CoAuthors

Michaël Ablain (CLS, France); Loren Carrere (CLS, France); Amandine Guillot (CNES, France); Nicolas Picot (CNES, France); Florent Lyard (LEGOS, France); Nikita Zelensky (NASA, US); Richard Ray (NASA, US)

Mean Sea Level (MSL) is one of the main signals of interest for physical oceanographers. Since the beginning of the altimeter mission TOPEX/Poseidon, followed by Jason-1 and Jason-2 on similar orbits, MSL products became essential to the comprehension of Global ocean circulation.
At the 2010 OSTST in Lisbon, a dedicated session highlighted a strong 58.77-day signal on Jason-1 and Jason-2 MSL records whereas it was smaller on TOPEX/Poseidon. The conclusions were this signal is the aliasing of a higher frequency error inherited from the tide model correction: the semi-diurnal wave S2. The source of this error is attributed to TOPEX measurements which are assimilated in ocean tide models. When these models are used in the computation of TOPEX/Poseidon MSL, most of the error cancels. However, this error is communicated to Jason-1 and Jason-2 MSLs, which explains why it is stronger for these missions than for TOPEX/Poseidon.
Since 2010, considerable efforts have been undertaken within the ocean tide community in order to correct ocean tide S2-waves from this error, particularly in the Goddard Ocean Tide (GOT) and Finite Element Solution (FES) latest versions: GOT4.8 and GOT4.10, FES2012 and FES2014. This study aims at assessing, quantifying and characterizing the reduction of the 58.77-day error. It is the continuation of the dedicated session at OSTST 2010 completed with (i) analyses of the 58.77-day error in the latest GOT and FES releases, (ii) regional analyses in addition to the global ones, (iii) analyses on Jason-2 MSL record in addition to TOPEX and Jason-1, and (iv) the comparison of three versions of FES2014 which assimilate different sets of altimetry data to characterize the error reduction