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Data Set ID: 
NSIDC-0642

MEaSUREs Annual Greenland Outlet Glacier Terminus Positions from SAR Mosaics, Version 1

This data set, part of the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) program, provides Greenland outlet glacier terminus positions created from MEaSUREs Synthetic Aperture Radar (SAR) mosaics and Landsat 8 OLI imagery.

See Greenland Ice Mapping Project (GIMP) for related data.

This is the most recent version of these data.

Version Summary: 

Initial release

STANDARD Level of Service

Data: Data integrity and usability verified

Documentation: Key metadata and user guide available

User Support: Assistance with data access and usage; guidance on use of data in tools

See All Level of Service Details

Parameter(s):
  • GLACIERS/ICE SHEETS > GLACIERS > Glacier Extent
Data Format(s):
  • ESRI Shapefile
Spatial Coverage:
N: 83, 
S: 60, 
E: -14, 
W: -75
Platform(s):LANDSAT-8, RADARSAT-1, SENTINEL-1A, SENTINEL-1B
Spatial Resolution:
  • Varies x Varies
Sensor(s):C-SAR, OLI, SAR
Temporal Coverage:
  • 1 February 2017 to 6 April 2017
  • 2 February 2016 to 2 April 2016
  • 21 January 2015 to 31 March 2015
  • 15 January 2013 to 26 March 2013
  • 10 January 2009 to 5 February 2009
  • 22 November 2007 to 30 March 2008
  • 30 December 2006 to 4 February 2007
  • 24 December 2005 to 4 April 2006
  • 30 September 2000 to 23 January 2001
(2017)		Version(s):V1
Temporal Resolution1 yearMetadata XML:View Metadata Record
Data Contributor(s):Ian Joughin, Twila Moon, Jonah Joughin, Taryn Black

Geographic Coverage
Other Access Options

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Once you have logged in, you will be able to click and download files via a Web browser. There are also options for downloading via a command line or client. For more detailed instructions, please see Options Available for Bulk Downloading Data from HTTPS with Earthdata Login.

Earthdata Search: This application allows you to search, visualize, and access data across thousands of Earth science data sets. Additional customization services are available for select data sets, including subsetting, reformatting, and reprojection.

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.

Joughin, I., T. Moon, J. Joughin, and T. Black. 2015, 2017. MEaSUREs Annual Greenland Outlet Glacier Terminus Positions from SAR Mosaics, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/DC0MLBOCL3EL. [Date Accessed].

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.

  • Moon, T. and I. Joughin. 2008. Changes in ice front position on Greenland's outlet glaciers from 1992 to 2007, Journal of Geophysical Research-Earth Surface. 113. Art. #F02022. https://doi.org/10.1029/2007JF000927

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Detailed Data Description

Format

ESRI ArcGIS Shapefile

.shp – main file that stores the feature geometry
.shx – index file that stores the index of the feature geometry
.dbf – dBASE table that stores the attribute information of features
.sbn and .sbx – files that store the spatial index of the features
.prj – file that stores the coordinate system information
.cpg – optional file to specify the code page for identifying the character set to be used

There is also a metadata file (.xml) for each shapefile.

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File and Directory Structure

Data are available on the HTTPS site in https://n5eil01u.ecs.nsidc.org/MEASURES/NSIDC-0642.001/.

Within this directory are the following folders:

Table 1. Top-Level Directory Structure
Folder Name Description
2000.09.30 Winter 2000–2001 glacier terminus position data and glacier IDs
2005.12.24 Winter 2005–2006 glacier terminus position data
2006.12.30 Winter 2006–2007 glacier terminus position data
2007.11.22 Winter 2007–2008 glacier terminus position data
2009.01.04 Winter 2008–2009 glacier terminus position data
2013.01.15 Winter 2012–2013 glacier terminus position data
2015.01.21 Winter 2014–2015 glacier terminus position data
2016.02.02 Winter 2015–2016 glacier terminus position data
2017.02.01 Winter 2016–2017 glacier terminus position data

The 2000.09.30 folder contains 18 files: 9 files for the glacier identifiers and 9 for the terminus position data. All other folders contain 9 files each for the terminus position data.

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File Naming Convention

This section explains the shapefile file naming convention for this data set.

