Toward multiscale oceanic simulations based on mesh refinement strategies with local adaptation of dynamics and physics

This talk describes new theoretical and algorithmic developments of the Coastal and Regional Ocean COmmunity model (CROCO). A particular emphasis for this model is the consistent representation of the scale range of the oceanic submesoscale currents (SMCs). While the high part of the SMC spectrum corresponds to hydrostatically balanced dynamics, the finest scales of the SMC spectrum are associated with nonhydrostatic dynamics that is not accessible for primitive equation (PE) models. To advance our knowledge on the energy transfers across the SMCs spectrum, we are interested here in the implementation of a modeling strategy that explicitly simulates important fine-scale non-hydrostatic processes (e.g. primary instabilities leading to direct turbulent cascade, solitary waves generation and dissipation, etc) and evaluates their feedback to larger scales. The CROCO model combines a PE solver and a non-hydrostatic compressible solver as well as a 2-way nesting capability. We will discuss the numerical challenges to implement a multiscale ocean modeling strategy based on a block-structured mesh refinement approach with local adaptation of model equations, numerical methods and physical closures to allow a consistent downscaling and upscaling in selected areas of interest.