The Faroe-Bank Channel deep-water overflow

In the late 1950s it was recognised that a considerable transport of water from the deeper reaches of the Norwegian Sea into the Atlantic takes place through the Faroe-Bank Channel, which thereby serves as an important source for the renewal of the North Atlantic Deep Water. Consequently, substantial efforts have, over the past decades, been dedicated towards quantifying the overflow as well as clarifying the underlying dynamics. In the present review, an attempt is made to summarise the main body of the observational results as well as some theoretical considerations regarding the dynamical mechanisms. The most prominent characteristic of the Faroe-Bank Channel overflow is that it is a persistent phenomenon with a yearly average deep-water (viz. T<5°C) transport of around 2 Sv. Using inviscid rotating hydraulics, the flow through the controlling section at the sill, furthermore, can be reasonably well predicted on the basis of upstream conditions in the Norwegian Sea. After passing the threshold the descending overflow plume is subject to intense mixing, a process very much in the focus of ongoing research.