Wave climate at Babitonga Bay using hybrid downscaling

Abstract

This study presents a comprehensive analysis of the wave climate in Babitonga Bay, Brazil, using a hybrid downscaling approach. By integrating dynamic and statistical techniques, we effectively transferred CAWCR oceanic wave reanalysis data (1979 to 2022), for a point on the continental shelf to the coastal region, focusing on the ports of São Francisco do Sul and Itapoá. The methodology included selecting representative sea states, propagating them with the SWAN wave model, and reconstructing the time series using radial basis function interpolation. Validation against observational data at three ADCP stations showed that the hybrid downscaling results more accurately captured wave parameters compared to CAWCR hindcast, particularly at shallow water stations (4–7 m depth) where the downscaled significant wave heights closely tracked measured values, highlighting the effectiveness of the downscaling approach. Furthermore, the analysis reveals a bimodal wave climate at each port, distinguishing between the persistent, operational wave conditions and less frequent but distinct swell events from a secondary direction, a critical insight for risk assessment. The study provides detailed 2D and 3D analyses of wave parameters such as significant wave height ($H_s$), peak period ($T_p$), and wave direction, revealing crucial insights into wave age and height dynamics in São Francisco do Sul. These findings offer valuable data for coastal management and infrastructure planning in Babitonga Bay and similar regions. The hybrid downscaling methodology presented here proves to be an efficient and reliable tool for characterizing wave climate in port regions, providing essential information for safe navigation and port operations in São Francisco do Sul and Itapoá.