DENSE OVERFLOW INTO A LARGE SILLED EMBAYMENT - TIDAL MODULATION, FRONTS AND BASIN MODES

A dense bottom overflow into a 100-km scale silled embayment has been observed for a 70-day period using a coherent array of current meters and thermistor chains. As the internal Rossby radius is less than the width of the bay, the overflow is controlled by rotational dynamics. T he flow is strongly modulated by the tide at diurnal, semi-diurnal and fortnightly periods. This causes a series of cold temperature fronts, associated with separate overflow events, to pass through the mooring array. The overflow is also modulated at periods of 2-3 days. This ap pears to be associated with the interaction of the density current wit h bottom-trapped waves, or possibly with interior basin modes. It appe ars that the forcing of the oscillation is associated with the wind, w hich also contains a 3-d signal.