The Jason-CS/Sentinel-6 Ocean Surface Topography Mission

Craig Donlon, European Space Agency, ESTEC, Villanueva De La Can, Spain, Robert Cullen, European Space Research and Technology Centre, Earth Observation Project Department, Noordwijk, Netherlands and Remko Scharroo, EUMETSAT, Darmstadt, Germany
Abstract:
The Jason-CS/Sentinel-6 (JCS/S6) mission will consist of 2 spacecraft providing the latest in a series of ocean surface topography “reference” satellite altimeters on-board TOPEX/Posiedon through to Jason-3 that span nearly 3 decades. It is a part of the European Copernicus Programme to establish a capacity for Earth Observation and associated services. It will continue to fulfil reference altimeter series objectives but will also introduce a major enhancement in capability to the operational and scientific oceanographic community. The 1st satellite is planned for launch in 2020 with the 2nd satellite 5 years later. Partner Agencies include ESA, EUMETSAT, NASA, EU and CNES. The mission design is based on a platform derived from CryoSat-2 but adjusted to the specific requirements of the higher reference mission orbit. Building on the heritage of previous ESA instruments (SIRAL and SRAL), the principle payload instrument is a high precision dual-frequency (for high stability ionospheric path delay correction) Ku/C band synthetic aperture radar altimeter (POSIEDON-4). Retrieval of geophysical parameters (surface elevation, wind speed and SWH) from the altimeter data uses measurements from a DORIS receiver (for Precise Orbit Determination (POD)) and the Climate Quality Advanced Microwave Radiometer (AMR-C) provided by JPL (for high stability wet-tropospheric path delay correction). Orbit tracking data are derived from a GPS and a Laser Retro Reflector. A 2nd GNSS-RO will be flown that is dedicated to radio-occultation measurements. The JCS/S6 altimeter will be the 1st Synthetic Aperture Radar (SAR) altimeter used as part of the reference altimeter mission series. It will also be the 1st altimeter to operate in a continuous high-rate pulse mode optimizing the RADAR sampling strategy and allowing, for the first time simultaneous production of low-resolution mode measurements on-board as well as the processing of SAR echoes on-ground. Both types of measurements will be provided in separate data products that must be managed to continue the reference altimeter series.