Which datum is based on the GRS80 ellipsoid?

The North American Datum of 1983 (NAD83) is based on the Geodetic Reference System 1980 (GRS80) ellipsoid. This ellipsoid serves as a mathematical model of the Earth's shape and is used as a reference frame for geographic coordinates. NAD83 was developed to provide a more accurate representation of the Earth's surface than its predecessor, NAD27, which is based on a different ellipsoid (the Clarke 1866 ellipsoid).

The use of the GRS80 ellipsoid in NAD83 allows for better alignment with modern satellite data and Global Positioning Systems (GPS). This alignment is crucial for applications that require precise location measurements, such as surveying, mapping, and navigation in a rapidly changing world.

While World Geodetic System 1984 (WGS84) is also associated with the GRS80 ellipsoid, it is primarily used for global positioning systems and has different applications and adjustments for global use compared to NAD83, which is regional.

UTM, or Universal Transverse Mercator, is a map projection system that divides the world into a series of zones but does not refer to a specific datum itself.

Understanding these distinctions is vital for those working in GIS, as using the correct datum ensures