[Keyword='Environmental Monitoring > Environmental Measurements > Elevation']
U.S. NAVY ELEVATION FOR ZAMBIA (10 MINUTES LAT./LONG. RESAMPLED).Entry ID: GNVd0072_104
Abstract: UNEP/GRID Documentation Summary for Data Set:
U. S. Navy (FNOC) 10-Minute Elevation
The U. S. Navy Fleet Numerical Oceanography Center (FNOC; Monterey,
Ca.) was the original producer of the 10-Minute Elevation or Terrain
data set. The FNOC began creating this data set in the mid-1960s, and
their work on it continued into the early 1970s. The main sources of
the data were the U.S. Department ... of Defense (DoD) Operational
Navigation Charts (ONC) at a scale of 1:1000000. Where ONCs were not
available, other maps such as the Jet Navigation Charts and World
Aeronautical Charts were used. The elevation values in the data set
were estimated from contour lines on these charts. Isometric graphs
were made for quality control, in order to check the terrain features.
Further corrections were made at a later stage, after the data set had
been transferred to the National Center for Atmospheric Research
(NCAR) in Boulder, Co. USA. More recent quality checking at the
National Geographic Data Center (NGDC, same location) revealed
numerous additional errors, mostly in the Southern Hemisphere.
However, at the time of its release in 1985, it was the "best" digital
terrain product available having full coverage at a global scale.
The U.S. Navy Elevation data set has a spatial resolution of every ten
minute latitude/longitude crossing on the global grid (approximately
18 km. sq. cell size, or six pixels square per degree). The coded
values are in terms of 100 foot contour intervals, which range between
0 and 25,500. Unlike the 'ETOPO-5' data set, the U.S. Navy Elevation
data does not include bathymetry (i.e., it covers only land areas).
Land below 0 feet altitude has a value of zero, while most inland
water bodies have correct elevation values (with some major exceptions
such as the Caspian Sea, which is coded as zero).
The GRID-supplied data file is 16 bits (two bytes per element), and
consists of 1080 lines by 2160 elements (4320 bytes with two bytes per
pixel). It has an origin at 90 degrees North latitude and 180 West
longitude, and it extends to 90 degrees South latitude and 180 degrees
East longitude. The GRID-supplied data file comprises 4.67 Megabytes.
The original FNOC 10-Minute Elevation data set included four
additional variables (other than terrain height). These were
Significant Ridges; Characteristics of the Terrain (primary and
secondary); Percentage of Water and Percentage of Urban Development.
The GRID version of this data set, however, includes only the
10-Minute Elevation values.
GRID's source of this data set was NCAR, and the primary literature
reference is "Cuming, Michael J. and Barbara A. Hawkins, 1981.
TERDAT: The FNOC System for Terrain Data Extraction and Processing.
Technical Report Mil Project M-254 (second edition). Prepared for
USN/FNOC and published by Meteorology International Inc."
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Access Constraints Public
Role: TECHNICAL CONTACT
Email: Hy.Dao at unep.org
Head of Metadata & Socio-Economics Unit
Postal Code: 1219
Creation and Review Dates
DIF Creation Date: 2005-11-07
Last DIF Revision Date: 2005-11-07