engleski

Numerical solution of the Adriatic Sea principal tidal constituents

Primary goal of the present paper has been to incorporate data-derived harmonic constants into a complex dynamic model using a variant of variational data assimilation, with a view to improve prediction of 7 dominant tidal harmonics in the Adriatic Sea. Firstly, harmonic-constant data for 6 Adriatic stations were fed into a steady state 3D forward/inverse model to furnish optimal boundary conditions (OBCs). Calculated OBCs were then used to derive individual harmonic responses, as well as to synthesise seven-harmonic boundary condition for the time stepping 3D model. A separate set of 25 stations provided control harmonic constant data. In validating the model output particular attention has been given to often-ignored tidal currents. To that end 14 current meter data records (not used in the assimilation procedure) were processed into tidal current ellipse parameters and used to examine the comparable model output. Comparison to gauge data has shown that the present solution is better than our own previous one (Janeković et al., 2003 - M2 and K1), as well as that of a recent contender (Cushman-Roisin and Naimie, 2002 - M2, S2, K1, O1). Semi-diurnal currents appear to be modelled better that the diurnal ones (generally over-predicted). High eccentricity of both data- and model-derived ellipses often impaired calculating the proper sense of rotation ; inclination of the ellipses proved to be the most robust parameter, successfully predicted for most harmonics at all depths.

numerical modeling; sea level variations; surface waves and tides

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