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Revista Brasileira de Meteorologia

Print version ISSN 0102-7786

Abstract

PALMEIRA, Ana Cristina Pinto de Almeida; CAMARGO, Ricardo de  and  PALMEIRA, Ronaldo Maia de Jesus. Effect of wind discretization in the modeling sea wave of western South Atlantic. Rev. bras. meteorol. [online]. 2012, vol.27, n.1, pp. 117-125. ISSN 0102-7786.  http://dx.doi.org/10.1590/S0102-77862012000100012.

This work carried out numerical simulations of gravity waves of the sea surface using the model WAVEWATCH-III version 1.18 over the Atlantic in order to evaluate the importance of detailing wind features for different sea conditions. The chosen area was delimited by parallels 18 º S and 45 º S and the meridian 35º W and 70º W, so that the center of the grid was over the RS coast. For each event, wind fields from the RAMS mesoscale model (grid of 0.34º x 0.284º and hourly output time) and from the NCEP global model (grid of 2.5º x 2.5º and temporal output every 6 hours) were inserted into the WW3 model in order to verify the influence of scales in the generation of sea surface waves. It was noted that in extreme events, the simulations overestimated the heights of the waves. Comparing to the observed in situ wind fields, it was also noticed that the integrations powered by NCEP reanalysis data showed more discrepant results than the integrations from the RAMS model. The more precise behavior when using RAMS data points out the importance of mesoscale phenomena for the generation of wave trains, which propagate in groups. During calm wind events, the wave heights were underestimated, raising two lines of action: the first is to extend the chosen domain, because this pattern seems to be associated with waves generated in a far remote region and the second is to start the WW3 with a more realistic wave field.

Keywords : Wave model; significant wave height; downscalling; Southwest Atlantic.

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