Related Projects and Programs

Ongoing projects and programs

Research Geoids

The experimental geoid models allow users to see improvements gained by the addition of new data from our Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project. The experimental geoid models also provide the latest approximations for the redefined vertical datum. learn more >

International Great Lakes Datum of 2020 (IGLD2020)

The IGLD2020 is under development by the Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data. This international committee is composed of US and Canadian supporting agencies, including NOAA (with participants from NGS and the Center for Operational Oceanographic Products and Services [CO-OPS]), and provides information on this IGLD update, as well as previous Great Lakes Datums IGLD55 and IGLD85. learn more >.

NOAA Foundation CORS Network (NFCN)

To support future requirements and prepare for the transition to the new datums, NGS is constructing a small number of ultra-stable Foundation CORSs (Continuously Operating Reference Stations). NGS expects to establish one to two new Foundation CORSs per year and will oversee the installation of a minimum of eight Foundation CORSs in the continental United States, with additional sites to be constructed in Alaska, Hawaii, United States territories, and select foreign countries. Collectively, these foundation CORSs will be called the NOAA Foundation CORS Network (NFCN). learn more >

Completed projects

GPS on Bench Marks

GPS on Bench Marks was an effort to collect GPS observations on marks that previously only had a historic orthometric height, based on leveling, that made up the North American Vertical Datum of 1988 (NAVD 88). These marks were part of historic geodetic leveling surveys, but they are often difficult and expensive to access. By adding GPS observations to these marks, NGS significantly increased the amount of data to be used in a planned expansion of VERTCON (a tool within the NGS Coordinate Conversion and Transformation Tool [NCAT]), which will relate current vertical datums (NAVD 88, et al.) to the North American-Pacific Geopotential Datum of 2022 (NAPGD2022) epoch 2020.00. learn more >.

Geoid Slope Validation Surveys (GSVSs)

Geoid Slope Validation Surveys have demonstrated the accuracy of differential geoid undulations between points (“geoid slopes”) for NGS’s gravimetric geoid models, and explicitly showed the improvement in accuracy by adding data from NGS’s GRAV-D airborne gravity campaign. Independently computed geoid slopes were used as a baseline for comparison using two methods: (1) Differential orthometric heights and differential ellipsoid heights from leveling and GPS campaigns, respectively; and (2) Astro-geodetic deflections of the vertical from observations using the Swiss DIADEM camera. learn more >

Gravity for the Redefinition of the American Vertical Datum (GRAV-D)

GRAV-D was an NGS ambitious enterprise to re-define the vertical datum of the United States through a two-stage process. In the first stage of the project, NGS collected a high-resolution “snapshot” of gravity in the United States by acquiring new airborne gravity data. In the second stage (ongoing), NGS is monitoring geoid change primarily through the use of ongoing satellite gravity missions. learn more >

New Datums

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