gov.noaa.nmfs.inport:39739 eng UTF8 model Other National Geodetic Survey resourceProvider NGS Communications and Outreach Branch (301) 713-3242 (301) 713-4172 ngs.infocenter@noaa.gov pointOfContact 2025-11-26T15:02:30 ISO 19115-2 Geographic Information - Metadata Part 2 Extensions for imagery and gridded data ISO 19115-2:2009(E) EPSG::4269 EPSG::5703 Geoid Height and Deflections of the Vertical Models Geoid Models 1996 creation 2019 revision 2013 publication NOAA/NMFS/EDM 39739 https://www.fisheries.noaa.gov/inport/item/39739 WWW:LINK-1.0-http--link Full Metadata Record View the complete metadata record on InPort for more information about this dataset. information https://geodesy.noaa.gov/GEOID/ WWW:LINK-1.0-http--link NGS GEOID Homepage Landing page for NGS GEOID and DEFLEC models. download https://doi.org/10.25923/pc79-0q29 WWW:LINK-1.0-http--link GEOID 18 Technical report for GEOID18 and DEFLEC18. download In Gauss' words, the geoid is "the mathematical figure of the Earth". This figure is an equipotential surface coincident with the idealized mean sea surface. The geoid can be computed from the geodetic boundary value problems that use gravity data as its boundary value. A geoid model computed using gravity data is called a gravimetric geoid. On the other hand, geoid height at bench marks can also be computed using data from spirit leveling and the Global Positioning System (GPS). A geoid model that is fixed to the GPS/leveling data is called a hybrid geoid. Both geoid models can serve as the zero-height-surface of a country's height system by selection. To satisfy this need, National Geodetic Survey has published a series of geoid models (https://geodesy.noaa.gov/GEOID). The vast majority of navigation and positioning applications utilize a hybrid geoid model with the latest model being GEOID18 for CONUS and Puerto Rico/U.S. Virgin Islands and GEOID12B for all other states and territories of the United States. The corresponding gravimetric geoid for these regions is xGEOID19B and USGG2012, respectively. All models are provided at 1 arc-minute resolution. GEOID18 is used to convert the ellipsoidal height acquired by the Global Positioning System (GPS) in NAD83(2011) into an NAVD 88 orthometric height - the datum used in many maps, charts, and other applications. xGEOID19B and USGG2012 are computed using gravity data and can be used for circulation studies and other applications. completed NOS NGS GEOID TEAM ngs.geoid.team@noaa.gov pointOfContact Maddock, Shawn shawn.maddock@noaa.gov custodian notPlanned Model series has been completed with no intention to provide further updates. Geodetic Control Theme NGDA National Geospatial Data Asset NGDAID50 theme NGDA Portfolio Themes DEFLEC12A DEFLEC12B DEFLEC18 EGM2008 Elevation GEOID03 GEOID12A GEOID12B GEOID18 Geodesy Geodetic/Global Positioning Gravity Fields INTERIOR AND CRUST LAND Terrain Elevation Topographic Data USGG2012 theme Alaska American Samoa Caribbean Commonwealth of the Northern Mariana Islands Guam Hawaii Mexico Puerto Rico United States Virgin Islands place DOC/NOAA/NOS/NGS > National Geodetic Survey, National Ocean Service, NOAA, U.S. Department of Commerce dataCentre Global Change Master Directory (GCMD) Data Center Keywords 2017-04-24 publication 8.5 Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA) https://forum.earthdata.nasa.gov/app.php/tag/GCMD%2BKeywords GCMD Keyword Forum Page Global Change Master Directory (GCMD). 2025. GCMD Keywords, Version 22. Greenbelt, MD: Earth Science Data and Information System, Earth Science Projects Division, Goddard Space Flight Center (GSFC), National Aeronautics and Space Administration (NASA). URL (GCMD Keyword Forum Page): https://forum.earthdata.nasa.gov/app.php/tag/GCMD+Keywords information custodian NGS Metadata Library project InPort otherRestrictions Cite As: National Geodetic Survey, [Date of Access]: Geoid Height and Deflections of the Vertical Models [Data Date Range], https://www.fisheries.noaa.gov/inport/item/39739. NOAA provides no warranty, nor accepts any liability occurring from any incomplete, incorrect, or misleading data, or from any incorrect, incomplete, or misleading use of the data. It is the responsibility of the user to determine whether or not the data is suitable for the intended purpose. otherRestrictions Access Constraints: None otherRestrictions Use Constraints: Data in the NGS Integrated Database (IDB) are constantly updated, hence older hybrid geoid models are not consistent with newer ellipsoid and orthometric heights present in the IDB today. To obtain the most consistency between GPS derived ellipsoid heights and NAVD 88, the latest hybrid geoid model valid for that region should be used, either GEOID18 or GEOID12B. While the hybrid geoid model(s) extends into Canada, Mexico, Bermuda, the Bahamas, and into large water bodies like the Great Lakes and ocean, these model(s) have no real value in those places and should not be used in those areas. The reason for this is that significant extrapolation errors can be present and expected in areas where there are no GPS on bench mark data to constrain the model. otherRestrictions