scholarly journals The East Greenland Current and its impacts on the Nordic Seas: observed trends in the past decade

2012 ◽  
Vol 69 (5) ◽  
pp. 841-851 ◽  
Author(s):  
Bert Rudels ◽  
Meri Korhonen ◽  
Gereon Budéus ◽  
Agnieszka Beszczynska-Möller ◽  
Ursula Schauer ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
The Arctic ◽  
Greenland Sea ◽  
Nordic Seas ◽  
East Greenland ◽  
The Past ◽  
East Greenland Current ◽  
Deep Waters ◽  
The Arctic Ocean

Abstract Rudels, B., Korhonen, M., Budéus, G., Beszczynska-Möller, A., Schauer, U., Nummelin, A., Quadfasel, D., and Valdimarsson, H. 2012. The East Greenland Current and its impacts on the Nordic Seas: observed trends in the past decade. – ICES Journal of Marine Science, 69: 841–851. For the past 30 years, it has been known that dense waters are created in the Arctic Ocean. However, before the late 1980s, observations indicated that Arctic Ocean deep waters only modified the deep water in the Greenland Sea, which was still thought of as the major source of dense water. In the mid-1990s, this picture began to fade. The deep convection in the Greenland Sea weakened and only Arctic Intermediate Water was formed. A deep salinity maximum was reinforced and a temperature maximum emerged at mid-depth. The densities of the salinity and temperature maxima were those of the deep waters in the Arctic Ocean, and one possibility was that waters below the convection were ventilated by Arctic Ocean deep waters from the East Greenland Current. Between 1998 and 2010, the salinity and temperature of the deep water in the Greenland Sea increased, implying continuous input from the East Greenland Current. Water from the Greenland Sea advected to Fram Strait now has almost Arctic Ocean characteristics and cannot significantly change the outflowing Arctic Ocean waters by mixing in the East Greenland Current, leading to a more-rapid transformation of the deep Greenland Sea water column.

scholarly journals Water-mass formation and distribution in the Nordic Seas during the 1990s

2004 ◽  
Vol 61 (5) ◽  
pp. 846-863 ◽  
Author(s):  
Johan Blindheim ◽  
Francisco Rey
Keyword(s):  
Arctic Ocean ◽  
Oxygen Content ◽  
Deep Water ◽  
The Arctic ◽  
Central Basin ◽  
Greenland Sea ◽  
Nordic Seas ◽  
Norwegian Sea ◽  
Deep Waters ◽  
Salinity Increase

Abstract Hydrographic, oxygen and nutrient data collected in the Nordic Seas during the 1990s are presented. During the decade, deep waters originating from the Arctic Ocean, identified by salinities in excess of 34.9, spread into the Greenland Basin. In 1991, these waters extended westward from the mid-ocean ridge to about 2°E. This process continued over time and by 1993 there was a layer with salinities above 34.9 along the entire section, between 7.6°W and the Barents Sea Slope, and probably across the whole basin. In 2000 the basin had these high salinities at depths greater than 1400 m. At 1500 m in the central basin the salinity increase during the decade was 0.012 units, decreasing to 0.006 at 3000 m, and associated temperatures increased by 0.28 and 0.09°C, respectively. This warming more than compensated for the salinity increase so that the density of the deep water decreased during the decade, σ3 decreasing by 0.027 kg m−3 at 1500 m and by 0.006 kg m−3 at 3000 m. Decreasing oxygen content and increasing concentrations of silicate further indicated the increasing influence of Arctic Ocean Deep Water. Interaction with the atmosphere is decisive for the conditions in the area. In the central Greenland Sea there is close correlation between wind forcing and upper-layer salinity. Significant deep-water formation occurs only during cold winters, or rather, in periods with several succeeding cold winters and the 1960s were the first period in which these conditions occurred since 1920. This is shown by meteorological observations at Jan Mayen since 1921, and at Stykkisholmur, Iceland, since 1823. Relatively high salinities were observed near the bottom over the Iceland Plateau. These waters seem to be derived from Arctic Ocean deep waters that have been diverted from the East Greenland Current, into the East Icelandic Current. While flowing through the Iceland Sea their nutrient concentration increases considerably. This water flows into the Norwegian Basin where it forms a slight salinity maximum around 1500 m, which is associated with a minimum in oxygen content. At greater depths the water masses are from the Greenland Sea. The salinity decreases and the oxygen increases toward approximately 2500 m, from where the trends are reversed toward a slight salinity maximum around 3000 m, where there also is a minimum in oxygen as well as in CFC-11. These characteristics seem to derive from Arctic Ocean Deep Water, floating above waters more characterized by Greenland Sea Bottom water nearest to the bottom as suggested by decreasing salinity and an increase in both oxygen and CFC-11 concentration. This shows that even the very homogeneous Norwegian Sea Deep Water is stratified. There are also slight differences between the deep waters of the basins in the Norwegian Sea. In the Norwegian Basin the deep water has slightly higher salinity, lower dissolved oxygen and higher silicates than the deep water in the Lofoten Basin, and even more so compared with the area west of Bear Island. This shows that the Lofoten Basin and the northern Norwegian Sea are more directly influenced by waters from the Greenland Sea than the Norwegian Basin.

