5.A.xi. Antarctic Digital Database

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Primary Developer:		Scientific Committee for Antarctic Research
Title:		Antarctic Digital Databse
Publication Date:		1993
Bibliographic Citation:		Scientific Committee for Antarctic Research, 1993. Antarctic Digital Database on CD-ROM. Scott Polar Research Institute, Cambridge, England.
Post-processing:		U.S. Geological Survey (for GTOPO30); NOAA/National Geophysical Data Center (for GLOBE).
Bibliographic Citation for Post-processed DEM:	*	USGS, 1996b. 30 Arc-second-gridded Digital Elevation Model Derived from the Antarctic Digital Database (SCAR, 1993). USGS, EROS Data Center, Sioux Falls, South Dakota. (In USGS, 1997; also in GLOBE Task Team and others, 1999.)
	**	Hasatings, David A., and Paula K. Dunbar, 1999. Global Land One-kilometer Base Elevation (GLOBE) Digital Elevation Model, Documentation, Volume 1.0. KGRD 34, NOAA, National Geophysical Data Center, Boulder, Colorado, pp. 55-56.
Source/Lineage Category:		18

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The Antarctic Digital Database (ADD) was produced under the auspices of the Scientific Committee on Antarctic Research (SCAR). This project compiled topographic contour maps from eleven nations into one collection. ADD vector data were compiled from maps ranging in scale from 1:200,000 to 1:5,000,000.

The detail, density, and interval of the contours in ADD vary widely, with the more detailed data near the coastline and very generalized data in the interior of the continent. The coastline was updated using 1:1,000,000-scale satellite images. Detailed documentation and metadata provided in ADD identifies the map scale from which each contour line was extracted. The data base is available on CD-ROM.

Digital contours and coastlines from ADD were used as source material for Antarctica. They were converted to DEMs at USGS, using contour-to-grid techniques. That procedure is described in Section 5.A.vii.

GLOBE quality control detected edge-effect errors in the USGS adaptation of ADD. The westernmost column bordering on 180^oW longitude, easternmost two columns, and southernmost row bordering on the South Pole contained nominal flag values instead of actual elevations. These errors were corrected by NGDC for GLOBE.

Cell-center registration; contour-to-grid value computed. Graphic describing georeferencing and sampling for ADD conversion.

Plate 30. Click on the image to view larger size.

Plate 30 shows a broad peak about 3000m elevation, typical for ice caps. The precipitous drop in the histogram at 4050m, with very few elevation values trailing off to about 4700m is notable, as is the modest trough in values between 0 and 200m elevation. Spikes at every 100m of elevation from 200 through 4000m suggests 100m contour intervals for significant parts of the map. However, the data base is documented as having various horizontal scales and levels of contour detail.

There are several DEMs and spot elevation data sets derived from satellite altimetry for Antarctica. Several of these are being evaluated for future versions of GLOBE.