Florent Lyard (LEGOS, France); Romain Baghi (CLS, France); Nicolas Picot (CNES, France)

Thanks to its current accuracy and maturity, altimetry is considered as a fully operational observing system dedicated to scientific and operational applications. In order to access the targeted ocean signal, altimeter measurements are corrected for several geophysical parameters among which the ocean tide correction is one of the most critical. Global ocean and loading tide models GOT and FES are operationally used in present altimeter GDRs. These global ocean tide model are barotropic models; by essence they do not correct from the internal tides signature at the surface.

Indeed internal tides can have a signature of several cm at the surface with wavelength about 50-250 km for the first mode. The perspective of SWOT mission and high resolution ocean measurements make the correction of these small scale signals a challenge, as we need to be able to separate tides from other oceanic signals.

In this study, we propose a detailed comparison and validation of several internal tides corrections developed by different scientific teams (Egbert and Erofeeva 2015, Ray and Zaron 2016, Zaron 2016, Zhao et al. 2012, and likely other models); we focus on the coherent internal tide signal for M2 wave and we also try to estimate the residual non-coherent signal.
Validation process is based on a statistical analysis, on a comparison to multi-missions altimetry including Jason-2, AltiKa and Cryosat-2 data and on a spectral analysis approach.