On the Three-dimensional Wind-Driven Circulation in Patos Lagoon

Abstract

The Princeton Ocean Model was used to study the three-dimensional wind-driven circulation in Patos Lagoon, throughout a nesting approach. The sea surface heights computed from a larger model domain with lower resolution were used as boundary conditions for the simulations with a smaller grid, with higher resolution. The results show that the wind causes a sea level difference of 0.08 m for winds of 4 ms-1. The northeast (southwest) wind causes an elevation (depression) at Ponta da Feitoria and a depression (elevation) at Itapoã. Arambaré is the nodal line of the system. On the continental shelf, the northeast (southwest) wind causes a depression (elevation) on the level close to the coast. The responses of the ocean and the lagoon to the wind forcing are complementary, due to the lagoon’s orientation and the earth’s rotation effect. The barotropic pressure gradient developed between these two systems is the main mechanism responsible for pumping water towards or away from the lagoon. In the central part of the lagoon, four vertical circulation cells are formed, due to topography effects. The central part of the lagoon presents surface velocities with the same orientation of the wind and a return flow close to the bottom.