A preliminary study on the internal tides of the gulfs of Patras and Korinthos, Greece

The semi-diurnal baroclinic tide in the semi-closed channel which lies between the Greek Mainland and Peloponnesus has been investigated. It appears to be generated in the centre of the channel, where a bottom step topography exists. At a location 8 km away from the source, its amplitude reaches 3 m during spring tides. Modal decomposition of the baroclinic tide indicated that the first mode accounts for 80% of the energy while almost all of the energy is accounted for by the first three vertical modes. During the observational period several upwelling events occurred. These events caused baroclinic tidal energy to disappear through the weakening of the stratification within 10–20 h. The higher modes dissipated much faster than the first mode which continued to gain energy until the isopycnal tilt reached a maximum. The available set of data indicates that the baroclinic oscillations may not be an internal Kelvin-type wave.