Example File Names:

termini_0809_v01.2.cpg
termini_0809_v01.2.dbf
termini_0809_v01.2.prj
termini_0809_v01.2.sbn
termini_0809_v01.2.sbx
termini_0809_v01.2.shp
termini_0809_v01.2.shx
termini_0809_v01.2.xml

Convention:

termini_XXYY_v01.2.ext
GlacierIDs.ext

Table 2. Naming Convention for Shapefiles
String Description
termini  Glacier terminus position file
GlacierIDs GlacierID denotes a reference file with glacier points and consistent glacier identification number.
XXYY Winter season. For example, 0809 is the winter of 2008–2009.
vxx.x Current version number
EXT File extension. The shapefile (.shp) format includes: .cpg (character set code), .dbf (attributes), .prj (projection information), .sbn and .sbx (spatial index), .shx (feature geometry index), and .xml (metadata).
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File Size

Character set code (.cpg), spatial index (.sbx), and projection (.prj) files average 1 KB.
Spatial index files (.sbn) range from 2 KB to 3 KB.
Feature geometry index files (.shx) average approximately 2 KB.
Database files (.dbf) range from 25 to 68 KB.
Shapefiles (.shp) range from 6 KB to 100 KB.
Metadata files (.xml) average approximately 7 KB.

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Volume

The complete data volume is approximately 1153 KB.

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Spatial Coverage

Southernmost Latitude: 60° N
Northernmost Latitude: 83° N
Westernmost Longitude: 75° W
Easternmost Longitude: 14° W

Spatial Resolution

The nominal uncertainty in digitized position is 50 m, but could be larger in regions where there is poor contrast at the terminus (e.g., melange). Nominal ground resolution for the source SAR mosaics and Landsat ranges between 15 m to 50 m.

Projection and Grid Description

GeoTIFFs are provided in a WGS 84 polar stereographic grid with a standard latitude of 70° N and rotation angle of -45° (sometimes specified as a longitude of 45° W). With this convention, the y-axis extends south from the North Pole along the 45° W meridian (EPSG:3413).

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Temporal Coverage

Data are available for the following winters.

  • 2000–2001
  • 2005–2006
  • 2006–2007
  • 2007–2008
  • 2008–2009
  • 2012–2013
  • 2014-2015
  • 2015-2016
  • 2016-2017

Table 3 lists the exact date ranges for each winter.

Table 3. Date Ranges for Images
Data Year Date Range
2000/01 30 Sept 2000 – 23 Jan 2001
2005/06 24 Dec 2005 – 04 Apr 2006
2006/07 30 Dec 2006 – 04 Feb 2007
2007/08 22 Nov 2007 – 30 Mar 2008
2008/09 10 Jan 2009 – 05 Feb 2009
2012/13 15 Jan 2013 – 26 Mar 2013
2014/15 21 Jan 2015 – 31 Mar 2015
2015/16 02 Feb 2016 – 02 Apr 2016
2016/17 01 Feb 2017 – 06 Apr 2017

Temporal Resolution

One set of ice front positions per year.

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Parameter or Variable

Geometric ice front positions.

Parameter Description

Shapefiles of ice front locations for outlet glaciers in Greenland for 2000–01, 2005–06, 2006–07, 2007–08, 2008–09, 2012–13, 2014-15, 2015-16, and 2016-17 winter seasons. Beginning with the 2014-15 season, three new fields are included in the data. See Table 4 for a description of all data fields.

Table 4. Primary Data Attributes
Data Field Description Values
GlacierID Numerical ID assigned to each glacier (used consistently across all data sets)
  • 0 - 238
QualFlag
(included beginning with 2014 data)		 Quality flag indicator for digitized ice fronts of lower certainty or drawing from multiple image sources
  • 0 – no flag
  • 1 – digitized terminus position is estimated or uncertain (see Error Sources and Limitations section)
  • 2 - uncertain digitized terminus position was improved or verified using Landsat imagery
ImgSource
(included beginning with 2014 data)		 Satellite source of image used to digitize terminus position
  • Sentinel1
  • Landsat
DateRange
(pre-2014 data)		 Date range for images from full Greenland mosaic used to create digitized ice fronts DDMMMYYYY - DDMMMYYYY
DATE
(change to new format begins with 2014 data)		 Date of image used to digitize terminus position YYYYMMDD
GrnlndcNam
(updated* beginning with 2014 data and in GlacierIDv01.1.shp)		 Greenlandic glacier name *Values are standardized to match "New Greenlandic" attribute in database of Greenland glacier names (Bjørk et al., 2015)
Official_n
(included beginning with 2014 data and in GlacierIDv01.1.shp)		 Officially recognized glacier name Values are standardized to match "Official_n" attribute in database of Greenland glacier names (Bjørk et al., 2015)
GlacName (pre-2014 data) Glacier Name Glacier name (usually European glacier name)
AltName
(included beginning with 2014 data and in GlacierIDv01.1.shp)		 Alternative glacier name Includes foreign name or Old Greenlandic name (Bjørk et al., 2015), or other recognized names)

Sample Data Record

Figure 1 illustrates ice front positions for three Greenland glaciers during six winters.

