WGS84 vs ETRS89

Mapping out the Earth can be a very comprehensive, long, drawn-out task. The fact of the matter is, it is a very underappreciated but extremely important body of information. Many applications involving navigation and topographical data would be non-existent without such information. Modern technology has facilitated the development and maintenance of established mapping parameters. Two of the most significant developments in the last couple of decades are the establishment of WGS84 and ETRS89.

WGS84 refers to the most recent revision of the World Geodetic System (WGS). The number represents the date when this iteration originated (which was in 1984, though revisions were made in 2004 at the latest). Though this was deemed valid only until 2010, no new updates have been provided. Previous iterations of the World Geodetic System were WGS60, 66, and 72 (all representing the years they were established).

The World Geodetic System is the standard used when it comes to cartography and navigation as well as geodesy (i.e., a branch of Earth Sciences that deal with measuring and accurately representing the Earth). This system sets the parameters for which certain measurements are made in determining the reference points on the planet based on the establishment of a standard coordinate frame for the Earth and other details (such as the datum and the geoid). WGS84 uses the GRS80 ellipsoid as the basis for its parameters. But why is this information important to common folk who have no interest or more specialized knowledge in geodesy and Earth Sciences? The importance stems from the fact that WGS84 is the system used by the Global Positioning System (GPS).

The revision in 1984 was brought about by the recognition that a new World Geodetic System was needed at the urging of different parties, such as geodetic experts in the scientific community as well as the United States’ Department of Defense. By these parties’ reckoning, the previously established WGS72 was obsolete, providing inadequate and insufficient data for the current (at that time) and future applications. Through an array of techniques and resources, notably the use of state-of-the-art satellite technology, new and more dynamic data and information was collated to form the basis of WGS84. The new system produced a baseline that is geocentric and consistent, accurate up to plus or minus one meter. As mentioned before, WGS84 continues to be refined as new information and technology is developed.

At the other end, the European Terrestrial Reference System 1989 (ETRS89) is an Earth-Centered Earth-Fixed (ECEF) geodetic Cartesian reference frame utilized primarily for the European areas (whereas WGS84 is global). This is the basis by which the coordinates of maps and locations in Europe are derived from. Within its parameters, it treats the Eurasian Plate as a static, non-changing constant; thus, the continental drift is not factored in on maps based on ETRS89. This system was established and officially accepted in the year 1990. This occurred in the Florence meeting of the EUREF (Regional Reference Frame Sub-Commission for Europe). ETRS89 was developed with the International Terrestrial Reference System (ITRS) geodetic datum being taken into consideration. EUREF’s Resolution 1 led to its development as a means of adopting the ITRS using the constantly stable section of the Eurasian plate. Because of this, the ETRS89 and ITRS have very little divergence and disparity. Unlike WGS84, the numerical part of ETRS89 is not based on what year the system was established but rather when it was completely in sync with the ITRS. To reflect this, solutions produced through using ETRS89 have comparative ITRS solutions. ETRS89 is constantly monitored and updated by the EUREF through its Permanent Network (EPN).

While there are certainly similarities between the two, the scope covered by WGS84 is much wider. However, it can certainly be useful to know how ETRS89 works should one ever be in the European territories.

Summary:

1.WGS84 is the World Geodetic System or, more specifically, the most recent revision based on the version established in 1984.
2.European Terrestrial Reference System 1989 (ETRS89) is the geodetic reference frame utilized for the European areas.
3.WGS84’s scope is worldwide while ETRS89 is limited to the European/Eurasian areas.
4.Whereas WGS84’s numerical element is based on the year this version of the system was established, ETRS89’s is based on when it was 100 per cent equivalent to the International Terrestrial Reference System (ITRS).

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