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Metadata Identifier: gov.noaa.ngdc.mgg.geophysics:G01433

Aggregation Info | Bands | Citations | Constraints | Coverage Descriptions | Dimensions | Extents | Formats | Geographic Bounding Box
Georectified Information | Georeferenceable Information | Identifiers | Instruments | Mediums | OnlineResources | Operations
Platforms | Process Steps | Range Elements | Reference Systems | Responsible Parties | Series | Sources | Spatial Grids | Temporal Extents

MD_DataIdentification

Count Component Title Abstract
1 Mexico Geoid Heights (MEXICO97) This 2' geoid height grid for Mexico, and North-Central America, is the MEXICO97 geoid model. The computation used about one million terrestrial and marine gravity measurements held in the NGS database as of March 1997. These gravity measurements were augmented by data contributions from NGA (former National Imagery and Mapping Agency), and satellite altimeter-derived gravity anomalies computed by Sandwell and Smith (1997). Large data gaps south of 20 degrees North latitude were filled with 15'x15' gravity values derived from the EGM96 global geopotential model. This helped control interpolation errors across the data gaps during the gridding of terrain corrected Bouguer anomalies. After gridding of the Bouguer anomalies, the Bouguer plate was restored, a degree 360 model of gravity anomalies (from EGM96) was removed, and the residual free-air anomalies in the data gaps (south of 20 degrees North Latitude) were zeroed. (This zeroing was found to be the best way currently available to yield a reasonable geoid in the data gaps). The residual Faye anomalies were converted to residual co-geoid undulations through a 1-D FFT formulation of Stokes' integral, and finally the EGM96 undulation model was restored, and the indirect effect applied. This means that in the data gaps, long wavelength information is provided by EGM96, short wavelength information is provided by the 2'x2' DTED (during the application of the indirect effect), but medium wavelength information (usually provided by gravity measurements) is missing altogether. Although the exact accuracy of the geoid in the data gaps is difficult to ascertain, the quoted accuracy for EGM96 (which is the primary source of geoid information in the data gaps) is below 50 cm in these areas. The gravity values are based on the International Gravity Standardization Net 1971 (IGSN71). The geoid heights are referred to the Geodetic Reference System 1980 (GRS80) ellipsoid, centered at the origin of the International Terrestrial Reference Frame 1994 (ITRF94(1996.0)). Additional information is available at: http://www.ngs.noaa.gov/GEOID/MEXICO97/ We are particularly grateful to NGA (former National Imagery and Mapping Agency) for their assistance and their data contributions.
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SV_Identification

none found
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CI_Citation

Count Component Title Date Citation Identifier
1 Mean Sea Level depth
  • 2012-08-10
2 Mexico Geoid Heights (MEXICO97)
  • 1999-01-01
1 GCMD Data Center Keywords NASA/GCMD Data Center Keywords
    1 GCMD Location Keywords NASA/GCMD Location Keywords
      1 NASA/GCMD Science Keywords NASA/Global Change Master Directory (GCMD) Earth Science Keywords
      • 2007-04
      1 Uncontrolled Keywords
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        CI_Series

        none found
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        CI_ResponsibleParty

        Count Component Individual Organization Position Email Role Linkage
        1 resourceProvider http://www.epsg-registry.org/export.htm?gml=urn:ogc:def:crs:EPSG::5715
        2 GCMD Valids custodian http://gcmd.nasa.gov/learn/keyword_list.html
        2 Brian Meyer Brian Meyer DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce Brian.Meyer@noaa.gov pointOfContact
        1 User Services (publisher) DOC/NOAA/NESDIS/NGDC - National Geophysical Data Center User Services ngdc.info@noaa.gov publisher
        1 User Services (originator) DOC/NOAA/NESDIS/NGDC - National Geophysical Data Center User Services ngdc.info@noaa.gov originator
        1 User Services DOC/NOAA/NESDIS/NGDC - National Geophysical Data Center User Services ngdc.info@noaa.gov distributor
        1 National Geodetic Survey DOC/NOAA/NOS/NGS > National Geodetic Survey, National Ocean Service, NOAA, U.S. Department of Commerce ngs.cors@noaa.gov custodian
        1 EPSG Registry European Petroleum Survey Group publisher http://www.epsg-registry.org/
        2 GCMD User Support Office NASA GCMD User Support Office gcmduso@gcmd.gsfc.nasa.gov custodian http://gcmd.nasa.gov/MailComments/MailComments.jsf?rcpt=gcmduso
        1 NASA/GSFC/SED/ESD/GCDC/GCMD > Global Change Master Directory, Global Change Data Center, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA resourceProvider http://gcmd.gsfc.nasa.gov/Resources/valids/archives/keyword_list.html
        1 Susan Mclean Susan McLean DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce Susan.McLean@noaa.gov pointOfContact
        1 Susan Mclean (processor) Susan McLean DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce Susan.McLean@noaa.gov processor
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        CI_OnlineResource

