Abstract:: The U.S. Geological Survey has developed a National Elevation Dataset (NED). The NED is a seamless mosaic of best-available elevation data. The 7.5-minute elevation data for the conterminous United States are the primary initial source data. In addition to the availability of complete 7.5-minute data, efficient processing methods were developed to filter production artifacts in the existing data, convert to the NAD83 datum, edge-match, and fill slivers of missing data at quadrangle seams. One of the effects of the NED processing steps is a much-improved base of elevation data for calculating slope and hydrologic derivatives. The specifications for the NED 1 arc second and 1/3 arc second data are: Geographic coordinate system Horizontal datum of NAD83, except for AK which is NAD27 Vertical datum of NAVD88, except for AK which is NAVD29 Z units of meters
Purpose:: Geospatial elevation data are utilized by the scientific and resource management communities for global change research, hydrologic modeling, resource monitoring, mapping, and visualization applications.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19990201
Ending_Date: unknown

Currentness_Reference: publication date

Status:

Progress:
Maintenance_and_Update_Frequency:

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -120.988395
East_Bounding_Coordinate: -112.451420
North_Bounding_Coordinate: 42.939548
South_Bounding_Coordinate: 34.305719

Keywords:

Theme:

Theme_Keyword_Thesaurus: GCMD Parameter Keywords
Theme_Keyword: EARTH SCIENCE
Theme_Keyword: LAND SURFACE
Theme_Keyword: TOPOGRAPHY
Theme_Keyword: LANDFORMS
Theme_Keyword: TERRAIN ELEVATION
Theme_Keyword: 1-DEGREE DEM
Theme_Keyword: 2 ARC-SECOND DEM
Theme_Keyword: 7.5-MINUTE DEM
Theme_Keyword: CARTOGRAPHY
Theme_Keyword: DEM
Theme_Keyword: DIGITAL ELEVATION MODEL
Theme_Keyword: DIGITAL MAPPING
Theme_Keyword: EDC
Theme_Keyword: EROS
Theme_Keyword: GEODATA
Theme_Keyword: GIS
Theme_Keyword: MAPPING
Theme_Keyword: RASTER
Theme_Keyword: USGS

Place:

Place_Keyword_Thesaurus: GCMD Location Keywords
Place_Keyword: NORTH AMERICA
Place_Keyword: UNITED STATES
Place_Keyword: UNITED STATES OF AMERICA

Access_Constraints: none

Use_Constraints:

None. Acknowledgement of the originating agencies would be appreciated in products derived from these data.

Native_Data_Set_Environment:

Microsoft Windows 2000 Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 8.2.0.700

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Raster_Object_Information:

Raster_Object_Type: Pixel
Row_Count: 28887
Column_Count: 18749
Vertical_Count: 1

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Map_Projection:

Map_Projection_Name: Albers Conical Equal Area

Albers_Conical_Equal_Area:

Standard_Parallel: 29.500000
Standard_Parallel: 45.500000
Longitude_of_Central_Meridian: -96.000000
Latitude_of_Projection_Origin: 23.000000
False_Easting: 0.000000
False_Northing: 0.000000

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: row and column

Coordinate_Representation:

Abscissa_Resolution: 30.000000
Ordinate_Resolution: 30.000000

Planar_Distance_Units: meters

Geodetic_Model:

Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: Geodetic Reference System 80
Semi-major_Axis: 6378137.000000
Denominator_of_Flattening_Ratio: 298.257222

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: EROS Data Center
Contact_Person: Customer Services Representative

Contact_Address:

Address_Type: mailing and physical address
Address: U.S. Geological Survey EROS Data Center
City: Sioux Falls
State_or_Province: South Dakota
Postal_Code: 57198
Country: USA

Contact_Voice_Telephone: 605-594-6151

Contact_Facsimile_Telephone: 605-594-6589

Contact_Electronic_Mail_Address: custserv@edcmail.cr.usgs.gov

Resource_Description: National Elevation Dataset (NED)

Distribution_Liability:

Although these data have been processed successfully on a computer system at the U.S. Geological Survey, EROS Data Center, no warranty expressed or implied is made by either regarding the utility of the data on any system, nor shall the act of distribution constitute any such warranty. The USGS will warrant the delivery of this product in computer-readable format and will offer appropriate adjustment of credit when the product is determined unreadable by correctly adjusted computer peripherals, or when the physical medium is delivered in damaged condition. Requests for adjustments of credit must be made within 90 days from the date of this shipment from the ordering site.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Transfer_Size: 0.000

Metadata_Reference_Information:

Metadata_Date: 19990211

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: EROS Data Center
Contact_Person: Customer Services Representative

Contact_Address:

Address_Type: mailing and physical address
Address: U.S. Geological Survey EROS Data Center
City: Sioux Falls
State_or_Province: South Dakota
Postal_Code: 57198
Country: USA

Contact_Voice_Telephone: 605-594-6151

Contact_Facsimile_Telephone: 605-594-6589

Contact_Electronic_Mail_Address: custserv@edcmail.cr.usgs.gov

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time

Metadata_Extensions:

Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>
Profile_Name: ESRI Metadata Profile

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Metadata:

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