1:250,000 Scale Digital Elevation Models (DEM) from the U.S. Geological SurveyEntry ID: USGS_DEM250K
Abstract: A digital elevation model (DEM) consists of an array of elevations for ground positions that are usually at regularly spaced intervals.
The 1-degree DEM provides coverage in 1- by 1-degree blocks and is available for all of the contiguous United States, Hawaii, and most of Alaska. The basic elevation model is produced by the Defense Mapping Agency (DMA) using cartographic and photographic ... sources.
The 1-degree DEM consists of a regular array of elevations referenced horizontally on the geographic coordinate (latitude/longitude) system of the World Geodetic System 1984 Datum. Elevation data located on the degree lines (all four sides) correspond with the same profiles on adjoining DEM blocks.
Elevations are in meters relative to mean sea level. Spacing of the elevations along and between each profile is 3 arc-seconds with 1,201 elevations per profile. The only exception are DEMs in Alaska, where the spacing and number of elevations per profile varies depending on the latitudinal location of the DEM. Latitudes between 50 and 70 degrees north have spacings at 6 arc-seconds with 601 elevations per profile and latitudes greater than 70 degrees north have spacings at 9 arc-seconds with 401 elevations per profile.
As of November 14, 2006, the USGS no longer offers Digital Elevation Models. For the most recent elevation coverage, please see the National Elevation Dataset. http://ned.usgs.gov/
Data Set Citation
Dataset Title: 1:250,000 Scale Digital Elevation Models (DEM)
Dataset Publisher: EROS Data Center, USGS
Latitude Resolution: 1 degree
Longitude Resolution: 1 degree
Horizontal Resolution Range: 100 km - < 250 km or approximately 1 degree - < 2.5 degrees
TERRESTRIAL HYDROSPHERE > SURFACE WATER > HYDROPATTERN
TERRESTRIAL HYDROSPHERE > SURFACE WATER > LAKES
TERRESTRIAL HYDROSPHERE > SURFACE WATER > RIVERS/STREAMS
LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION > CONTOUR MAPS
LAND SURFACE > TOPOGRAPHY > LANDFORMS
LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION > TOPOGRAPHICAL RELIEF MAPS
LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION
Access Constraints None.
Use Constraints There is no guarantee of warranty concerning the accuracy of these data. Users should be aware that temporal changes may have occurred since the data was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of their limitations. Acknowledgement of the originating agencies would be appreciated in products derived from these data. Any user who modifies the data set is obligated to describe the types of modifications they perform. User specifically agrees not to misrepresent the data set, nor to imply that changes made were approved or endorsed by the U.S. Geological Survey. Please refer to http://www.usgs.gov/privacy.html for the USGS disclaimer.
Data Set Progress
Distribution Media: Digital Download from http://ned.usgs.gov
Role: DIF AUTHOR
Phone: (301) 614-6898
Email: Tyler.B.Stevens at nasa.gov
NASA Goddard Space Flight Center Global Change Master Directory
Province or State: MD
Postal Code: 20771
Digital Elevation Models, National Mapping Program Technical
Instructions, Data Users Guide 5, U.S. Geological Survey, Second
Printing (Revised), Reston, Virginia, 1990.
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date: 2001-02-09
Last DIF Revision Date: 2015-02-12
Future DIF Review Date: 2004-05-06