        Count Component Linkage Name Description Function
        1 http://gcmd.gsfc.nasa.gov/Resources/valids/archives/keyword_list.html GCMD Keywords, Version 6.0.0.0.0 Thesuarus for earth science keywords and associated directories hosted and maintained by NASA. information
        2 http://gcmd.nasa.gov/MailComments/MailComments.jsf?rcpt=gcmduso GCMD Feedback Form Have a Comment for the GCMD? information
        2 GCMD Keyword Page http://gcmd.nasa.gov/learn/keyword_list.html GCMD Keywords Page This page describes the NASA GCMD Keywords, how to reference those keywords and provides download instructions. information
        1 http://www.epsg-registry.org/ European Petroleum Survey Group Geodetic Parameter Registry Registry that accesses the EPSG Geodetic Parameter Dataset, which is a structured dataset of Coordinate Reference Systems and Coordinate Transformations. search
        1 http://www.epsg-registry.org/export.htm?gml=urn:ogc:def:crs:EPSG::5715 MSL depth GML for Vertical CRS in EPGS Registry. information
        1 http://www.ngdc.noaa.gov/mgg/fliers/se-0703.html
        1 http://www.ngdc.noaa.gov/mgg/gravity/1999/document/html/tablegri.html
        1 http://www.ngdc.noaa.gov/mgg/gravity/1999cd.html
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        MD_Identifier or RS_Identifier

        Count Component Code
        1 urn:ogc:def:crs:EPSG::5715
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        EX_Extent

        Bounding Box Temporal Extent
        Count Component Description West East North South Start End
        1 -119 -75 33 14
        1
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        EX_GeographicBoundingBox

        Count Component West East North South
        1 -119 -75 33 14
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        EX_TemporalExtent

        Count Component Start End
        2
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        MD_Format

        Count Component Name Version specification
        1 Binary
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        MD_Medium

        Count Component Name mediumFormat mediumNote
        1 cdRom iso9660 iso9660
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        MD_Constraints

        Count Component Use Limitation
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        MD_ReferenceSystem

        Count Component Code Authority Title
        1 MSL urn:ogc:def:crs:EPSG::5715 Mean Sea Level depth
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        MD_GridSpatialRepresentation

        Count Component Number of Dimensions Cell Geometry Code
        1 2 area
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        MD_Georeferenceable or MI_Georeferenceable

        none found
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        MD_Georectified or MI_Georectified

        none found
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        MD_Dimension

        Count Component Name Code Size
        1 row 571
        1 column 1321
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        MD_CoverageDescription or MI_CoverageDescription

        Count Component Attribute Description Content Type
        1
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        MD_Band or MI_Band

        Count Component Identifier Descriptor
        1 Gravity grid value Value, in milligals of an observed gravity station value, after various corrections have been applied to the value.
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        MI_RangeElementDescription

        none found
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        MD_AggregateInformation

        none found
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        LE_Source or LI_Source

        Count Component Title Date Description
        1 Mexico Geoid Heights (MEXICO97) Source Contribution: Gravity survey data Source Type: varies
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        LE_ProcessStep or LI_ProcessStep

        Count Component DateTime Description
        1 All data were processed by the source before being forwarded to the National Geophysical Data Center
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        MI_Operation

        none found
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        MI_Platform

        none found
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        MI_Instrument

        none found
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