A set of 3-D nested models for tidal propagation from the argentinean continental shelf to the Río de la Plata estuary - Part I. M2

Abstract

As a contribution to the UNDP/GEF project 'Environmental Protection of the Río de la Plata and its Maritime Front', the three-dimensional primitive equation Hamburg Shelf Ocean Model is being implemented for forecasting purposes. As a first step a study of the tidal propagation was done. Data for the estuary were gained through a set of three one-way nested models. Simulations were started with a large-scale model covering the Argentinean and Uruguayan and part of the Brazilian continental shelves. This model provides boundary conditions to a smaller scale model of the Río de la Plata and adjacent continental shelf, which in turn is used to force a small-scale high-resolution model of the Río de la Plata estuary. Model sensitivity to different boundary conditions and to model parameters was investigated. Solutions are not sensitive to the two different boundary conditions tested, derived from global data assimilating models. It results also not sensitive to lateral diffusion but to bottom friction. M2 tidal wave propagates northwards as a Kelvin wave, with amplitudes reaching almost 4 m in Southern Patagonia and a few centimeters at the Río de la Plata estuary. Simulation results for the M2 component propagation were validated using all tidal gauge data available and several currents observations, resulting in a very good agreement. These simulations have permitted, therefore, the construction of more reliable model derived cotidal, corange and tidal currents charts. The non-linear transfer of energy from semidiurnal to higher order harmonics was mapped. It can reach very high values at some locations of the Patagonian coast. Tidal energy dissipation derived from the simulations shows that it constitutes an important amount of the globally estimated one.