GLOBE (Global Land One-km Base Elevation)

Description

GLOBE is an international effort to create a global digital elevation model (DEM) on a nominal 1-kilometer grid. Data from a variety of sources was compiled and independently peer-reviewed to provide 30 arcsecond grid spacing, which corresponds to approximately one kilometer near the equator. GLOBE Version 1.0 was completed and released in 1999. GLOBE is an activity of the Committee on Earth Observation Satellites (CEOS), and is part of Focus 1 of the International Geosphere-Biosphere Programme's Data and Information System (IGBP-DIS).

GLOBE coverage is divided into 16 tiles in a 4 x 4 layout. Each tile spans 90 degrees of longitude has 10800 columns. Tiles bordering the equator (4 above and 4 below) span 50 degrees of latitude, while the remaining tiles (4 above and 4 below) span 40 degrees. (Note that 50 + 40 = 90 degrees north and south of the equator.) Bathymetric data is not yet included but is planned for a future version of GLOBE.

Note - During the creation of the GLOBE data set, another global, 30-arcsecond elevation data set called GTOPO30 was also created, but the two projects differ in a variety of ways.

Grid Information

Coord. System: Geographic decimal degrees, fixed-angle
Cell Size: 30 arcseconds (1/120 of a degree or 1/2 arcminute)
Tile Dimensions: 10800 columns x 6000 rows (tiles bordering equator, 8 tiles)
10800 columns x 4800 rows (all other tiles, 8 tiles)
Tile Span: 90 degrees x 50 degrees (tiles bordering equator, 8 tiles)
90 degrees x 40 degrees (all other tiles, 8 tiles)
Data Type: 2-byte integer, signed
Horizontal Datum: WGS 84
Vertical Datum: mean sea level
Vertical Units: meters
Nodata Value: -500 (ocean)
Formats: Flat binary (row major, no header), LSB.
Georef. info in separate header files; several formats available.

Data Source

National Geophysical Data Center (NGDC) of the National Oceanic and Atmospheric Administration (NOAA)

Availability

The GLOBE data set is available online from NOAA/NGDC and on a collection of CD-ROMs.

Web Sites

Main page: http://www.ngdc.noaa.gov/mgg/topo/globe.html

Download Tiles: http://www.ngdc.noaa.gov/mgg/topo/gltiles.html

Documentation: http://www.ngdc.noaa.gov/mgg/topo/report/index.html

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