Evaluation of the Seasonal Variations in the Residual Circulation in the Ría of Vigo (NW Spain) by Means of a 3D Baroclinic Model

A 3D baroclinic model has been applied to study residual circulation in the Ría of Vigo (NW Spain) under different seasonal conditions. Winter, spring and non-upwelling summer conditions have been simulated. The use of a 3D model allows the spatial structure of residual circulation to be studied, both horizontaly and verticaly, and the combined effects of bathymetry, freshwater runoff, etc. to be monitored. A two-layered circulation was obtained in all situations, which is in good agreement with the partially-mixed condition of the estuary. This circulation is enhanced with increasing freshwater runoff, while its decrease makes the pattern not to be observed in the outermost part of the Ría. The zero residual current level depth has been estimated in all the situations, and the results have been compared to those obtained in the same conditions with a box model, finding a good agreement.