Observations of the mass and flow field at Porcupine Bank

During spring 1994 and summer 1995 hydrographic transects across the Porcupine Bank, an elliptical topographic structure adjoining the shelf-edge west of Ireland, were carried out to investigate the thermohaline properties and flow field characteristics in the vicinity of the bank. The CTD observations show a dome-like deformation of the temperature and density field together with an intrusion of cold, dense water above the bank summit. Additional acoustic current measurements in summer 1995 indicate that the dome-like perturbation of the mass field is accompanied by an anti-cyclonic, bottom-intensified circulation along the flanks of the bank. The doming of the near-bank temperature and density field and the eddy-like pattern of the flow field in summer 1995 may result from a Taylor column formation. It is suggested that a persistent Taylor column circulation around Porcupine Bank provides an important mechanism for the retention of pelagic eggs and larvae of the various marine species spawning in the area.