Figure 1. Sample Data Visualization

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Software and Tools

These data can be readily accessed using GIS software such as ArcGIS and QGIS.

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Data Acquisition and Processing

Theory of Measurements

From 2000 through 2013, the terminus positions were created using 20 m resolution SAR Mosaics of Greenland. As of 2014, the positions were created using the SAR imagery from the Copernicus Sentinel-1 satellite and Landsat 8 panchromatic imagery.

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Data Acquisition Methods

See MEaSUREs Greenland Ice Sheet Mosaics from SAR Data and MEaSUREs Greenland Image Mosaics from Sentinel-1A and -1B, Version 2 for information on the base maps used to create this data set.

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Derivation Techniques and Algorithms

Terminus positions were digitized using mosaics created from RADARSAT satellite data through 2013, and as of 2014, they were created from Sentinel-1 and Landsat 8 satellite data. Positions were digitized for Greenland Ice Sheet outlet glaciers with terminus widths of roughly 1.5 km or greater. All glaciers that appear in each year's mosaic were digitized with few exceptions. For users of the data set, image quality varies and should be considered on a per-glacier basis. In cases where the terminus was highly fractured, the terminus position does not include fully detached (fractured) areas. For some glaciers, this determination is not clearly objective.

Number of glaciers in full data set: 238

Not all glaciers appear in each year due to limits in the satellite coverage; however, as of the 2014/15 winter season, all glaciers are included.

Table 5. Number of glaciers digitized per year
Data Year Number of glaciers digitized
2000/01 205
2005/06 203
2006/07 200
2007/08 208
2008/09 201
2012/13 206
2014/15 238
2015/16 238
2016/17 238

Error Sources and Limitations

Errors in digitized terminus location may occur due to:

  • image distortion due to local topography
  • difficulty distinguishing intact glacier ice from adjacent glacier or sea ice
  • highly fractured terminus area
  • resolution limits
  • manual digitization error

The digitization line is meant to cover roughly the full width of the active glacier terminus and the line ends do not necessarily indicate a junction between ice and rock or any other defined measure of a glacier edge. Therefore, this data set should not be used as a measure of glacier width.

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Sensor or Instrument Description

For information about the SAR systems used to construct the mosaics from which this data set is derived, see the Alaska Satellite Facility's SAR Basics web page, the Japan Aerospace Exploration Agency (JAXA) About ALOS - PALSAR site, and the European Space Agency's Copernicus Sentinel-1 site. Information on the Landsat-8 OLI sensor is available on the USGS web site.

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Version History

Version 1.2 was released in October 2017. Refer to Table 6 for this data set's version history:

Table 6. Version History
Version Description
V1.2 (October 2017) Added glaciers to two winters:
2006/2007 -- glaciers 90 and 91
2008/2009 -- glaciers 1-9, 90, and 91

V1.1 (August 2017) Minor changes include:
  • Added data for winters of 2014/2015, 2015/16, 2016/17
  • Added new parameter attributes for the new data
  • Added 29 new glaciers
  • Provided a new GlacierID file with added glaciers and updated attributes
V1 (September 2015) Initial release
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References and Related Publications

REFERENCES

Bjørk, A. A., L. M. Kruse, and P. B. Michaelsen. 2015. Brief communication: Getting Greenland's glaciers right – a new data set of all official Greenlandic glacier names. The Cryosphere 9(6): 2215-2218. doi: https://doi.org/10.5194/tc-9-2215-2015.

RELATED DATA COLLECTIONS

RELATED WEB SITES

Contacts and Acknowledgments

Investigator(s) Name and Title

Ian Joughin
University of Washington
Applied Physics Laboratory
1013 NE 40th Street
Box 355640
Seattle, WA 98105

Twila Moon
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA

Jonah Joughin
Jonahjoughin@gmail.com

Taryn Black
teblack@uw.edu

Acknowledgments: 

These data were generated through a grant from the NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) Program. Digitized ice fronts were created by Dr. Twila Moon. Contains modified Copernicus Sentinel data (2014-2017), acquired by the European Space Agency, distributed through the Alaska Satellite Facility, and processed by Joughin, I., T. Moon, J. Joughin, and T. Black.

Document Information

DOCUMENT CREATION DATE

29 September 2015

DOCUMENT REVISION DATE

October 2017

How To

Programmatically access data using spatial and temporal filters
This article provides a step-by-step getting started guide to utilizing an Application Programming Interface, or API, for programmatic access to data from the NSIDC Distributed Active Archive Center (DAAC) based on spatial and temporal filters. Programmatic access is provided via an HTTPS URL... read more
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