Sentinel 6/Jason-CS Poseidon 4 L1 Ground Processor Prototype (GPP) is an operational oceanography programme of two satellites that ensures continuity to the Jason series of operational missions.
The main payload of the Jason-CS satellite is the Poseidon-4 radar altimeter that has evolved from the altimeters on-board the Jason satellites (Poseidon-2 of Jason-1, Poseidon-3A of Jason-2 and Poseidon-3B of Jason-3). Poseidon-4 also inherits the Synthetic Aperture Radar (SAR) Altimeter mode of CryoSat-2 SIRAL and Sentinel-3 SRAL proven to reduce errors in elevation and SWH retrieval over ocean. Furthermore, Poseidon-4 will be the first radar altimeter embarked on a satellite that includes improved digital and radio frequency hardware and, in particular, open burst Ku-band pulse transmission (an operation currently termed the interleaved mode), that performs a near continuous transmission of Ku-band pulses, that will allow SAR and pulse limited data to be gathered simultaneously. As with the Jason series and Sentinel-3, the Poseidon-4 transmits C-band pulses in order to retrieve a correction for ionospheric path delay. The prototype was verified using simulated data generated by the Sentinel 6/Jason-CS mission performance simulator and also using in-orbit CryoSat-2 data adapted in format to Jason-CS.
The mission was developed by a multi Agency partnership consisting of ESA, EUMETSAT, NASA-JPL, and NOAA. ESA is responsible for the Jason-CS Space Segment development along with Astrium GmbH as a prime contractor.
isardSAT developed the Ground Prototype Processor for the Poseidon-4. This prototype processes all the chains starting from the Instrument Source Packets, and up to the Level 1B (calibrated pulse-width limited or multi-looked SAR data). The prototype has been verified using simulated data generated by the Sentinel 6/Jason-CS mission performance simulator and also using in-orbit CryoSat-2 data adapted in format to Jason-CS. isardSAT has been involved since phase A and will participate until end of Sentinel-6 commissioning. isardSAT is now in charge of the L1 GPP update and internal & external calibration.