Extending Oceananigans.jl Ocean Model Toward Regional Applications: Design and Evaluation of Radiative Open Boundary Schemes

General circulation models (GCMs) are widely used in oceanography to study climate processes and regional hydrodynamics. Recent advances in high-performance computing and modern programming languages provide new opportunities to develop flexible and efficient modeling tools. Oceananigans.jl, written in Julia, is a high-performance ocean model designed to run efficiently on both CPUs and GPUs while allowing modular and customizable configurations. This thesis contributes to extending Oceananigans.jl for regional ocean simulations by implementing radiative open boundary conditions. First, a one-dimensional advection-based scheme inspired by Orlanski-type radiation is developed and validated in an idealized configuration. The method is then extended to two dimensions using a Raymond–Kuo–type formulation and tested in a North Adriatic Sea setup forced by Copernicus Marine Service hydrodynamic fields along the open boundary. Finally, the execution behavior of the enhanced solver is examined on GPU architectures, in particular NVIDIA A100 GPUs onthe Leonardo supercomputer at CINECA, demonstrating the practical portability of Oceananigans.jl to modern GPU-based high-performance computing systems for regional ocean modeling.