Tridimensional Wave-Resolving Modeling of Nearshore Dynamics

Patrick Marchesiello, IRD Institute of Research for Development, LEGOS, Toulouse, France, Rachid Benshila, CNRS, Paris Cedex 16, France, Francis Auclair, Laboratoire d'Aérologie - Observatoire Midi Pyrénées, Toulouse, France, Rafael Almar, Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (LEGOS), IRD, Toulouse, France and James C McWilliams, University of California, Los Angeles, Atmospheric and Oceanic Sciences, Los Angeles, United States
Abstract:
CROCO (Coastal and Regional Ocean Community model) is a new oceanic modeling system built upon ROMS with a non-Boussinesq kernel. CROCO is designed for solving fine-scale processes from the regional ocean to littoral zone with capabilities for LES-type simulations in realistic configurations, including coupling with the atmosphere, sediments and ecosystems. Particular attention is given to numerical accuracy, high-performance computing (optimization, scalability), portability and easy access (http://www.croco-ocean.org). This communication first presents a quick overview of the nonhydrostatic CROCO solver with a non-Boussinesq (compressible) approach, before addressing its application to nearshore dynamics. First, its ability to simulate surface gravity wave propagation and nearshore breaking is validated against laboratory experiment. Second, we present and analyse a full 3D wave-resolving simulation of alongshore currents generated by oblique waves with frequency and directional spreading (allowing short crested waves). The generation of surfzone eddies is shown to differ considerably from that produced by either 3D wave-averaged or 2D wave-resolving models, owing to the vertical structure of breaking and nature of 3D turbulence.
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