Abstract
Over the past decades, the South Atlantic Ocean has experienced several changes, including a reported increase in coastal erosion and floods. This study aims to investigate the recent changes in the extreme wave events over the south-western South Atlantic (SWSA) – which hosts the most economically important harbours in South America, high oil and gas production demands, and rich biodiversity. This investigation considers not only the occurrence of extreme wave events but also extreme wave indicators that characterise the potential wave impact on offshore and coastal areas. Extreme wave events are obtained using the averaged monthly 95th percentile of significant wave height (Hs) from 1993 to 2021, combining the CMEMS global wave reanalysis and near-real-time products. Annual and seasonal statistics are derived to analyse mean and extreme wave climate and trends in the study region, focusing on Hs, peak period, and wave power. The analysis gives an overview of the wave climate in the study domain, including a discussion about seasonal differences. For a more direct application to future risk assessment and management, we perform an analysis considering the regional monitoring and warning system division established by the Brazilian Navy. We used a coastal hazard database that covers a portion of the coast to investigate how the trends given by the CMEMS wave products may impact the coastal zone. Our findings showed significant changes in the SWSA mainly associated with an increase in mean values of Hs, wave period, and consequently the wave power. Narrowing down to the coastal impact, we found an increase in the number of coastal hazards in the State of São Paulo associated with waves, which agrees with the increase in the number of extreme wave events in the adjacent ocean sector. However, the increased number of coastal events is also driven by local factors.
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