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. The overflow is controlled by rotational dynamics and 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 appears to be associated with the interaction of the density current with bottom-trapped waves, or possibly with interior basin modes. It appears that the forcing of the oscillation is associated with the wind, which also contains a 3-d signal. -Authors