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International Terrestrial Reference System and Frame

World spatial reference system co-rotating with the Earth in its diurnal motion in space

Summary

World spatial reference system co-rotating with the Earth in its diurnal motion in space

The International Terrestrial Reference System (ITRS) describes procedures for creating reference frames suitable for use with measurements on or near the Earth's surface. This is done in much the same way that a physical standard might be described as a set of procedures for creating a realization of that standard. The ITRS defines a geocentric system of coordinates using the SI system of measurement.

An International Terrestrial Reference Frame (ITRF) is a realization of the ITRS. Its origin is at the center of mass of the whole earth including the oceans and atmosphere. New ITRF solutions are produced every few years, using the latest mathematical and surveying techniques to attempt to realize the ITRS as precisely as possible. Due to experimental error, any given ITRF will differ very slightly from any other realization of the ITRF. The difference between the latest as of 2006 WGS 84 (frame realisation G1150) and the latest ITRF2000 is only a few centimeters and RMS difference of one centimeter per component. ITRFs are Earth-centered, Earth-fixed (ECEF) reference frames.

The ITRS and ITRF solutions are maintained by the International Earth Rotation and Reference Systems Service (IERS). Practical navigation systems are in general referenced to a specific ITRF solution, or to their own coordinate systems which are then referenced to an ITRF solution. For example, the Galileo Terrestrial Reference Frame (GTRF) is used for the Galileo navigation system; currently defined as ITRF2005 by the European Space Agency.

Versions

The ITRF realizations developed from the ITRS since 1991 include the following versions:

Name	Ref.	EPSG
code	Notes	ITRF91	ITRF92	ITRF93	ITRF94	ITRF96	ITRF97	ITRF2000	ITRF2005	ITRF2008	ITRF2014	ITRF2020
1988.0	4913
1988.0	4914	First realization of the ITRS
1988.0	4915
1993.0	4916
1997.0	4917
1997.0	4918
1997.0	4919	First solution that combines unconstrained space geodesy solutions free from any tectonic plate motion model.
2000.0	4896	last1=Altamimi	first1=Z.	last2=Collilieux	first2=X.	last3=Legrand	first3=J.	last4=Garayt	first4=B.	last5=Boucher	first5=C.	title=ITRF2005: A new release of the International Terrestrial Reference Frame based on time series of station positions and Earth Orientation Parameters	journal=Journal of Geophysical Research: Solid Earth	volume=112	pages=B09401	number=B9	doi=10.1029/2007JB004949	year=2007	bibcode=2007JGRB..112.9401A	hdl=10338.dmlcz/141752	hdl-access=free }}
2005.0	5332	last1=Altamimi	first1=Zuheir	last2=Collilieux	first2=Xavier	last3=Métivier	first3=Laurent	title=ITRF2008: an improved solution of the international terrestrial reference frame	journal=Journal of Geodesy	date=3 February 2011	volume=85	issue=8	pages=457–473	doi=10.1007/s00190-011-0444-4	bibcode=2011JGeod..85..457A	doi-access=free}}
2010.0	7789	Generated with an enhanced modeling of nonlinear station motions. Specifically:
2015.0	9988

Users

GNSS systems:

Galileo Terrestrial Reference Frame (GTRF), ITRF2005; own implementation using IGS sites.
GPS just uses WGS 84, ITRF2020 since January 2024 (but used many versions of WGS 84 before), a little modified with International GNSS Service (IGS) implementation, IGS20.
BeiDou Coordinate System, China Terrestrial Reference Frame (CTRF) 2000 = ITRF97 at epoch 2000.0; own implementation.
GLONASS PZ-90.11 is nominally its own system, but is quite close to ITRF and uses many of the same techniques.

National systems:

United States: WGS 84 (see above); domestic use is mainly based on NAD 83 instead.
China: CTRF 2000 per above.

The GPS reference epoch was moved from 2000.0 to 2001.0 in G1150 due to the magnitude 7.9 Denali Fault earthquake in Alaska in November 2002. Still in 2022 ITRF2020 was released, yet GPS was only using G2139 in its antennas, which was aligned to ITRF2014 (IGb14) (though at epoch 2016.0, not reference epoch 2010.0). On 7 January 2024 move to IGS20 happened, so WGS 84 is now aligned with ITRF2020, including PSD (post-seismic deformation), also called G2296.

On the other hand GLONASS is using PZ-90.11, which is close to ITRF2008 at epoch 2011.0 and is using 2010.0 epoch (that means when you use reference transformation to PZ-90.11 you will get January 2010 date).

References

Clynch, James R.. (February 2006). "Earth coordinates". James R. Clynch.
"Reference Frames in GNSS". European Space Agency.
(February 2023). "International Terrestrial Reference Frame 2014 (ITRF2014)".
(2007). "ITRF2005: A new release of the International Terrestrial Reference Frame based on time series of station positions and Earth Orientation Parameters". Journal of Geophysical Research: Solid Earth.
(3 February 2011). "ITRF2008: an improved solution of the international terrestrial reference frame". Journal of Geodesy.
(2016). "ITRF2014: A new release of the International Terrestrial Reference Frame modeling nonlinear station motions". Journal of Geophysical Research: Solid Earth.
"ITRF {{!}} Itrf2020".
"Transitioning from IGS14 to IGb14 - National Geodetic Survey".

Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

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