The East Greenland Spill Jet as an important component of the Atlantic Meridional Overturning Circulation

• Published in: Deep Sea Research Part I: Oceanographic Research Papers
• Main Authors: von Appen, Wilken-Jon, Koszalka, Inga Monika, Pickart, Robert S., Haine, Thomas W.N., Mastropole, Dana, Magaldi, Marcello G., Valdimarsson, Héðinn, Girton, James, Jochumsen, Kerstin, Krahmann, Gerd
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2014
• Subjects: Greenland; Irminger Sea; Denmark Strait; East Greenland; Labrador Sea
• Online Access: https://oceanrep.geomar.de/id/eprint/25378/; https://oceanrep.geomar.de/id/eprint/25378/1/1-s2.0-S0967063714001022-main.pdf; https://oceanrep.geomar.de/id/eprint/25378/2/mmc1.gif; https://doi.org/10.1016/j.dsr.2014.06.002

Highlights: • Mooring observations show the East Greenland Spill Jet to be ubiquitous. • It is fed by classical DSOW in Denmark Strait, shelf water, and Irminger Sea water. • Its transport is similar to the classical DSOW plume. • It is the origin of a large fraction of the water in the Labrador Sea Water density range. Abstract: The recently discovered East Greenland Spill Jet is a bottom-intensified current on the upper continental slope south of Denmark Strait, transporting intermediate density water equatorward. Until now the Spill Jet has only been observed with limited summertime measurements from ships. Here we present the first year-round mooring observations demonstrating that the current is a ubiquitous feature with a volume transport similar to the well-known plume of Denmark Strait overflow water farther downslope. Using reverse particle tracking in a high-resolution numerical model, we investigate the upstream sources feeding the Spill Jet. Three main pathways are identified: particles flowing directly into the Spill Jet from the Denmark Strait sill; particles progressing southward on the East Greenland shelf that subsequently spill over the shelfbreak into the current; and ambient water from the Irminger Sea that gets entrained into the flow. The two Spill Jet pathways emanating from Denmark Strait are newly resolved, and long-term hydrographic data from the strait verifies that dense water is present far onto the Greenland shelf. Additional measurements near the southern tip of Greenland suggest that the Spill Jet ultimately merges with the deep portion of the shelfbreak current, originally thought to be a lateral circulation associated with the sub-polar gyre. Our study thus reveals a previously unrecognized significant component of the Atlantic Meridional Overturning Circulation that needs to be considered to understand fully the ocean׳s role in climate.