Western South Atlantic Climate Experiment

Extreme near-surface winds and ocean waves affect several activities over coastal and oceanic regions, such as offshore oil and gas industry, management of port operations, installation of renewable energy systems, and navigation. Our objective is to evaluate the ability of reanalysis/satellite data to reproduce local features of wind speed at 10 m height and significant wave height (SWH), and to assess the climatology (mean and extreme) of regional downscalings using WRF and RegCM4 for the atmosphere and WW3 for the ocean waves over the western South Atlantic. For the present climate, WRF and RegCM4 are forced by two CMIP5 global climate models (HadGEM2-ES and MPI-ESM-MR) and reanalysis, while WW3 is forced by the winds from the downscalings. We found that: (i) CCMP and WAVERYS have a more realistic representation of, respectively, the wind speed and SWH observed by buoys and platforms over the southeastern Brazilian basins; (ii) near the southeastern coast of Brazil, austral spring and winter have the more intense wind and wave extremes; (iii) RegCM4 and WRF present opposite biases over the southwestern South Atlantic, i.e., RegCM4 (WRF) overestimates (underestimates) the wind speed extremes, except for the region of Santos basin where both overestimate the extremes in austral summer and spring; and (iv) the SWH is closer to reanalysis when WW3 is forced by winds from WRF. This first assessment of the mean and extreme winds and oceanic waves from regional climate downscaling provides confidence and knowledge for further investigation on climate projections over the region.