Future trends of near-surface winds over the southwestern South Atlantic in two regional climate models

Monitoring near-surface winds near coastal areas is really important since it affects not only the population living nearby but also the energetic sector, such as oil and wind power industries. As an effort to understand the future wind trends in a changing climate, this study presents results from the project Western South Atlantic Climate Experiment for the middle of the century (2031 to 2060); here, future projections of near-surface winds and their extremes over the western South Atlantic are evaluated from regional dynamic downscaling by using two distinct models (WRF and RegCM4) forced by two global climate models (HadGEM2-ES and MPI-ESM-MR) under the worse RCP8.5 warming scenario. In general, the trends show a slight decrease of 0.1 to 0.3 m/s in the mean wind speed for both models over the southwestern South Atlantic adjacent to the continent (between 25º and 35ºS in RegCM4 and 15º and 25ºS in WRF). For the extremes the decrease is amplified, reaching 0.5 m/s; the only exception occurs for WRF forced by HadGEM2, in which there is no trend signal southern 25ºS. For the present climate, WRF and RegCM4 have opposite wind speed biases over the South Atlantic, which propagates to the ocean waves simulation, especially for the extremes. Therefore, in order to reduce the bias propagation, an adjustment of the upper-quantiles of the wind speed (i.e. the extremes) was applied to the present climate simulated winds, which showed an improvement for intense wind speeds. After bias corrections, the future trends of wind speed are also explored.