A Decade of Annual Arctic DOC Export With Polar Surface Water in the East Greenland Current

<p>Greenland Ice Sheet melt and&#160;freshening of the Arctic Ocean lead to increased discharge of freshwater into the East Greenland Current. If this additional freshwater reaches the convective regions of the Subpolar North Atlantic it could weaken deep mixing and affect the strength of the Atlantic Meridional Overturning Circulation. In particular, freshwater exported away from the South-East Greenland shelf could affect deep convection in the Irminger Sea, which has recently been shown to have a key role in the Atlantic overturning circulation. Though export of fresh shelf surface water is well observed west of Greenland, there is still little insight into surface water export from the East Greenland shelf to the Irminger Sea.</p><p>The East Greenland Current Drifter Investigation of Freshwater Transport drifter deployment conducted in August 2019 at 65&#176;N on the eastern side of Greenland, resulted in five out of 30 drifters being exported away from the east Greenland shelf, four of which were exported at Cape Farewell. The specific wind regime at Cape Farewell is a potential driving factor for enhanced freshwater export in the area. While persistent south-eastward barrier winds push surface waters to the coast over most of the eastern shelf, Cape Farewell experiences strong eastward wind events such as tip-jets that could cause off-shelf export. Using wind data from the ERA-5 atmospheric reanalysis, we compute Ekman transport along the east Greenland shelf. We find greater probability for off-shelf Ekman transport at Cape Farewell than along the rest of the shelf, confirming that the area is the most likely to contribute to wind-driven freshwater export to the Irminger Sea. Wind and surface velocity data from a high-resolution model (2 km) are used to further investigate and quantify freshwater export at Cape Farewell and how it relates to local wind events.</p>

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Wind forcing of salinity anomalies in the Denmark Strait overflow

Ocean Science ◽

10.5194/os-7-821-2011 ◽

2011 ◽

Vol 7 (6) ◽

pp. 821-834 ◽

Cited By ~ 6

Author(s):

S. Hall ◽

S. R. Dye ◽

K. J. Heywood ◽

M. R. Wadley

Keyword(s):

General Circulation ◽

Thermohaline Circulation ◽

Circulation Model ◽

Ocean General Circulation Model ◽

Mixing Processes ◽

East Greenland ◽

The North ◽

East Greenland Current ◽

Denmark Strait ◽

Salinity Anomaly

Abstract. The overflow of dense water from the Nordic Seas to the North Atlantic through Denmark Strait is an important part of the global thermohaline circulation. The salinity of the overflow plume has been measured by an array of current meters across the continental slope off the coast of Angmagssalik, southeast Greenland since September 1998. During 2004 the salinity of the overflow plume changed dramatically; the entire width of the array (70 km) freshened between January 2004 and July 2004, with a significant negative salinity anomaly of about 0.06 in May. The event in May represents a fresh anomaly of over 3 standard deviations from the mean since recording began in 1998. The OCCAM 1/12° Ocean General Circulation Model not only reproduces the 2004 freshening event (r=0.96, p<0.01), but also correlates well with salinity observations over a previous 6 year period (r=0.54, p<0.01), despite the inevitable limitations of a z-coordinate model in representing the mixing processes at and downstream of the Denmark Strait sill. Consequently the physical processes causing the 2004 anomaly and prior variability in salinity are investigated using the model output. Our results reject the hypotheses that the anomaly is caused by processes occurring between the overflow sill and the moorings, or by an increase in upstream net freshwater input. Instead, we show that the 2004 salinity anomaly is caused by an increase in volume flux of low salinity water, with a potential density greater than 27.60 kg m−3, flowing towards the Denmark Strait sill in the East Greenland Current. This is caused by an increase in southward wind stress upstream of the sill at around 75° N 20° W four and a half months earlier, and an associated strengthening of the East Greenland Current.

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Paleoceanographic evolution of the SW Svalbard margin (76°N) since 20,000 14C yr BP

Quaternary Research ◽

10.1016/j.yqres.2006.07.002 ◽

2007 ◽

Vol 67 (1) ◽

pp. 100-114 ◽

Cited By ~ 156

Author(s):

Tine L. Rasmussen ◽

Erik Thomsen ◽

Marta A. Ślubowska ◽

Simon Jessen ◽

Anders Solheim ◽

...

