The contribution of the Denmark strait overflow to the deep North Atlantic

Swift, JH, Aagaard K, Malmberg SA.  1980.  The contribution of the Denmark strait overflow to the deep North Atlantic. Deep-Sea Research Part a-Oceanographic Research Papers. 27:29-42.


Dense water formed in the seas north of the Greenland-Scotland ridge system overflows the ridges and sinks in the North Atlantic. The overflow through Denmark Strait provides the densest component of the Northwest Atlantic Bottom Water, a principal component of the North Atlantic Deep Water. Vertical hydrographic trends in the deep northwest Atlantic differ markedly, however, from those at and north of the Denmark Strait sill. Norwegian Sea Deep Water (NSDW), the densest water mass found north of the sill, contributes less than 10% to the overflow through Denmark Strait. Instead, the principal dense component of this overflow is an intermediate water of arctic origin, at slightly under 34.9% and about 5 T.U. This water is in part formed in winter at the sea surface in the Iceland Sea. The remainder is of more northerly origin, carried southward by the East Greenland Current. Though this intermediate water mass is only slightly less dense than NSDW, its residence time (3 to 4 years) in the waters north of Iceland is an order of magnitude less than that of NSDW. Hence, the deep North Atlantic may be more sensitive to climatological and ecological perturbations than hitherto believed.