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Data Set ID:
NSIDC-0494

Grounding Line Strain Grid Surveys, Kamb Ice Stream, Antarctica, Version 1

This data set provides the results from a strain grid survey deployed across the Kamb Ice Stream grounding line on the West Antarctic Ice Sheet. The grid was deployed in 2006 and resurveyed in 2007 using a Global Positioning System (GPS). Parameters measured include latitude, longitude, and height of each survey mark in the strain grid, as well as northing, easting, elevations, and displacement of each point during the year between surveys.

Data are available via FTP in Microsoft Excel (.xls) format.

Geographic Coverage

Parameter(s):
  • Glaciers/Ice Sheets > Glacier Motion/Ice Sheet Motion
  • Snow/Ice > Ice Motion
  • Glaciers/Ice Sheets > Ice Sheets
Spatial Coverage:
  • N: -82.78, S: -82.86, E: 155.51, W: 154.71

Spatial Resolution:
  • 1 km x 1 km
Temporal Coverage:
  • 27 November 2006 to 30 November 2007
Temporal Resolution: 1 year
Data Format(s):
  • Microsoft Excel
Platform(s) FIELD SURVEYS, GPS
Sensor(s): GPS, GPS RECEIVERS
Version: V1
Data Contributor(s): Christina Hulbe
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.

Hulbe, C. 2011. Grounding Line Strain Grid Surveys, Kamb Ice Stream, Antarctica, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5Z899C6. [Date Accessed].

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Detailed Data Description

Format

Data are in Microsoft Excel (.xls) 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/nsidc0494_hulbe_V01/ directory. This data set contains one file, KISgroundingline_GPS.xls contains the measurements and displacement information for each site in the strain grid survey. The directory also contains a readme file in text format, 00README.txt.

Table 1 describes the information and parameters in individual worksheets within the Excel file.

Table 1. Description of Workheets in the KISgroundingline_GPS.xls File
Worksheet name Data Description
2007 Lat Lon
2006 Lat Lon
These two worksheets contain location information for each survey point in 2006 and 2007, as well as for the base stations where fixed GPS receivers operated throughout each survey. They also include positioning errors.

Parameters:
Latitude
Longitude
Height
2007 ENZ
2006 ENZ
These two worksheets contain the GPS latititude and longitude for each site in 2006 and 2007, converted into easting and northing.

Parameters:
Northing
Easting
Elevation 
Displacements This worksheet contains the computed 2006 to 2007 displacements of the survey marks in the grid.

Parameters:
Station name 
Northing 2006 
Easting 2006
Elevation 2006 
Change in northing (dN)
Change in easting (dE)
Change in elevation (dZ)
Direction of displacement vector (dir)
Magnitude of displacement vector (mag)
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File Size

The file is 131 KB.

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Volume

The data file is 131 KB.

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Spatial Coverage

1 km

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Temporal Coverage

The data consists of two annual surveys of a strain grid. The strain grid was deployed in November 2006 and resurveyed in November 2007.

Temporal Resolution

One year

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Parameter or Variable

This data set contains the locations for each point in the strain grid survey, measured in both 2006 and 2007. It also contains the computed displacements between 2006 and 2007, for each point.

Parameter Description

Table 2. Parameter Description for the KISgroundingline_GPS.xls File
Parameter Description
Point Station name. The stations were deployed in 2006 and resurveyed in 2007, but the names remained the same.
Latitude GPS-measured latitude in decimal degrees
Longitude GPS-measured longitude in decimal degrees
Northing Cartesian coordinates converted from latitude measurement
Easting Cartesian coordinates converted from longitude measurement
Elevation Elevation was calculated from the height measurement using the base station measurements.
dN Change in northing
dE Change in easting
dZ Change in elevation
dir Direction of displacement vector
mag Magnitude of displacement vector

Sample Data Record

Point Northing Easting Elevation dN dE dZ dir mag
KA1 1282329.670 1662067.546 108.544 -0.077 0.061 -0.051 -51.61346042 0.098234413
KA2 1281527.884 1661464.518 108.985 -0.041 0.056 0.087 -36.20945675 0.069404611
KA3 1280658.332 1660882.114 110.748 -0.039 0.04 -0.018 -44.27477558 0.055865911
KA4 1279841.147 1660302.648 112.139 -0.037 0.014 0.008 -69.27444119 0.039560081
KA5 1278979.274 1659704.973 112.172 -0.055 0.015 -0.106 -74.74488138 0.057008771

This sample data record shows the first 5 records in the displacements worksheet.

Sample Image

map showing straing grid sites
Figure 1. This map shows the locations of the survey marks in the strain grid (green circles). Contour lines show surface elevation (in meters) from the GPS surveys. The black lines are the traces of strand cracks in the region where the ice goes from grounded (the KA side) to floating (the KK side).
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Software and Tools

Software and Tools

Data are accessible using Microsoft Excel software.

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Data Acquisition and Processing

Theory of Measurements

A strain grid is a set of survey marks (metal conduits planted vertically in the snow) that are set out in a grid with relatively uniform spacing, surveyed, and then resurveyed. Changes in the vector lengths among the poles are used to compute strain rates at centroids of quadrilaterals (or triangles) formed using adjacent survey marks.

For every survey, the researchers established two base stations that recoreded a continuous GPS signal while other GPS receivers roved around the grid. The rovers stopped at marks in the grid and occupied them for 15 to 20 minutes. The resulting network of vectors (between the two base stations and each of the rover stops) is used to calculate the relative positions of all the marks in the grid. Absolute positions are determined using data from the base stations.

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References and Related Publications

Contacts and Acknowledgments

Dr. Christina Hulbe 
Portland State University 
Department of Geology 
P. O. Box 751 
Portland, Oregon, 97207
USA

Acknowledgments: 

This research was supported by NSF Office of Polar Programs grant number 0538015.

Document Information

DOCUMENT CREATION DATE

June 21, 2011

No technical references available for this data set.
No FAQs or How Tos available for this data set.

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