Distribution Liability: Data in the NGS Integrated Database (IDB) are constantly updated, hence older hybrid geoid models are not consistent with newer ellipsoid and orthometric heights present in the IDB today. To obtain the most consistency between GPS derived ellipsoid heights and NAVD 88, the latest hybrid geoid model valid for that region should be used, either GEOID18 or GEOID12B. While the hybrid geoid model(s) extends into Canada, Mexico, Bermuda, the Bahamas, and into large water bodies like the Great Lakes and ocean, these model(s) have no real value in those places and should not be used in those areas. The reason for this is that significant extrapolation errors can be present and expected in areas where there are no GPS on bench mark data to constrain the model. unclassified NOAA Data Management Plan (DMP) NOAA/NMFS/EDM 39739 https://www.fisheries.noaa.gov/inportserve/waf/noaa/nos/ngs/dmp/pdf/39739.pdf WWW:LINK-1.0-http--link NOAA Data Management Plan (DMP) NOAA Data Management Plan for this record on InPort. information crossReference eng; US location -130 -60 24 58 Conterminous United States -69 -64 15 21 Puerto Rico and U.S. Virgin Islands 172 -126 49 72 Alaska -161 -154 18 24 Hawaii -174 -168 -17 -11 American Samoa 143 146 11 18 Guam and Northern Mariana Islands | Currentness: Publication Date 2012 xGEOID19B (or USGG2012) are gravimetric models that refer to the Geodetic Reference System 1980 (GRS80) while the hybrid model GEOID18 (or GEOID12B) is fixed to the GPS/leveling data at bench marks of the North America Vertical Datum 1988 (NAVD 88) - the official US height system. Therefore, GEOID18 (or GEOID12B) converts the ellipsoidal height of GPS into the official NAVD 88 orthometric height. More specifically, GEOID18 converts the ellipsoidal height in the North American Datum of 1983 (NAD83(2011)) into orthometric height in NAVD 88 for the conterminous United States and GEOID12B does the same for Alaska. Each region where NAVD 88 does not exist is a bit unique. For Puerto Rico and the US Virgin Islands, GEOID18 converts the ellipsoidal height in NAD83(2011) into orthometric heights in the Puerto Rico Vertical Datum of 2002 (PRVD02) and the Virgin Islands Vertical Datum of 2009 (VIVD09), respectively. For Hawaii, GEOID12B converts the ellipsoidal height in NAD83(PA11) into the local vertical datum. For Guam and the Commonwealth of the Northern Mariana Islands, GEOID12B is used to convert the ellipsoidal height in NAD83(MA11) into the orthometric height in the Guam Vertical Datum of 2004 (GUVD04) and the Northern Marianas Vertical Datum of 2003 (NMVD03), respectively. DEFLEC18 (or DEFLEC12B) is a model of deflection of the vertical that describes the angular difference between the norm of the zero-height-surfaces and the norm of the reference ellipsoid. These deflection models are computed from their corresponding geoid model and provided in two principal component grids: North-South and East-West. All grids are provided at 1 arc-minute resolutions. NGS offers technical information of the geoid models and practical information concerning its use at the following: https://geodesy.noaa.gov/GEOID. NGS also offers a variety of support and training on the use of these models and datums at the following: https://geodesy.noaa.gov/corbin/index.shtml. Notice that Hawaii, Guam, CNMI, American Samoa, Puerto Rico (PR), and the U.S. Virgin Islands (VI) all have their own separate vertical datums distinct from NAVD 88. GEOID18 (or GEOID12B) converts between the appropriate local version of NAD 83 and the respective vertical datums for each of these regions. The GEOID18 (or GEOID12B) product comprises eight files for the conterminous United States: four files for Alaska, and one each for Hawaii, PR/VI, American Samoa, and Guam/CNMI. Single grids also are available for CONUS and Alaska. Each file contains geoid heights on a one-minute by one-minute grid in both big-endian and little-endian binary (PC compatible) formats. The INTG program is supplied at the download site to interpolate to a specific position within these grids. Another program, XNTG, is supplied to extract subsets and convert the grids between ASCII and binary. Both are in FORTRAN, are available compiled and as source code, and can byte-swap the grids if needed on a Unix platform. There is also an on-line geoid computational facility within the NGS Geodetic Tool Kit at https://geodesy.noaa.gov/TOOLS. Similar files, programs, and on-line computational facilities exist for GEOID18, GEOID12B, DEFLEC18, and DEFLEC12B. programs for PC or UNIX Text (Structured) NGS Communications and Outreach Branch (301) 713-3242 (301) 713-4172 ngs.infocenter@noaa.gov distributor https://geodesy.noaa.gov/GEOID/ WWW:LINK-1.0-http--link NGS GEOID Homepage Geoid model landing page can be used to access various models, datasets, software, applications, and additional documentation. download https://geodesy.noaa.gov/web_services/geoid.shtml WWW:LINK-1.0-http--link API for NGS GEOID Landing page for GEOID API that allows interpolation of various geoid models at user provided geographic locations. download