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The National Geodetic Survey (NGS) is a
United States federal agency that defines and manages a national coordinate system, providing the foundation for transportation and communication; mapping and charting; and a large number of applications of science and engineering. Since its foundation in its present form in 1970, it has been part of the
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...
(NOAA), of the
United States Department of Commerce
The United States Department of Commerce is an executive department of the U.S. federal government concerned with creating the conditions for economic growth and opportunity. Among its tasks are gathering economic and demographic data for bu ...
.
History
The National Geodetic Surveys history and heritage are intertwined with those of other NOAA offices. It traces its history to the Survey of the Coast, which was formed in 1807 as the first scientific agency of the
United States Government
The federal government of the United States (U.S. federal government or U.S. government) is the national government of the United States, a federal republic located primarily in North America, composed of 50 states, a city within a fede ...
. It became the United States Coast Survey in 1836 and the United States Coast and Geodetic Survey in 1878, the latter name change reflecting the increasing role of
geodesy
Geodesy ( ) is the Earth science of accurately measuring and understanding Earth's figure (geometric shape and size), orientation in space, and gravity. The field also incorporates studies of how these properties change over time and equivale ...
in its work. Upon the creation of NOAA in 1970, the Coast and Geodetic Survey was abolished and its responsibilities were split among various agencies and offices of NOAA. The Coast and Geodetic Survey′s former geodetic responsibilities were placed under the new National Geodetic Survey in NOAA's National Ocean Survey (later renamed the
National Ocean Service
The National Ocean Service (NOS) is an office within the U.S. Department of Commerce National Oceanic and Atmospheric Administration (NOAA). It is responsible for preserving and enhancing the nation's coastal resources and ecosystems along the of ...
).
In 2009, former
officer
An officer is a person who has a position of authority in a hierarchical organization. The term derives from Old French ''oficier'' "officer, official" (early 14c., Modern French ''officier''), from Medieval Latin ''officiarius'' "an officer," f ...
Juliana P. Blackwell was named Director of the National Geodetic Survey, becoming the first woman to head either NGS or any of its ancestor organizations.
Purpose and function
The National Geodetic Survey is an office of NOAA's
National Ocean Service
The National Ocean Service (NOS) is an office within the U.S. Department of Commerce National Oceanic and Atmospheric Administration (NOAA). It is responsible for preserving and enhancing the nation's coastal resources and ecosystems along the of ...
. Its core function is to maintain the
National Spatial Reference System
The National Spatial Reference System (NSRS), managed by the National Geodetic Survey (NGS), is a coordinate system that includes latitude, longitude, elevation, and other values. The NSRS consists of a National Shoreline, the NOAA CORS Network (a ...
(NSRS), "a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States". NGS is responsible for defining the NSRS and its relationship with the
International Terrestrial Reference Frame (ITRF). The NSRS enables precise and accessible knowledge of where things are in the United States and its territories.
The NSRS may be divided into its geometric and physical components. The official geodetic datum of the United States,
NAD83
The North American Datum (NAD) is the horizontal datum now used to define the geodetic network in North America. A datum is a formal description of the shape of the Earth along with an "anchor" point for the coordinate system. In surveying, ...
defines the geometric relationship between points within the United States in three-dimensional space. The datum may be accessed via NGS's network of survey marks or through the
Continuously Operating Reference Station
Real-time kinematic positioning (RTK) is the application of surveying to correct for common errors in current satellite navigation (GNSS) systems. It uses measurements of the phase of the signal's carrier wave in addition to the information cont ...
(CORS) network of
GPS
The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
reference antennas. NGS is responsible for computing the relationship between NAD83 and the ITRF. The physical components of the NSRS are reflected in its height system, defined by the vertical datum
NAVD88
The North American Vertical Datum of 1988 (NAVD 88) is the vertical datum for orthometric heights established for vertical control surveying in the United States of America based upon the General Adjustment of the North American Datum of 1988.
...
. This datum is a network of
orthometric height
The orthometric height is the vertical distance ''H'' along the plumb line from a point of interest to a reference surface known as the ''geoid'', the vertical datum that approximates mean sea level. Orthometric height is one of the scientific fo ...
s obtained through spirit
leveling
Levelling or leveling (American English; see spelling differences) is a branch of surveying, the object of which is to establish or verify or measure the height of specified points relative to a datum. It is widely used in geodesy and cartogra ...
