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Summary
ABSTRACT: The Decade of North American Geology (DNAG) gravity grid values, spaced at 6 km, were used to produce the Gravity Anomaly Map of North America (1987; scale 1:5,000,000). Considerable caution should be exercised when using these gridded data in regions of sparse coverage (for example, deep oceanic areas). The spatial distribution of the original data from which the grid was ... generated is shown on sheet 5 of the published map. Note: There are no gridded data values for Mexico.

PURPOSE: To provide easy access to global and regional gravity data and related models for scientific studies.

SUPPLEMENTAL INFORMATION: Note that this Spherical Transverse Mercator projection is a unique projection used for the DNAG map series. In addition to giving the Bounding Coordinates in latitude and longitude, the limits of coverage for the gridded and projected data sets are also given in units of measure of the projection. This is usually the distance from a central meridian (the x-coordinate), or base latitude (the y-coordinate), in meters or kilometers of the given projection. For this data set those boundaries are: The Western-most boundary: -4480 kilometersThe Eastern-most boundary: 4500 kilometersThe Northern-most boundary: 9280 kilometersThe Southern-most boundary: 700 kilometers

CURRENTNESS REFERENCE: Ground Condition

SPATIAL DATA ORGANIZATION INFORMATION
Direct Spatial Reference: Raster
Raster Object Type: Grid Cell
Row Count: 1430
Column Count: 1495

SPATIAL REFERENCE INFORMATION - GEODETIC MODEL
Horizontal Datum Name: Unknown
Ellipsoid Name: Unknown
Semi-major Axis: 9999.9
Denominator of Flattening Ratio: 9999.9

Geographic Coverage Spatial coordinates   

N: 81.17

S: 5.17

E: -10.75

W: 170.0

Data Set Citation

Dataset Creator: DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce (comp). Dataset Title: DNAG Gravity Data Dataset Release Date: 1999 Dataset Release Place: Boulder, CO Dataset Publisher: National Geophysical Data Center Version: 1999 Edition Online Resource: http://www.ngdc.noaa.gov/mgg/gravity/

Location Keywords

CONTINENT > NORTH AMERICA

Science Keywords

SOLID EARTH > GEODETICS/GRAVITY > CONTROL SURVEYS SOLID EARTH > GEODETICS/GRAVITY > GRAVITATIONAL FIELD SOLID EARTH > GEODETICS/GRAVITY > GRAVITY SOLID EARTH > GEODETICS/GRAVITY > REFERENCE SYSTEMS SOLID EARTH > GEODETICS/GRAVITY > SATELLITE ORBITS

ISO Topic Category

GEOSCIENTIFIC INFORMATION

Project

ESIP > Earth Science Information Partners Program

Quality
ATTRIBUTE ACCURACY REPORT: Gravity data values are the result of the measurement of small variations in the gravitational field of the Earth. The magnitudes and ranges of these variations are well known in the potential field discipline.

LOGICAL CONSISTENCY REPORT: Not available

COMPLETENESS REPORT: Not available

HORIZONTAL POSITIONAL ACCURACY REPORT: ... Horizontal accuracy varies from source contributor to source contributor. However, horizontal positions are usually taken from topographic maps of the area being surveyed. Accuracy may range up to +/- 100 feet.

VERTICAL POSITIONAL ACCURACY REPORT: Vertical accuracy varies from source contributor to source contributor. However, vertical positions are usually taken from topographic maps of the area being surveyed, monumented benchmark locations, or they are determined by the use of the Global Positioning System (GPS). Accuracy may range from meters to centimeters or better.

LINEAGE/PROCESS STEP:
PROCESS DESCRIPTION: All data were processed by the source before being forwarded to the National Geophysical Data Center
PROCESS DATE: Unknown

LINEAGE/SOURCE INFORMATION:
ORIGINATOR: Geological Society of America .
TITLE: DNAG Gravity Data . Unknown .
TYPE OF SOURCE MEDIA: varies .
SOURCE TIME PERIOD OF CONTENT/BEGINNING TIME: Unknown .
SOURCE TIME PERIOD OF CONTENT/ENDING TIME: Unknown .
SOURCE CURRENTNESS REFERENCE: Release date .
SOURCE CITATION ABBREVIATION: dnaggrav.bin .
SOURCE CONTRIBUTION: Gridded gravity data

Access Constraints
ACCESS CONSTRAINTS: None

DISTRIBUTION LIABILITY: Disclaimer: While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

CUSTOM ORDER PROCESS: Contact Data Center for information.

Use Constraints
If you use this data, please cite the National Geophysical Data Center and the originator of the data.

Ancillary Keywords

WDC/SEG, BOULDER > World Data Center for Solid Earth Geophysics, Boulder DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce Free Air Anomaly Gridded Gravity Land Gravity Observed Gravity

Data Set Progress

COMPLETE

Data Center

National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce Data Center URL: http://www.ngdc.noaa.gov/ Dataset ID: ______Gravity ____ Data Center Personnel Name: NGDC USER SERVICES Phone: (303) 497-6826 Fax: (303) 497-6513 Email: ngdc.info at noaa.gov Contact Address: NOAA/NESDIS/NGDC E/GC 325 Broadway City: Boulder Province or State: CO Postal Code: 80305-3328 Country: USA

Distribution

Distribution Size: 4275700 Distribution Format: Binary Fees: Depends on the data set

Personnel

SUSAN MCLEAN Role: TECHNICAL CONTACT Role: DIF AUTHOR Phone: (303) 497-6478 Fax: (303) 497-6513 Email: Susan.McLean at noaa.gov Contact Address: NOAA/NESDIS/NGDC E/GC2 325 Broadway City: Boulder Province or State: CO Postal Code: 80305-3328 Country: USA

Related URL

Link: GET DATA Link: VIEW EXTENDED METADATA Description: View Source Metadata document from the Metadata Manager and Repository (NMMR). Link: VIEW RELATED INFORMATION Link: VIEW RELATED INFORMATION Link: VIEW RELATED INFORMATION

Creation and Review Dates

DIF Creation Date: 2008-02-07 Last DIF Revision Date: 2008-02-29 Future DIF Review Date: 2001-10-10

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