CoAuthors

Laure MICHAUD (CLS, France); François BIGNALET-CAZALET (CNES, France); Nicolas PICOT (CNES, France)

Jason-2 is the reference mission on TOPEX/Poseidon historical ground track for mean sea level applications from 2008 et 2016. It is also used to observe mesoscale ocean dynamics. Over the last 3 years many events occurred on Jason-2 mission. As for Jason-1 and TOPEX/Poseidon before it, Jason-2 was first moved to an interleaved but at the same altitude orbit in October 2016. Due to several gyro anomalies, system Safe Hold Modes (SHM) occurred and Jason-2 was moved to a Long Repeat Orbit (LRO) in July 2017. This orbit is approximately 27 km below the previous orbit still used by Jason-3. Thanks to this first year flying over Long Repeat Orbit, along-track data are available following an 8km resolution grid. During this period SHM occurred twice (in September 2017 and February 2018). Since its move in July 2018 to an interleaved LRO (i-LRO) SHMs have again occurred by four times (in oct-18, dec-18 and twice in feb-19). In addition to data from first year on LRO, this i-LRO will allow to provide data on a 4km resolution grid thanks to a complete second year of measurements, which is of great interest for geodesic community. It was so decided to enter a hibernation phase for about 3 months, and to develop and then apply a strategy to switch between operational and healthy gyros, in order to reduce the SHM events risk.
Since 22nd May 2019, Jason-2 has been re-operating, and has provided telemetry measurements. Data are analyzed and monitored in order to assess the quality of the products and how the system performance and data quality are affected (or not) by these events. The objective of this presentation consists in giving an overview of Jason-2 data coverage and data quality concerning altimeter and radiometer parameters, but also the performance of products at mono-mission crossovers and along-track.