Keyword(s):

Surface Water ◽

Water Mass ◽

Atlantic Water ◽

Subsurface Water ◽

Planktic Foraminifera ◽

Surface Conditions ◽

Polar Surface ◽

Warm Core ◽

Heinrich Event ◽

Benthic Environment

AbstractTwo cores from the southwestern shelf and slope of Storfjorden, Svalbard, taken at 389 m and 1485 m water depth have been analyzed for benthic and planktic foraminifera, oxygen isotopes, and ice-rafted debris. The results show that over the last 20,000 yr, Atlantic water has been continuously present on the southwestern Svalbard shelf. However, from 15,000 to 10,000 14C yr BP, comprising the Heinrich event H1 interval, the Bølling–Allerød interstades and the Younger Dryas stade, it flowed as a subsurface water mass below a layer of polar surface water. In the benthic environment, the shift to interglacial conditions occurred at 10,000 14C yr BP. Due to the presence of a thin upper layer of polar water, surface conditions remained cold until ca. 9000 14C yr BP, when the warm Atlantic water finally appeared at the surface. Neither extensive sea ice cover nor large inputs of meltwater stopped the inflow of Atlantic water. Its warm core was merely submerged below the cold polar surface water.

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The Cold and Heavy Bottom-Water of the Barents Sea Polar Surface Water of Northern Barents Sea

Northern Waters ◽

10.1017/cbo9781107281035.004 ◽

2014 ◽

pp. 20-56

Author(s):

Fridtjof Nansen

Keyword(s):

Surface Water ◽

Bottom Water ◽

Barents Sea ◽

Polar Surface ◽

The Barents Sea

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On the velocity field of the East Greenland Current

Deep Sea Research Part A Oceanographic Research Papers ◽

10.1016/0198-0149(88)90086-6 ◽

1988 ◽

Vol 35 (8) ◽

pp. 1335-1354 ◽

Cited By ~ 97

Author(s):

Arne Foldvik ◽

Knut Aagaard ◽

Tor Tørresen

Keyword(s):

Velocity Field ◽

East Greenland ◽

East Greenland Current

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Wind-Driven Coastal Upwelling and Downwelling in the Shelfbreak East Greenland Current

Journal of Geophysical Research Oceans ◽

10.1029/2018jc014273 ◽

2018 ◽

Vol 123 (9) ◽

pp. 6106-6115 ◽

Cited By ~ 1

Author(s):

Lisbeth Håvik ◽

Kjetil Våge

Keyword(s):

Coastal Upwelling ◽

East Greenland ◽

East Greenland Current ◽

Upwelling And Downwelling

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Atlantic-Origin Overflow Water in the East Greenland Current

Journal of Physical Oceanography ◽

10.1175/jpo-d-18-0216.1 ◽

2019 ◽

Vol 49 (9) ◽

pp. 2255-2269 ◽

Cited By ~ 1

Author(s):

Lisbeth Håvik ◽

Mattia Almansi ◽

Kjetil Våge ◽

Thomas W. N. Haine

Keyword(s):

Potential Temperature ◽

Small Degree ◽

Water Masses ◽

East Greenland ◽

Eddy Activity ◽

Deep Circulation ◽

Dense Water ◽

East Greenland Current ◽

Denmark Strait ◽

Atlantic Origin

AbstractDense water masses transported southward along the east coast of Greenland in the East Greenland Current (EGC) form the largest contribution to the Denmark Strait Overflow. When exiting Denmark Strait these dense water masses sink to depth and feed the deep circulation in the North Atlantic. Based on one year of mooring observations upstream of Denmark Strait and historical hydrographic profiles between Fram Strait and Denmark Strait, we find that a large part (75%) of the overflow water ( ≥ 27.8 kg m−3) transported by the EGC is of Atlantic origin (potential temperature θ > 0°C). The along-stream changes in temperature of the Atlantic-origin Water are moderate north of 69°N at the northern end of Blosseville basin, but southward from this point the temperature decreases more rapidly. We hypothesize that this enhanced modification is related to the bifurcation of the EGC taking place close to 69°N into the shelfbreak EGC and the separated EGC. This is associated with enhanced eddy activity and strong water mass modification reducing the intermediate temperature and salinity maxima of the Atlantic-origin Water. During periods with a large (small) degree of modification the separated current is strong (weak). Output from a high-resolution numerical model supports our hypothesis and reveals that large eddy activity is associated with an offshore shift of the surface freshwater layer that characterizes the Greenland shelf. The intensity of the eddy activity regulates the density and the hydrographic properties of the Denmark Strait Overflow Water transported by the EGC system.

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