. Because of the close relationship between height and Earth's gravity field, NGS also collects and curates terrestrial
gravity
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
measurements and develops regional models of the
geoid
The geoid () is the shape that the ocean surface would take under the influence of the gravity of Earth, including gravitational attraction and Earth's rotation, if other influences such as winds and tides were absent. This surface is extended ...
(the level surface that best approximates sea level) and its slope, the
deflection of the vertical
The vertical deflection (VD) or deflection of the vertical (DoV), also known as deflection of the plumb line and astro-geodetic deflection, is a measure of how far the gravity direction at a given point of interest is rotated by local mass anoma ...
. NGS is responsible for ensuring the accuracy of the NSRS over time, even as the
North American plate
The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...
rotates and deforms over time due to crustal strain,
post-glacial rebound
Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound a ...
,
subsidence
Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope move ...
, elastic deformation of the crust, and other geophysical phenomena.
NGS will release new datums in 2022. The North American Terrestrial Reference Frame of 2022 (NATRF2022) will supersede NAD83 in defining the geometric relationship between the North American plate and the ITRF.
United States territories on the Pacific, Caribbean, and Mariana plates will have their own respective geodetic datums. The North American-Pacific Geopotential Datum of 2022 (NAPGD2022) will separately define the height system of the United States and its territories, replacing NAVD88.
It will use a geoid model accurate to 1 centimeter (0.4") to relate orthometric height to ellipsoidal height measured by GPS, eliminating the need for future leveling projects. This geoid model will be based on airborne and terrestrial gravity measurements collected by NGS's GRAV-D program as well as satellite-based gravity models derived from observations collected by
GRACE
Grace may refer to:
Places United States
* Grace, Idaho, a city
* Grace (CTA station), Chicago Transit Authority's Howard Line, Illinois
* Little Goose Creek (Kentucky), location of Grace post office
* Grace, Carroll County, Missouri, an uninco ...
,
GOCE
''Goce'' is an opera composed by Kiril Makedonski (1925–1984), written by Venko Markovski and dedicated to Gotse Delchev. The work was commissioned to be the very first opera performed by the Macedonian National Opera Company. It premiered o ...
, and
satellite altimetry
Satellite geodesy is geodesy by means of artificial satellites—the measurement of the form and dimensions of Earth, the location of objects on its surface and the figure of the Earth's gravity field by means of artificial satellite technique ...
missions.
NGS provides a number of other public services.
It maps changing shorelines in the United States and provides aerial imagery of regions affected by natural disasters, enabling rapid damage assessment by emergency managers and members of the public. The Online Positioning and User Service (OPUS) processes user-input GPS data and outputs position solutions within the NSRS. The agency offers other tools for conversion between datums.
See also
*
Height Modernization
Height Modernization is the name of a series of state-by-state programs recently begun by the United States' National Geodetic Survey, a division of the National Oceanic and Atmospheric Administration. The goal of each state program is to place GPS ...
*
Herbert Grove Dorsey
Herbert Grove Dorsey (April 24, 1876 – 1961) was an American engineer, inventor and physicist. He was principal engineer of the United States Coast and Geodetic Survey Radiosonic Laboratory in the 1930s. He invented the first practical fathom ...
*
Surveying
Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. A land surveying professional is ca ...
*
Topography
Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps.
Topography is a field of geoscience and planetary sci ...
References
External links
National Geodetic Survey website* 1858 map
''Preliminary chart of entrance to Brazos River''hosted by the Portal to Texas History
* 1853 map
''Preliminary chart of San Luis Pass, Texas''hosted by the Portal to Texas History.
* 1854 map
''Preliminary survey of the entrance to the Rio Grande, Texas''hosted by the Portal to Texas History.
{{Authority control
Geodesy organizations
Geographic data and information organizations in the United States
National Geodetic Survey
The National Geodetic Survey (NGS) is a List of federal agencies in the United States, United States federal agency that defines and manages a national coordinate system, providing the foundation for transportation and communication; mapping an ...
Government agencies established in 1970
Exploration of North America