Baroclinic circulation in the Gulf of Patras (Greece)

Three-dimensional numerical simulations, performed using the MIKE 3 FM (HD) code, have been used to study the hydrodynamic circulation of the Gulf of Patras. Simulated salient features of the summer-time simulated circulation include strong tidal currents in the main body of the Gulf, which further accelerate through the Rio–Antirio straits where an internal wave is generated, upwellings in the Gulf of Patras and Nafpaktos Bay, and the development of a central cyclonic gyre. The location of the simulated summer-time upwellings is in agreement with information reported in the literature, and the conditions under which they occur have been determined qualitatively. Winter-time simulations have also revealed upwellings at the same locations and under the same wind and tide conditions (with one exception); these have not been reported in the literature presumably because of their lack of temperature-signature. The presence of summer-time stratification produces a phase lag for the exchange flowrate at the Rio–Antirio straits, compared to the winter-time regime, due to the generation of internal waves, but has a minor effect on its magnitude. The numerical simulations have been validated against satellite infrared images and field data, which qualitatively confirm the reproduced results. •Baroclinic circulation in the Gulf of Patras is studied through numerical simulations.•Summer-time upwellings have been reproduced, providing validation to the simulations.•Previously unknown winter time upwelling sites have beenB identified.•A cyclonic gyre develops during flood tide and NE wind in stratified conditions.•The mechanism of the formation of a cold patch in the center of the gyre is clarified.