other Earth systems. The models were developed by a collaborative effort called the Community Ice Sheet Model (CISM).

The data set contains a MATLAB (.mat) native format file with time evolution of basal temperature fields from a generic ice sheet model with uniform and non-uniform heat flux, a MATLAB script for performing singular value decomposition and analysis of the model fields, and a summary of experimental results in Portable Document Format (.pdf). Data 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.

The following example shows how to cite the use of this data set in a publication. List the principal investigators, year of data set release, data set title and version number, publisher: NSIDC, and digital media.

Hulbe, C. 2009. Singular Value Decomposition Analysis of Ice Sheet Model Output Fields. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5K64G1S.

Overview Table

Category	Description
Data format	MATLAB (.mat), Portable Document Format (.pdf)
Spatial coverage and resolution	Southernmost Latitude: 90°S Northernmost Latitude: 60°S Westernmost Longitude: 180°W Easternmost Longitude: 180°E
Temporal coverage and resolution	The data set is a predictive model describing conditions for 200,000 years.
File naming convention	eismint2data.mat SVDreport.pdf svdanalysis.m
File size	2.4 MB
Parameter(s)	Model-derived basal temperature evolution
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(s)

Christina Hulbe
Associate Professor
Portland State University
Department of Geology
P.O. Box 751
Portland, OR 97207

Dacian N. Daescu
Assistant Professor
Portland State University
Department of Mathematics
P.O. Box 751
Portland, OR 97207, USA

Technical Contact

Acknowledgements

This research was funded by NSF OPP grant 0632168.

2. Detailed Data Description

Format

Data are available in MATLAB file format.

File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/hulbe_nsidc_0396/ directory. Within this directory, there are four files, described in Table 1:

 

Table 1. List of Files in the /hulbe_nsidc_0396/ Directory

Filename	Description
eismint2data.mat	MATLAB native file containing model data and output
svdanalysis.m	MATLAB script performing singular value decomposition and analysis of model fields.
SVDreport.pdf	PDF file describing the results of the model experiment
readme.txt	Text file describing the data

 

File Size

The eismint2data.mat file is 2.4 MB. Other files range in size from 4 KB to 320 KB.

Spatial Coverage

The data set focuses on the Amundsen Sea Embayment region of Antarctica.

Southernmost Latitude: 90°S
Northernmost Latitude: 60°S
Westernmost Longitude: 180°W
Easternmost Longitude: 180°E

Spatial Resolution

Resolution is 25 kilometers.

Grid Description

The arrays contain 201 1,000 year time steps in the first dimension, and 61² grid points in the second dimension.

Temporal Coverage

The data set is a predictive model spanning 200,000 years.

Temporal Resolution

Time steps are 1,000 years.

Parameter or Variable

Parameter Description

Model derived basal temperature evolution

Sample Image

Model Output Image: Structure of the Leading Left SV, Non-uniform Case

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

The entire data set is less than 3 MB.

4. Data Acquisition and Processing

Data Source

Source data used for model preparation include present day data on mean annual surface temperature, ice thickness, accumulation/ablation rate, ice surface elevation, bed topography, basal heat flux, thickness mask, surface velocity, melt(Ross ice streams), and surface balance velocity. Detailed information on the data used is available from the Community Ice Sheet Model: Data Web page.

Derivation Techniques and Algorithms

The eismint2data.mat file contains two outputs:

uniformData 201x3721
variableData 201x3721

These are output of basal temperature (C). The grid is 61x61, spaced 25 km. The arrays contain 201 1,000 year time steps in the first dimension, and 61^2 grid points in the second dimension. For the uniform case, the experiment was EISMINT II H. The variable case looks at what happens when one of the boundary conditions (basal heat flux) is non-uniform.

For more information on the methodology, visit the Community Ice Sheet Model Web page

5. References and Related Publications

Daescu, D. N. and I. M. Navon. 2008. A Dual-Weighted Approach to Order Reduction in 4DVAR Data Assimilation. Monthly Weather Review, 136, 1026-1041.

Table 2 lists related documents that are available online.

Table 2. Related Documents

Document	Description	URL
Antarctic Glaciological Data Center	Project home page	http://nsidc.org/agdc/
Community Ice Sheet Model	Model information	http://websrv.cs.umt.edu/isis/index.php/Main_Page

6. Document Information

Acronyms

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

Table 3. Acronyms and Abbreviations

Acronym	Description
CISM	Community Ice Sheet Model
FTP	File Transfer Protocol
NSIDC	National Snow and Ice Data Center
SVM	Singular Value Decomposition
URL	Uniform Resource Locator

Document Creation Date

15 May 2009

Document URL

http://nsidc.org/data/docs/agdc/nsidc0396_hulbe/index.html