CoAuthors

Cristina Martin-Puig (EUMETSAT, Germany); Marco Meloni (EUMETSAT, Germany); Carolina Nogueira Loddo (EUMETSAT, Germany); Mike Grant (EUMETSAT, Germany); Bruno Lucas (EUMETSAT, Germany); Hendrik Merx (HE Space for EUMETSAT, Germany)

Since the launch of Sentinel-6 Michael Freilich on 21 November 2020, the products coming from the operational ground segment have been carefully monitored to ensure the best performance. Although the ground segment was more ready for purpose than could have been expected during the pandemic, it was of course expected that some anomalies would occur in a brand new ground segment. Anomalies, biases, and misconfigurations were efficiently dealt with, although this quite often hampered the consistency of the products. This was expected, and EUMETSAT took care to inform the early users --- members of the Sentinel-6 Validation Team (S6VT) --- of any changes affecting the products, also letting them in to outputs of the validation platform where changes were first introduced.

The commissioning phase was set up in various stages, first focussing on the low-resolution (LR) near-realtime (NRT) and short-time critical (STC) products, and then later expanding to the high-resolution (HR) and non time critical (NTC) products. Through several meetings with the S6VT, recommendations were made to stagger the release of the data to the general public, noting their compliance to the performance requirements with some caveats.

Meanwhile, a switch from the nominal (Side A) to the redundant (Side B) of the altimeter was also planned and executed. This build in an actual full redundancy, knowing that Side A have been fully characterised and cross-calibrated, so at it stands ready to be reverted to in case of failure or severe degradation of the now operational Side B.

At the end of the commissioning data from the entire mission was reprocessed with the then operational processors and configuration so that a consistent data set was obtained, further allowing a thorough cross-calibration and providing all the data to all users, including during the earlier commissioning period.

But the status of the processors is not frozen, as the state of the art is continuously evolving, and for the best performance of the mission, the processors need to go with it. This includes changes that already became operational since late September:
- Addition of the 3 high-frequency HRMR channels in the computation of the wet tropospheric correction, improving coastal retrievals
- Use of the around-the-orbit ECHO Cal for the calibration of range and power, reducing the influence of temperature variations on retrievals

This presentation summarises the status of the data processing and reprocessing activities.