Observations of a Density-driven Recirculation of the Scottish Coastal Current in the Minch

In April/May 1995, five satellite-tracked drifters, drogued at 15 m depth, were deployed in the southern part of the channel (the Minches) between the mainland of Scotland and the Outer Hebridean islands. Drifter trajectories provide direct evidence for a near-surface, cyclonic flow around the South Minch consistent with a baroclinic flow of buoyant, fresh coastal water around a tongue of dense, saline Atlantic water which extends into the centre of the channel from the south. This results in the southward recirculation of part of the north-flowing Scottish coastal current which is then diverted to flow to the west of the Outer Hebridean island chain. The results point to the necessity to include baroclinicity in hydrodynamic models of the region. The circulation pattern also has implications for the dispersal of contaminants and planktonic larvae, including those of the commercially important shellfish, Norway lobster (Nephrops norvegicus).