The Sentinel-3 Surface Topography Mission and Products
Mavrocordatos, Constantin1; Femenias, Pierre2; Picot, Nicolas3; Bonekamp, Hans4

The Sentinel-3 Surface Topography Mission (STM) is designed to monitor the surface height of the Ocean, of the ice-covered surfaces (floating sea-ice or land ice sheets) and of the water surfaces over land (rivers and lakes). In addition, it provides wind speed information over the sea surface as well as an estimation of the wave-height. In order to fulfil these objectives, the Topography Payload embarked on the Sentinel-3 spacecraft comprises: 1) A dual-frequency Radar Altimeter (SRAL), operating in Ku and C-band, with Synthetic Aperture Radar capability ensuring an improved along-track resolution along track 2) A dual-channel Microwave Radiometer (MWR), providing Wet Troposphere corrections for the Altimeter measurements 3) A GNSS receiver, a DORIS navigation receiver and a Laser Retro-Reflector for precise orbit determination This paper provides the status of the development of these instruments, together with relevant performance results obtained during the Instrument or Spacecraft integration activities. A short summary of their design and principle of operation is given, addressing in particular the Altimeter SAR mode and its advantages with respect to the more conventional LRM mode. In flight calibration principles are also described, covering SRAL internal calibration modes and other external calibration techniques. Finally, this paper details the user products of the Surface Topography Mission and gives the status of the development of the ground processing elements.