The dense overflow waters of the Nordic Seas are an integral link and necessary diagnostic for the stability of the Atlantic Meridional Overturning Circulation (AMOC). The pathways feeding the overflow remain, however, poorly resolved.
In a new study, scientists investigated the pathways that water takes to feed one of the world’s largest “waterfalls” in the North Atlantic Ocean: the Faroe Bank Channel Overflow into the deep North Atlantic.
They discovered a previously unrecognized ocean current that transports water to this significant waterfall. They also identified a surprising path of the cold and dense water flowing at depth, which led to the discovery of this new ocean current.
Léon Chafik, the lead author of the paper and a research scientist at Stockholm University, Sweden, said, “This new ocean current and the path it takes toward the Faroe Bank Channel are exciting findings.”
Co-author Thomas Rossby, emeritus professor at the URI Graduate School of Oceanography, said, “The two discoveries reported here, in one of the best-studied areas of the world ocean, is a stark reminder that we still have much to learn about the Nordic Seas. This is crucial given the fundamental role they play in the major glacial-interglacial climate swings.”
Past studies have shown that these cold waters turn directly into the Faroe-Shetland Channel. In this new study, scientists show that there exists another path into the Faroe-Shetland Channel. They show that water can take a longer route to the continental margin outside Norway before turning south heading toward this significant waterfall.
Chafik said, “Revealing this newly identified path from available observations was not a straightforward process and took us a good deal of time to piece together.”
“This new path depends on prevailing wind conditions. It seems that atmospheric circulation plays a major role in orchestrating the identified flow regimes.”
The study also suggests that much of the water that will end up in the Faroe Bank Channel is not transported along the western side of the Faroe-Shetland Channel (the region the water flows through before reaching the Faroe Bank Channel), as previously thought. Instead, most of this water comes from the eastern side of the Faroe-Shetland Channel, where it is transported by a jet-like and deep-reaching ocean current.
Chafik said, “This was a curious but fascinating finding, especially since we are aware that a very similar flow structure exists in the Denmark Strait. We are pleased that we were able to identify this new ocean current both in observations and a high-resolution ocean general circulation model.”
“Because this newly discovered flow path and ocean current play an important part in the ocean circulation at higher latitudes, its discovery adds to our limited understanding of the overturning circulation in the Atlantic Ocean. This discovery would not have been possible without many institutional efforts over the years.”
- Chafik, L., Hátún, H., Kjellsson, J. et al. Discovery of an unrecognized pathway carrying overflow waters toward the Faroe Bank Channel. Nat Commun 11, 3721 (2020). DOI: 10.1038/s41467-020-17426-8