Simultaneous estimation of Ocean mesoscale and coherent internal tide Sea Surface Height signatures from the global Altimetry record

Abstract. This study proposes an approach to estimate the Ocean Sea Surface Height signature of coherent internal tidesfrom 25 years of along-track altimetry record, with a single inversion over time, resolving both internal tide contributions andmesoscale eddy variability. The inversion is performed through reduced-order basis with conjugate gradient resolution. Theparticularity of this approach is to mitigate the potential aliasing effects between mesoscales and internal tide estimation fromthe uneven altimetry sampling (observing the sum of these components) by accounting of their statistics simultaneously, while other methods generally use a prior for mesoscales. The four major tidal components are considered (M2,K1,S2,O1) over theperiod 1992–2017 on a global configuration. From the solution, we use altimetry data after 2017 for an independent validation,to evaluate the benefits of the simultaneous inversion, and also to compare the skills with an existing model.