The routine accuracy assessment of Sentinel-3 is carried out by comparing the generated orbital products by the Copernicus POD Service against external orbits provided by ESOC, generated from independent observation RINEX [ftp://igscb.jpl.nasa.gov/pub/station/general/antex14.txt] directly decoded from the GPS L0 files, and against CNES orbital products based both on DORIS and GPS processing.
In the case of the attitude files, the Precise Platform Data Files are compared against the theoretical attitude law to verify that it is being followed to the mission requirements.
Since there is no other external source of attitude against which to compare the generated platform data files, no further validation is available.
The following figures show that the accuracy requirements are regularly met. The cases in which they are not are usually related to manoeuvres or GPS data outages.
Further comparisons against the rest of the external validation centres which belong to the POD Quality Working Group are carried out every four months for the Regular Service Review. As a summary of the latest one, the following comparisons are available for the NTC product: