Polarimetric Radar Data from the Ross and Amundsen Sea Ice Flow Divide, West Antarctica

Summary

This dataset contains ground-based, co-polarized radar data collected using pulse-modulated 60 MHz and 179 MHz radar at 19 sites around a deep ice coring site near the Ross and Amundsen flow divide of West Antarctic Ice Sheet (WAIS Divide). At each site, the radar data were collected at 12 orientations of the radar polarization plane for three radar pulse widths: 250 nsec, 500 nsec, and 1000 nsec. Useful signals were received from depths roughly between 200 m and 2000 m. Ice flow velocities and strain configurations were measured at most of these radar survey sites, and these ice motion data are also provided at NSIDC (GPS-Measured Ice Velocities and Strain Data from the Ross and Amundsen Sea Ice Flow Divide, West Antarctica).

Data are available via FTP in MATLAB (.mat) format.

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, publisher: NSIDC, and digital media.

Matsuoka, K., D. Power, S. Fujita and C. Raymond. 2011. Polarimetric Radar Data from the Ross and Amundsen Sea Ice Flow Divide, West Antarctica. Boulder, Colorado, USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5TH8JNG.

Overview Table

Category	Description
Data format	MATLAB
Spatial coverage and resolution	Southernmost Latitude: 79.6401°S Northernmost Latitude: 78.7489°S Westernmost Longitude: 115.457°W Easternmost Longitude: 109.128°W
Temporal coverage and resolution	Radar data were collected between November 2005 and January 2007
File naming convention	WAISDividePolarimetry.mat
File size	12.7 MB
Parameters	Radar signals collected at 12 orientations of the radar polarization plane for three radar pulse widths: 250 nsec, 500 nsec, and 1000 nsec.
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

Investigators

Dr. Kenichi Matsuoka
Department of Earth and Space Sciences
Box 351310
University of Washington
Seattle, WA 98195
USA

Dr. Donovan Power
Department of Earth and Space Sciences
Box 351310
University of Washington
Seattle, WA 98195
USA

Dr. Shuji Fujita
National Institute of Polar Research
Tokyo, Japan

Dr. Charles Raymond
Department of Earth and Space Sciences
Box 351310
University of Washington
Seattle, WA 98195
USA

Technical Contact

Acknowledgements

This research was supported by the National Science Foundation (NSF) Office of Polar Programs (OPP) grant number 0440847.

2. Detailed Data Description

Format

Data are in MATLAB (.mat) format.

File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/nsidc0496_matsuoka_V01/ directory. This directory contains one data file in MATLAB (.mat) format.

Data Structure

In the single MATLAB file, there are 19 structures, each of which corresponds to the data collected at a measurement site. Structures include eight variables, described under Parameter Description.

File Naming Convention

The data set consists of one MATLAB file, named WAISDividePolarimetry.mat.

File Size

12.7 MB

Spatial Coverage

Polarimetric radar data were obtained on the West-Antarctic Ice Sheet, at 12 orientations with 15° increments.

Southernmost Latitude: 79.6401°S
Northernmost Latitude: 78.7489°S
Westernmost Longitude: 115.457°W
Easternmost Longitude: 109.128°W

Spatial Coverage Map

Figure 1. a. Map of the Antarctic Ice Sheet showing broad location of study area (b)
b. Regional surface topography (contours) and ice thickness (background color) in the WAIS Divide area: Gray rectangle indicates study area (c).Thick contours are drawn at 500 m intervals, and thin contours are drawn at 100 m. Byrd and WAIS Divide ice core sites are shown with white crosses. Surface topography is from Liu et al. 1999, and ice thickness is a composite of a continental BEDMAP model (Lythe et al., 2001) and a regional model by Support Office for Aerogeophysical Research (Morse et al., 2002).
c. Local surface topography (contours) and ice thickness (background color) in the WAIS Divide area, along with site names.
White circles show polarimetric radar measurement sites, and GPS ice-motion measurement sites are shown with blue circles.
Ninety eight GPS markers were installed for mass balance study in the vicinity of the flowline through WAIS Divide core site, shown with blue dots (Conway and Rasmussen, 2009). Airborne along-flow radar profiles used for englacial attenuation analysis are shown with gray curves (Matsuoka et al., 2010).

Site Locations

Table 1 lists the site locations for radar measurements.

