Introduction to Sentinel-6

The Poseidon-4 altimeter evolved significantly from its predecessors (Poseidon-3A and -3B instruments on board Jason-2 and -3 respectively) and features higher performance than this previous generation. It embeds a new operating mode that allows synthetic aperture radar (SAR) mode processing capability (Raney, 1998; Wingham et al., 2006; Boy et al., 2017). Poseidon-4 also features a new architecture, increasing the use of digital functions which aims at enhancing the stability of the altimeter performances. Furthermore, Poseidon-4 performs a near continuous transmission of Ku-band pulses, that allows both conventional low-resolution mode (LRM) and SAR mode data to be generated simultaneously, ensuring compatibility with previous pulse-limited altimeter missions. On top of that, Poseidon-4 includes in SAR mode an on-board range migration correction (RMC) processing, which performs a fast Fourier transform to be applied to each pulse which can be losslessly reversed on ground, to reduce SAR mode data volume to be downlinked so that high-resolution (SAR) observations could be made everywhere in the global ocean, close to the coast and for mapping rivers and lakes for hydrology purposes.   

At this stage in the ASELSU project, however, we have focused on the LRM processing over oceans. This is discussed further on the next page.

A video introduction to Sentinel-6 Operation from ESA available at:
https://www.esa.int/ESA_Multimedia/Videos/2020/09/Copernicus_Sentinel-6_in_action 

For more information, please see the following websites and references: 

• https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-6

• https://www.jpl.nasa.gov/missions/sentinel-6/

• https://podaac.jpl.nasa.gov/Sentinel-6