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

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 presen...

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Bibliographic Details
Published in:Deep-sea research. Part I, Oceanographic research papers Oceanographic research papers, 2014-10, Vol.92, p.75-84
Main Authors: von Appen, Wilken-Jon, Koszalka, Inga M., Pickart, Robert S., Haine, Thomas W.N., Mastropole, Dana, Magaldi, Marcello G., Valdimarsson, Héðinn, Girton, James, Jochumsen, Kerstin, Krahmann, Gerd
Format: Article
Language:English
Subjects:
Atlantic Meridional Overturning Circulation
Circulation
Climate
Coastal oceanography, estuaries. Regional oceanography
Denmark Strait overflow water
Density
Earth, ocean, space
East Greenland Spill Jet
Exact sciences and technology
External geophysics
Marine
Marine ecology
Mathematical models
Ocean circulation
Ocean currents
Oceanography
Pathways
Physics of the oceans
Sea currents
Shelf Basin interaction
Shelves
Spills
Straits
Thermohaline structure and circulation. Turbulence and diffusion
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Summary: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. •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.
ISSN:0967-0637
1879-0119
DOI:10.1016/j.dsr.2014.06.002