The Copernicus Precise Orbit Determination (CPOD) Service is pleased to announce the application of the ITRF2020 Seasonal Geocenter Motion model on our NRT, STC and NTC products for the Sentinel-1, Sentinel-2, Sentinel-3 and Sentinel-6 families.
Geocentre motion describes the variation of the Center of Mass with respect to the Center of Network. The Center of Mass, or geocenter, is understood as the center of the total Earth system or geocenter, while the Center of Network represents the realisation of the International Terrestrial Reference Frame (ITRF) using a limited number of stations (more details in the Geocenter motion in operational products Technical Note that can be found in the SentiWiki page).
The geocenter motion is affected by different geophysical effects, which give place to various types of motion of different magnitudes and frequencies. Up until this moment, the CPOD Service has been applying the IERS Convention 2010 models for the definition and displacements of reference markers on the crust, plus the post-seismic deformations. These IERS Conventions define that the translation from Center of Network to Center of Mass must account for the ocean tidal mass displacements, typically called CMC. In addition to these effects, the latest ITRF realization, the ITRF2020, defines a standard model to consider geocenter seasonal variations. These seasonal (annual and semi-annual) variations are what is routinely called “ITRF2020 Seasonal Geocenter Motion (SGM) model”. For precise orbit determination, using ITRF2020 coordinates augmented with seasonal geocenter signals improves the CoM realization and ensures a more accurate geocentric positioning.
This change has been recommended and endorsed by the CPOD QWG to align with the latest standards of LEO POD and validated by both ESA and EUMETSAT. It has been implemented in the CPOD system starting with version 3.11.x on 04/03/2025, then applicable to products generated from that date onward. Changes in products apply only to the file content, maintaining the same filename, format and timeliness. In terms of accuracy, the new ITRF2020 SGM introduces a variation of a few tenths of mm.
The Copernicus Precise Orbit Determination (CPOD) Service is pleased to announce the application of the ITRF2020 Seasonal Geocenter Motion model on our NRT, STC and NTC products for the Sentinel-1, Sentinel-2, Sentinel-3 and Sentinel-6 families.
Geocentre motion describes the variation of the Center of Mass with respect to the Center of Network. The Center of Mass, or geocenter, is understood as the center of the total Earth system or geocenter, while the Center of Network represents the realisation of the International Terrestrial Reference Frame (ITRF) using a limited number of stations (more details in the Geocenter motion in operational products Technical Note that can be found in the SentiWiki page).
The geocenter motion is affected by different geophysical effects, which give place to various types of motion of different magnitudes and frequencies. Up until this moment, the CPOD Service has been applying the IERS Convention 2010 models for the definition and displacements of reference markers on the crust, plus the post-seismic deformations. These IERS Conventions define that the translation from Center of Network to Center of Mass must account for the ocean tidal mass displacements, typically called CMC. In addition to these effects, the latest ITRF realization, the ITRF2020, defines a standard model to consider geocenter seasonal variations. These seasonal (annual and semi-annual) variations are what is routinely called “ITRF2020 Seasonal Geocenter Motion (SGM) model”. For precise orbit determination, using ITRF2020 coordinates augmented with seasonal geocenter signals improves the CoM realization and ensures a more accurate geocentric positioning.
This change has been recommended and endorsed by the CPOD QWG to align with the latest standards of LEO POD and validated by both ESA and EUMETSAT. It has been implemented in the CPOD system starting with version 3.11.x on 04/03/2025, then applicable to products generated from that date onward. Changes in products apply only to the file content, maintaining the same filename, format and timeliness. In terms of accuracy, the new ITRF2020 SGM introduces a variation of a few tenths of mm.