CoAuthors

Michaël Ablain (CLS, Space Oceanography Division, France); Loren Carrere (CLS, Space Oceanography Division, France); Nicolas Picot (CNES, France); Mathilde Cancet (Noveltis, France); Florent Lyard (LEGOS, France); M. Joana Fernandes (Faculdade de Ciências, Universidade do Porto, Portugal); Richard Ray (NASA Goddard Space Flight Center, USA)

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.
Recent works on Global MSL time series highlight a strong 58.77-days signal on Jason-1 and Jason-2 whereas it is smaller on TOPEX/Poseidon. The present study shows this signal is the aliasing of a higher frequency error inherited from the tide model correction: the semi-diurnal wave S2. Several tide model corrections have been compared including GOT (Goddard/Grenoble Ocean Tide, GSFC/NASA) and FES (Finite Element Solution, LEGOS/Noveltis/CLS).
Results suggest TOPEX/Poseidon MSL -without tide corrections- contains an error due to the semi-diurnal wave S2. It is then assimilated to tide model corrections using TOPEX/Poseidon data. When these corrections 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. The analysis also highlights the efforts made to remove this error in the latest ocean tide models.