Chapter 1. Executive Summary
This is the first version of documentation for the Global Land One-kilometer Base Elevation (GLOBE) data set. GLOBE is an internationally designed, developed, and independently peer-reviewed global digital elevation model (DEM), at a latitude-longitude grid spacing of 30 arc-seconds (30"). This report describes the history of the GLOBE project, the candidate data sets, data compilation techniques, organization, and use of the data base. The data are available on CD-ROM and the World Wide Web.
The previous standards for global digital elevation models (DEMs) are ETOPO5 (NGDC, 1988) and TerrainBase (Row and Hastings, 1994; Row and others, 1995), which were at 5 arc-minute (5') gridding. Higher resolution DEMs exist for parts of the world (Gittings, 1997). However, when GLOBE was conceived, no DEM of higher resolution was known that covered more than two-thirds of Earth's land surface. That DEM (NIMA, various dates) and most higher-resolution DEMs outside the United States are restricted by copyright or other limitation on their distribution.
Two global DEMs have been produced at 30" gridding during the design and development of GLOBE. The Jet Propulsion Laboratory, a Federally-funded Research and Development Center operated by the California Institute of Technology for the National Aeronautics and Space Administration (NASA), developed a DEM from Digital Terrain Elevation (DTED) and other sources, for internal use in support of NASA satellite missions. Separately, the U.S. Geological Survey developed a DEM called GTOPO30. Both of these data sets have provided important pieces of GLOBE Version 1.0. However, GLOBE Version 1.0 differs from such projects:
GLOBE data are suitable for many regional and continental applications, such as:
Caveats: Note that GLOBE Version 1.0, like other digital topographic data, are insufficiently accurate over their full global extent to be taken too literally for mission-critical applications. They must always be interpreted with extreme caution. They should not be used exclusively in mission-critical or life-critical applications. Nevertheless, GLOBE Version 1.0, with its present 30" gridding, multiple sources, and documentation designed to inform users of the character of such data, is a remarkable improvement over previously available data and ancillary materials. It greatly exceeds the original expectations of its developers. This document contains discussions about data quality; caveats are concentrated in Sections 6 and 12 of this report.
GLOBE remains in active development. Peer review continues to be an integral part of the GLOBE process; please see our peer review site on the World Wide Web linked from http://www.ngdc.noaa.gov/mgg/topo/globe.html. Future versions of GLOBE should be even more valuable, as they are expected to include:
GLOBE has been creative in negotiating ways to release new DEMs to the public:
GLOBE cites sources of data, and can mention, when appropriate, that certain sources can directly supply higher quality data. We hope you will contact the GLOBE Secretariat about the benefit to yourselves (and the public) from contributing to the GLOBE data base. Please contact:
David Hastings, Secretary of GLOBE
Note: The Web-based version of this documentation will receive more frequent updates than the printed version. Bookmark http://www.ngdc.noaa.gov/mgg/topo/report/.