The Impact of the Resolution of Wind Fields on Predictive Wave Models

Abstract: In this paper the effects of the spatial and temporal resolutions of the wind field on the forecasting of wind waves are discussed. Three different meteorological events that generated waves in the Campos Basin (south-eastern Brazil) were simulated using the mesoscaleBrazilian Regional Atmospheric Modeling System(BRAMS) with high spatial resolutions of 20, 60, 100, 300 and 600 km and temporal resolutions of 1, 3 and 6 hours and the results were entered into WAVEWATCH (WW3). Two of these events were associated with the formation of extratropical cyclones in the South Atlantic which propagated with velocities above the local average and with large fetches. In the third event, the waves were associated with small fetches generated by the Subtropical South Atlantic Anticyclone (ASAS). The selection of these meteorological events, each with different physical characteristics, allowed us to evaluate the performance of the wave model as a function of the resolution of the wind field input. Our results indicate that the best spatial resolution in terms of computational cost versus error is 60 km,whereas the different time resolutions impose inconspicuous impact on the wave forecast.