North American Datum of 1983

摘要

The North American Datum of 1983 (NAD 83) is the third horizontal geodetic datum of continental extent in North America. It is intended to replace both the original North American Datum and the North American Datum of 1927 (NAD 27) for all purposes. The fundamental task of NAD 83 was a simultaneous least squares adjustment involving 1,785,772 observations and 266,436 stations in the United States, Canada, Mexico, and Central America. Greenland, Hawaii, and the Caribbean islands were connected to the datum through Doppler satellite and Very Long Baseline Interferometry (VLBI) observations. The computations were performed with respect to the ellipsoid of the Geodetic Reference System of 1980 (GRS 80), recommended by the International Association of Geodesy (IAG). The report covers the background of the project. It also describes the actual execution, including the inventory of data used, the long laborious task of building the data base, the computations themselves, and the datum implementation activities. It does not include the actual coordinates, which must be ordered from the National Geodetic Information Branch, NOAA.