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Modelling ocean currents in the Northern Adriatic Sea

March 31, 2014

Ocean circulation in the northern Adriatic Sea is characterised by the interactions of tidal currents, bathymetric constraints, wind forcing and density gradients induced by river input and heat exchange. The MIKE 3/21 modelling system, together with measurements of wind, waves, currents and water levels at one location, has been used to investigate the currents dynamics of the northern Adriatic basin and to assess model sensitivity to the parameterisation of different processes and implementation strategies. An assessment has been carried out against available in-situ observations (waves, currents, surface elevation, and water temperature), and also in comparison with a high-resolution modelling system (COAWST) implemented in the same area during the corresponding period. The MIKE 3/21 system was implemented for a 1-year simulation period and validation of surface elevation, wind, and waves with data indicated a good model performance, statistically very similar to the COAWST implementation. Depth-averaged, surface and bottom currents were more difficult to reproduce by both models, with the observed high variability not being fully captured by the model systems. Some of the differences between the models results may be due to model configuration, spatial resolution and the way they treat atmosphere–ocean momentum and heat transfers, turbulence, and are therefore discussed in the paper. From the thorough analysis of MIKE 3/21 system, wind is found to be the main forcing factor inducing currents in the northern Adriatic; tides and baroclinic motions were of second order, although some specific events seems to be forced by these processes. Waves were found to be highly correlated with local wind, and a rather weak wave–current interaction was observed. Even if the inclusion of wave effects trough radiation stress did not seem to lead to significant improvements in the modelled currents with MIKE 3/21, the full wave–ocean coupling in COAWST was significant in explaining small scale features, especially in the Gulf of Venice. Spectral and SVD analysis showed energy around diurnal and semidiurnal frequencies and that about 50% of variance in the current profile was explained by the first mode, which was well captured by both modelling systems.

Bolaños R, Tornfeldt Sørensen JV, Benetazzo A, Carniel S, Sclavo M, in press: Modelling ocean currents in the Northern Adriatic Sea, Continental Shelf Research, doi:10.1016/j.csr.2014.03.009. Article (subscription required).

 

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