GTOPO30 (Global Topography 30-Arcsecond)


GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing of 30 arcseconds (about 1 kilometer at the equator). GTOPO30 was developed through a collaborative effort led by staff at the USGS EROS Data Center. NASA and several other organizations around the world contributed to the project, which was completed in late 1996. The data set provides complete global coverage divided into 33 tiles. The GLOBE data set offers similar coverage but differs in several respects.

Latitudes between -90 and -60 correspond to Antarctica, which is covered by 6 tiles. The data for Antarctica is also available in a polar stereographic projection consisting of a single tile that has 5400 columns and 5400 rows and a grid spacing of 1000 meters.

Grid Information

Coord. System: Geographic decimal degrees, fixed-angle
Cell Size: 30 arcseconds (1/120 of a degree or 1/2 arcminute)
Tile Dimensions: 4800 columns x 6000 rows (latitudes between -60 and 90, 27 tiles)
7200 columns x 3600 rows (latitudes between -90 and -60, 6 tiles)
Tile Span: 40 degrees x 50 degrees (latitudes between -60 and 90, 27 tiles)
60 degrees x 30 degrees (latitudes between -90 and -60, 6 tiles)
Data Type: 2-byte integer, signed
Horizontal Datum: WGS 84
Vertical Datum: mean sea level
Vertical Units: meters
Nodata Value: -9999 (ocean)
Formats: Flat binary (row major, no header), MSB
Georef. info. in a separate ASCII header (HDR) file.

Data Source

EROS Data Center (EDC) of the US Geological Survey (USGS) of the US Department of the Interior

Data Availability

All of the tiles can be previewed and downloaded free of charge from EROS Data Center, from the web site listed below. The product is also available on 5 CD-ROMs.

Web Sites

Main page:

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