Variable source regions of Denmark Strait and Faroe Bank Channel overflow waters

The pathways of the water that overflows the Greenland—Scotland Ridge and their source regions are studied with an ocean circulation model. Depending on the size of wind stress curl around Iceland, different water mass properties are found in the less dense fraction of the overflows on both sides of Iceland. Although in both cases, this fraction contributes to only a small part of the overflow, their pathways and associated source regions characterize also changes in the pathways of the denser fractions which is confirmed by backward float experiments. In detail, large Denmark Strait overflow during high wind stress curl conditions is associated with a primary pathway along the East Greenland Current with one branch encircling the Greenland Sea that is supplied by regions further southward while the other branch enters through Fram Strait. During low forcing conditions, the source region shifts into the Iceland Sea associated with a reversal of a current north of Iceland. The Faroe Bank Channel overflow is primarily fed by sources in the Norwegian Sea with water flowing southward along the Norwegian shelf. A smaller contribution that is enhanced during high forcing follows along the Jan Mayen Ridge and provides water from the Iceland Sea and the Greenland Sea.