The North American Datum is the official reference ellipsoid used for the primary geodetic network in North America. Currently, in the fields of cartography and land-use; there are two North American Datums in use: North American Datum of 1927 (NAD 27) and North American Datum of 1983 (NAD 83). Both are geodetic reference systems, but each is based on different measurements. This article or section should include material from Erdmessung. ...

North American Datum of 1927

The North American Datum of 1927 (NAD27) is a datum based on the Clarke Ellipsoid of 1866. This Ellipsoid was created by way of manual surveying of the entire continent. The geodetic "center" of NAD-27 is a base station at Meades Ranch in Kansas. It has been suggested that this article or section be merged with Geodetic system. ... Meades Ranch in Kansas boasts the geodetic base point for the North American Datum of 1927 (NAD 27) at 39° 13 26. ...

North American Datum of 1983

As satellite and remote sensing technology both improved and were made available for civilian applications, it became obvious that the NAD-27's appromixations were not sufficiently accurate. An Earth observation satellite, ERS 2 For other uses, see Satellite (disambiguation). ... Synthetic aperture radar image of Death Valley colored using polarimetry In the broadest sense, remote sensing is the measurement or acquisition of information of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object. ... In times of armed conflict a civilian is any person who is not a combatant. ...

The North American Datum of 1983 was created to meet requirements for better accuracy and more precision. It is based on the GRS80 ellipsoid; an ellipsoid derived from satellite geodesy. Definition GRS 80, or Geodetic Reference System 1980, is a geodetic reference system consisting of a global reference ellipsoid and a gravity field model. ... An Earth observation satellite, ERS 2 For other uses, see Satellite (disambiguation). ... It has been suggested that geodetic system be merged into this article or section. ...

Comparisons Between NAD-27 and NAD-83

A point having a given latitude and longitude in NAD27 may be displaced on the order of many tens of meters from another point having the identical latitude and longitude in NAD83. So it is important to specify the datum along with the coordinates. The North American Datum of 1927 is defined by the latitude and longitude of an initial point (Meades Ranch in Kansas), the direction of a line between this point and a specified second point, and two dimensions that define the spheroid. The North American Datum of 1983 is based on a newer defined spheroid (GRS80); it is an Earth-centered datum having no initial point or initial direction. Meades Ranch in Kansas boasts the geodetic base point for the North American Datum of 1927 (NAD 27) at 39° 13 26. ... In mathematics, a spheroid is a quadric surface in three dimensions obtained by rotating an ellipse about one of its principal axes. ...

External links

• NADCON – a free utility to convert between NAD27 and NAD83
  • nadcon.prl – a web-based utility for NADCON

See also

• WGS-84