scholarly journals The East Greenland Current and its contribution to the Denmark Strait overflow

2002 ◽  
Vol 59 (6) ◽  
pp. 1133-1154 ◽  
Author(s):  
B Rudels
Keyword(s):  
East Greenland ◽  
East Greenland Current ◽  
Denmark Strait

scholarly journals Wind forcing of salinity anomalies in the Denmark Strait overflow

Ocean Science ◽  
2011 ◽  
Vol 7 (6) ◽  
pp. 821-834 ◽  
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.

scholarly journals Atlantic-Origin Overflow Water in the East Greenland Current

2019 ◽  
Vol 49 (9) ◽  
pp. 2255-2269 ◽  
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.

scholarly journals Structure and Variability of the Shelfbreak East Greenland Current North of Denmark Strait

2017 ◽  
Vol 47 (10) ◽  
pp. 2631-2646 ◽  
Author(s):  
L. Håvik ◽  
K. Våge ◽  
R. S. Pickart ◽  
B. Harden ◽  
W.-J. von Appen ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Time Scales ◽  
Baroclinic Instability ◽  
Shelf Break ◽  
Eddy Kinetic Energy ◽  
East Greenland ◽  
Modes Of Variability ◽  
East Greenland Current ◽  
Denmark Strait ◽  
Seasonal Signal

AbstractData from a mooring array deployed north of Denmark Strait from September 2011 to August 2012 are used to investigate the structure and variability of the shelfbreak East Greenland Current (EGC). The shelfbreak EGC is a surface-intensified current situated just offshore of the east Greenland shelf break flowing southward through Denmark Strait. This study identified two dominant spatial modes of variability within the current: a pulsing mode and a meandering mode, both of which were most pronounced in fall and winter. A particularly energetic event in November 2011 was related to a reversal of the current for nearly a month. In addition to the seasonal signal, the current was associated with periods of enhanced eddy kinetic energy and increased variability on shorter time scales. The data indicate that the current is, for the most part, barotropically stable but subject to baroclinic instability from September to March. By contrast, in summer the current is mainly confined to the shelf break with decreased eddy kinetic energy and minimal baroclinic conversion. No other region of the Nordic Seas displays higher levels of eddy kinetic energy than the shelfbreak EGC north of Denmark Strait during fall. This appears to be due to the large velocity variability on mesoscale time scales generated by the instabilities. The mesoscale variability documented here may be a source of the variability observed at the Denmark Strait sill.

scholarly journals Some Dynamical Constraints on Upstream Pathways of the Denmark Strait Overflow

2014 ◽  
Vol 44 (12) ◽  
pp. 3033-3053 ◽  
Author(s):  
Jiayan Yang ◽  
Lawrence J. Pratt
Keyword(s):  
Wind Stress ◽  
North Coast ◽  
East Greenland ◽  
Buoyancy Forcing ◽  
Deep Circulation ◽  
The North ◽  
East Greenland Current ◽  
Denmark Strait ◽  
Main Pathway ◽  
Separate Pathway

Abstract The East Greenland Current (EGC) had long been considered the main pathway for the Denmark Strait overflow (DSO). Recent observations, however, indicate that the north Icelandic jet (NIJ), which flows westward along the north coast of Iceland, is a major separate pathway for the DSO. In this study a two-layer numerical model and complementary integral constraints are used to examine various pathways that lead to the DSO and to explore plausible mechanisms for the NIJ’s existence. In these simulations, a westward and NIJ-like current emerges as a robust feature and a main pathway for the Denmark Strait overflow. Its existence can be explained through circulation integrals around advantageous contours. One such constraint spells out the consequences of overflow water as a source of low potential vorticity. A stronger constraint can be added when the outflow occurs through two outlets: it takes the form of a circulation integral around the Iceland–Faroe Ridge. In either case, the direction of overall circulation about the contour can be deduced from the required frictional torques. Some effects of wind stress forcing are also examined. The overall positive curl of the wind forces cyclonic gyres in both layers, enhancing the East Greenland Current. The wind stress forcing weakens but does not eliminate the NIJ. It also modifies the sign of the deep circulation in various subbasins and alters the path by which overflow water is brought to the Faroe Bank Channel, all in ways that bring the idealized model more in line with observations. The sequence of numerical experiments separates the effects of wind and buoyancy forcing and shows how each is important.

Microbial responses to the release of DOC by sea ice and glacier melting in the East Greenland System

2020 ◽  
Author(s):  
Alba Filella Lopez de Lamadrid ◽  
Anja Engel
Keyword(s):  
Ocean Circulation ◽  
Atlantic Water ◽  
The Arctic ◽  
Coastal System ◽  
East Greenland ◽  
East Greenland Current ◽  
Enhanced Production ◽  
Denmark Strait ◽  
Variable Environments ◽  
Microbial Responses

&lt;p&gt;Freshwater discharge around Greenland has more than doubled during the last decade. Understanding the associated physical and biogeochemical impacts in the ocean is of great importance for future predictions of ocean circulation, productivity and feedbacks within the Earth system. In summer 2019 we performed several cross-shore sections passing through the highly variable environments and physical regimes along the east Greenland coastline. Microbial communities showed distinct latitudinal and meridional distributions. Water mass characteristics played a major role in controlling the abundances of organisms with few groups appearing in significant numbers in coastal (colder and fresher) waters. Surface polar waters rich in dissolved organic carbon (DOC) flow south in the East Greenland Current maintaining a high DOC signal in inshore waters. Further optical analyses on the DOC fraction will determine what fractions of this material originate from long scale transport out of the Arctic. Of particular interest was an enhanced production of gel particles rich in carbon in an area extending across Denmark Strait, from close to Scoresby Sund to north of Iceland. Significant concentrations (e.g. 80 &amp;#181;g X.G. eq. L&lt;sup&gt;-1&lt;/sup&gt;) of these transparent exopolymer particles (TEP) were even found deeper than 100m, which is highly unusual. Given the role of TEP as a binding agent for sinking particles, enhancing the sinking of carbon in the water column, it is of interest to know why such a TEP hotspot arises. We hypothesize that it could be either related to circulation through the Strait or the timing of bloom dynamics in this region prior to our cruise. &amp;#160;Our main conclusion from preliminary data analysis is that the east Greenland coastal system is highly dynamic with mixed properties reflecting various degrees of mixing between southward flowing Polar Water and warmer Atlantic water masses.&lt;/p&gt;

Formation of Denmark Strait overflow water by mixing in the East Greenland Current

1993 ◽  
Vol 98 (C4) ◽  
pp. 6907-6919 ◽  
Author(s):  
Volker H. Strass ◽  
Eberhard Fahrbach ◽  
Ursula Schauer ◽  
Lutz Sellmann
Keyword(s):  
East Greenland ◽  
East Greenland Current ◽  
Denmark Strait
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