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Data Set ID:
NSIDC-0496

Polarimetric Radar Data from the Ross and Amundsen Sea Ice Flow Divide, West Antarctica, Version 1

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.

Geographic Coverage

Parameter(s):
  • Glaciers/Ice Sheets > Glacier Topography/Ice Sheet Topography
  • Glaciers/Ice Sheets > Ice Sheets
  • Radar > Radar Imagery
  • Snow/Ice
Spatial Coverage:
  • N: -78.7489, S: -79.6401, E: -109.128, W: -115.457

Spatial Resolution: Not Specified
Temporal Coverage:
  • 1 November 2005 to 31 January 2007
Temporal Resolution: Not specified
Data Format(s):
  • MATLAB
Platform(s) FIELD INVESTIGATION
Sensor(s): RADAR
Version: V1
Data Contributor(s): Kenichi Matsuoka, Donovan Power, Shuji Fujita, Charles Raymond
Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Matsuoka, K. 2011. Polarimetric Radar Data from the Ross and Amundsen Sea Ice Flow Divide, West Antarctica, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5TH8JNG. [Date Accessed].

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Detailed Data Description

Format

Data are in MATLAB (.mat) format.

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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.

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File Naming Convention

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

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Volume

12.7 MB

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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

maps showing site locations
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).

schematic showing polarimetric measurement
Figure 2. Polarimetric Radar Measurement

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Temporal Coverage

Radar data were collected between November 2005 and January 2007.

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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).

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Software and Tools

Image can be viewed and processed using MATLAB software.

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Data Acquisition and Processing

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.

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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.

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References and Related Publications

Contacts and Acknowledgments

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 

Acknowledgments: 

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

Document Information

Document Creation Date

19 August, 2011

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