The Iceland-Faroe Slope Jet: a conduit for dense water toward the Faroe Bank Channel overflow

Stefanie Semper,Hjálmar Hátún,Karin Margretha H Larsen,Bogi Hansen,Robert S Pickart,Kjetil Våge

doi:10.1038/s41467-020-19049-5

Abstract

Dense water from the Nordic Seas passes through the Faroe Bank Channel and supplies the lower limb of the Atlantic Meridional Overturning Circulation, a critical component of the climate system. Yet, the upstream pathways of this water are not fully known. Here we present evidence of a previously unrecognised deep current following the slope from Iceland toward the Faroe Bank Channel using high-resolution, synoptic shipboard observations and long-term measurements north of the Faroe Islands. The bulk of the volume transport of the current, named the Iceland-Faroe Slope Jet (IFSJ), is relatively uniform in hydrographic properties, very similar to the North Icelandic Jet flowing westward along the slope north of Iceland toward Denmark Strait. This suggests a common source for the two major overflows across the Greenland-Scotland Ridge. The IFSJ can account for approximately half of the total overflow transport through the Faroe Bank Channel, thus constituting a significant component of the overturning circulation in the Nordic Seas.

Highlights

Dense water from the Nordic Seas passes through the Faroe Bank Channel and supplies the lower limb of the Atlantic Meridional Overturning Circulation, a critical component of the climate system
Overflow water formed in the eastern part of the Nordic Seas is referred to as Atlantic-origin water, whereas that formed in the interior of the western basins is referred to as Arctic-origin water, which is the densest contributor to the lower limb of the AMOC3,7
The Atlantic-origin overflow in Denmark Strait is supplied by two branches of the East Greenland Current[8,13], whereas the Arctic-origin overflow is advected by the North Icelandic Jet (NIJ)[7,8,14] originating northeast of Iceland[7,15]

Summary

Introduction

Dense water from the Nordic Seas passes through the Faroe Bank Channel and supplies the lower limb of the Atlantic Meridional Overturning Circulation, a critical component of the climate system. Using high-resolution hydrographic/velocity measurements from a September 2011 shipboard survey[28,29,30,31] (Fig. 1b), we identified a spatially coherent eastward flow between northeast Iceland and the Faroe Islands.

Results

Conclusion