Release Date: January 12, 2009
The borders used to represent Antarctica in the Atlas of the Cryosphere (http://nsidc.org/data/atlas/) have been updated with an improved set of coastlines, which are higher in resolution, more current, and more accurate. Antarctica can be represented by a set of three borders; note that none of these includes the surrounding sea ice, whose extent fluctuates seasonally:
Table 1. Antarctic borders grounding line outlines the area of Antarctica that is underlain by solid ground rather than ocean, which includes the ice sheet as well as any exposed ground; this excludes the surrounding ice shelves. The grounding line is often used to represent the continent and political boundary of Antarctica. islands outlines the islands surrounding the ice sheet, also underlain by solid ground. coastline or shoreline outlines the outermost permanent features of Antarctica that are bordered by the ocean, including the ice sheet, exposed ground, and the surrounding ice shelves.
The Digital Chart of the World (DCW) (NIMA 1992) was previously used to represent the grounding line and islands in the Atlas of the Cryosphere, while the Global Self-consistent, Hierarchical, High-resolution Shoreline (GSHHS) (Wessel and Smith 1996) was used to respresent the coastline or shoreline. In their place, a 250-m resolution set of borders is now used instead, which were hand-digitized from the Moderate-resolution Imaging Spectroradiometer (MODIS) Mosaic of Antarctica (MOA) image map produced and distributed by the National Snow and Ice Data Center (NSIDC):
Below are example images of both the old and new Antarctic borders, produced with the Atlas of the Cryosphere; click on any of the images in this table for a slightly bigger image:
Table 2. Example images Old Coastlines: New Coastlines:
Old (left) and new (right) Antarctic borders used in the Atlas of the Cryosphere; the regions depicted from top to bottom include: the entire ice sheet, Antarctic peninsula, Ronne ice shelf, and Ross ice shelf. Click on any image above to view a larger version.
In addition to accessing these Antarctic borders through the Atlas of the Cryosphere Web interface, they are also available remotely in a variety of formats and map projections through Open Geospatial Consortium (OGC) protocols, as in the following examples:
We welcome your feedback on this project. If you have questions, comments or suggestions, please contact NSIDC User Services at +1.303.492.6199, firstname.lastname@example.org, or via our online contact form. The development of this map server application was supported by NASA's Earth Observing System (EOS) Program under contract NAS5-03099 and was developed using MapServer, an Open Source development environment for building spatially-enabled internet applications. The Atlas of the Cryosphere was developed by John Maurer. Future updates will continue to be announced on this RSS feed.