Damien Allain (CNRS/LEGOS, France); Cyril Nguyen (CNRS/LA, France); Yves Soufflet (IRD/LEGOS, France)

The approach developed in LEGOS to address the internal tides issue for future altimetry correction is based upon frequency-domain, hydrodynamical modeling (T-UGOm unstructured grid model). It is based on a 3D wave equation, where level displacements and periodic density anomaly (due to advection) are the primary unknowns. Frequenccy- domain solver coupled to unstructured grids allows for dramatically reducing the numerical cost of internal tides modelling, in terms of computational time and state vector archive volume. Recently, it has been validated in an academic study (COMODO project, funded by ANR) that includes 3 different types of stratification (and internal tide regime). The first realistic simulations are now being tested, and will be presented. The most challenging issue in realistic modelling remains the size of the linear system to be solved (sparse matrices containing over 1 billion non-zero coeffcicients) and performances of various sparse system solvers will be discussed in the perspective of practical use in regional and/or global altimetry product processing.