Climatologia de ondas do Atlântico Sul: contribuições para a Metarea V com base na reanálise Waverys

Abstract

This work presents the development of a monthly wave climatology for METAREA V (the South Atlantic Ocean region adjacent to the Brazilian coast), based on the WAVERYS reanalysis. Twelve monthly mean maps of the parameters significant height (HS), direction (Dir), and peak period (TP) were produced, as well as wave roses for 12 locations of naval interest. Furthermore, time series were generated for Belém/PA, Recife/PE, Guanabara Bay/RJ and Rio Grande/RS, to complement the information available in the Pilot Chart Atlas and support the development of BC by the CHM. The reanalysis data have an approximate resolution of 0.2° (~22 km) and are output every 3 hours. They were preprocessed in a Python environment using specific libraries. Monthly means were calculated at each grid point for the period 1980–2022, resulting in a monthly wave atlas. Wave roses were generated from directional frequencies and HS bands. The time series were smoothed using a 30-day moving average. The results showed that the use of WAVERYS substantially improves coastal representation compared to the lower- resolution reanalysis currently used in BC (ERA-20C), filling sensitive areas that previously lacked climatological wave information. Seasonally, wave trains propagating from extratropical cyclones are the dominant factor, maintaining higher HS values in the Northeast during the boreal winter and in the South-Southeast during the austral winter. The intensity and seasonal migration of the trade winds originating from the ASAS maintain a zonal wave pattern off the east coast of Brazil and adjacent maritime areas, with higher HS and TP values during the winter months in the Southern Hemisphere. The variability and seasonal patterns of HS and Dir are reflected in the time series and wave roses. The products presented reinforce the potential of using the WAVERYS reanalysis as a source of climatological information for naval applications.