Table 1. Site Locations

Name	Latitude	Longitude
S-E30	-79.0717	-110.940
S-E06	-79.2492	-111.226
S-DIV	-79.2992	-111.368
S-W17	-79.4009	-111.948
S-W24	-79.4700	-112.090
NE	-78.7489	-114.290
N-Div	-78.9281	-114.245
NW	-78.8612	-115.251
N-W15	-79.0105	-114.808
N-W30	-79.0648	-115.457
SE2	-79.2378	-109.269
SE1	-79.3268	-109.128
SW1	-79.6401	-109.754
SW2	-79.5579	-110.586
CE3	-78.8134	-112.674
CE2	-79.0013	-112.322
CE1	-79.1186	-111.993
CW1	-79.1947	-113.140

 

Spatial Resolution

Radar measurements were made at 12 orientations with 15° increments from the local fall line, determined with the continental surface elevation model (Liu et al., 1999). Figure 2 below shows a schematic of polarimetric measurments. Angle α is measured from true north to the fall line. The azimuth of the polarization plane of i-th measurement is α + β, where β = 15i (degree).

 

Figure 2. Polarimetric Radar Measurement

Temporal Coverage

Radar data were collected between November 2005 and January 2007.

Parameter or Variable

Radar data are provided in MATLAB format.

Data Description

The MATLAB file consists of 19 structures, each of which corresponds to the data collected at a measurement site. Structures include eight variables. Azimuth shows the orientation (degree) of the first measurement, measured clockwise from true north. TWTtime vector shows two-way travel time (second). The other six matrices show radar data; the matrix name shows radar frequency (after F) and pulse width (before nsec). For example, F179M_1000nsec is a dataset collected with 179 MHz radar and 1000 nsec pulse width. Each radar data matrix is composed of 2500 by 12 cells; 2500-long rows correspond to two-way-travel-time (i.e. depth) series of the returned power (dBm) at a polarization plane. The first 2500-long row is collected at azimuth orientation, and 12th 2500-long row is collected at azimuth +15 x 11 (degree).

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

12.7 MB

Software and Tools

Image can be viewed and processed using MATLAB software.

Related Data Collections

• GPS-Measured Ice Velocities and Strain Data from the Ross and Amundsen Sea Ice Flow Divide, West Antarctica

4. Data Acquisition and Processing

Sensor or Instrument Description

60 MHz and 179 MHz radar systems were installed on a single sled. The timing of the two radar systems was anti-synchronized to prevent interaction (Matsuoka et al., 2002). Two of three-element (60 MHz) and eight-element (179 MHz) yagi antennae were installed each for transmitting and receiving. These antennae were co-polarized with radar polarization planes parallel to the platform travel direction.

Data Acquisition Methods

The sled was aligned along the local fall line (Figure 2), and measurements were made using 250 nsec, 500 nsec, and 1000 nsec pulse widths. After the measurement using three different pulse widths at this orientation, the platform was rotated by 15-degree increments so that measurements were made at 12 orientations spanning 0 to 165 degrees. In each measurement, the radar platform was moved forward or backward over several wavelengths of the radio waves so that speckle noise is mitigated by averaging these radar waveforms.

The data will be described in more detail in Matsuoka, et. al., 2011, a journal article based on these data.

5. References and Related Publications

Conway, H., and L. A. Rasmussen. 2009. Recent Thinning and Migration of the Western Divide, Central West Antarctica. Geophys. Res. Lett., 36, L12502.

Liu, H. X., et al. 1999. Development of an Antarctic Digital Elevation Model by Integrating Cartographic and Remotely Sensed Data: A Geographic Information System-Based Approach, J. Geophys. Res., 104(B10), 23199-23213.

Lythe, M. B., et al. 2001. BEDMAP: A New Ice Thickness and Subglacial Topographic Model of Antarctica. J. Geophys. Res., 106(B6), 11335-11351.

Matsuoka, K., et al. 2010. Estimating Englacial Radar Attenuation Using Depth Profiles of the Returned Power, Central West Antarctica, J. Geophys. Res., 115, F0212.

Matsuoka, K., D. Power, S. Fujita and C. Raymond. 2011. Polarimetric Signatures of Englacial Radar Returned Power near the Ross and Amundsen Sea Ice-Flow Divide (WAIS Divide), West Antarctica.

Morse, D. L., et al. 2002. A Site for Deep Ice Coring in West Antarctica: Results from Aerogeophysical Surveys and Thermo-Kinematic Modeling, Ann. Glaciol., 35, 36-44.

The following related documents are available:

Table 2. Related Documents

Document	Description	URL
Antarctic Glaciological Data Center	Data Center Web site	http://nsidc.org/agdc/

6. Document Information

Acronyms

The following acronyms are used in this document.

Table 3. Acronyms and Abbreviations

Acronym	Description
FTP	File Transfer Protocol
NSIDC	National Snow and Ice Data Center
URL	Uniform Resource Locator
WAIS	West Antarctic Ice Sheet

Document Creation Date

19 August, 2011

Document URL

http://nsidc.org/data/docs/agdc/nsidc0496_matsuoka/index.html