Implementation of a multi-grid operational wave forecast in the South Atlantic Ocean

This paper presents the development of an operational wave forecast in South Atlantic Ocean. The system adopts WAVEWATCH-III model version 6.07 using ST4 physics and its implementation follows four steps: (1) assessment wind forecasts products (GFS/NOAA ICON/DWD); (2) investigation source-terms model; (3) sensitivity tests involving spectral spatial resolutions combined with analysis different inputs calibration parameters; (4) definition best mosaic multiple grids fine-tuning for each grid input, 6-month simulations assessed against altimeter data. evaluation discussion are performed terms speed (U10) significant height (Hs). balance between accuracy computational cost is investigated. results highlight importance multi-grid scheme WAVEWATCH-III, even at large domains deep waters. It enabled Atlantic, very heterogeneous metocean conditions, to be divided into two where resolution source-term parameters could obtained. Furthermore, it reduced cost, which allowed independent per cycle, forced by high-quality winds GFS/NOAA ICON/DWD. validation Hs showed correlation coefficients around 0.96, scatter errors 11%, RMSE 0.32 0.34 m. performance compromised longer leads associated strong winds.