scholarly journals Does the East Greenland Current exist in the northern Fram Strait?

Ocean Science ◽  
2018 ◽  
Vol 14 (5) ◽  
pp. 1147-1165 ◽  
Author(s):  
Maren Elisabeth Richter ◽  
Wilken-Jon von Appen ◽  
Claudia Wekerle
Keyword(s):  
Arctic Ocean ◽  
Atlantic Water ◽  
Shelf Break ◽  
The Arctic ◽  
Current Loop ◽  
Fram Strait ◽  
Boundary Current ◽  
East Greenland ◽  
East Greenland Current ◽  
The Arctic Ocean

Abstract. Warm Atlantic Water (AW) flows around the Nordic Seas in a cyclonic boundary current loop. Some AW enters the Arctic Ocean where it is transformed to Arctic Atlantic Water (AAW) before exiting through the Fram Strait. There the AAW is joined by recirculating AW. Here we present the first summer synoptic study targeted at resolving this confluence in the Fram Strait which forms the East Greenland Current (EGC). Absolute geostrophic velocities and hydrography from observations in 2016, including four sections crossing the east Greenland shelf break, are compared to output from an eddy-resolving configuration of the sea ice–ocean model FESOM. Far offshore (120 km at 80.8∘ N) AW warmer than 2 ∘C is found in the northern Fram Strait. The Arctic Ocean outflow there is broad and barotropic, but gets narrower and more baroclinic toward the south as recirculating AW increases the cross-shelf-break density gradient. This barotropic to baroclinic transition appears to form the well-known EGC boundary current flowing along the shelf break farther south where it has been previously described. In this realization, between 80.2 and 76.5∘ N, the southward transport along the east Greenland shelf break increases from roughly 1 Sv to about 4 Sv and the proportion of AW to AAW also increases fourfold from 19±8 % to 80±3 %. Consequently, in the southern Fram Strait, AW can propagate into the Norske Trough on the east Greenland shelf and reach the large marine-terminating glaciers there. High instantaneous variability observed in both the synoptic data and the model output is attributed to eddies, the representation of which is crucial as they mediate the westward transport of AW in the recirculation and thus structure the confluence forming the EGC.

scholarly journals New Constraints on the Physical and Biological Controls on the Silicon Isotopic Composition of the Arctic Ocean

2021 ◽  
Vol 8 ◽  
Author(s):  
Mark A. Brzezinski ◽  
Ivia Closset ◽  
Janice L. Jones ◽  
Gregory F. de Souza ◽  
Colin Maden
Keyword(s):  
Isotopic Composition ◽  
Arctic Ocean ◽  
Silicic Acid ◽  
Deep Water ◽  
Canada Basin ◽  
The Arctic ◽  
Silicon Isotope ◽  
Deep Waters ◽  
The Arctic Ocean ◽  
Source Waters

The silicon isotope composition of silicic acid, δ30Si(OH)4, in the deep Arctic Ocean is anomalously heavy compared to all other deep ocean basins. To further evaluate the mechanisms leading to this condition, δ30Si(OH)4 was examined on US GEOTRACES section GN01 from the Bering Strait to the North Pole. Isotope values in the polar mixed layer showed a strong influence of the transpolar drift. Drift waters contained relatively high [Si(OH)4] with heavy δ30Si(OH)4 consistent with the high silicate of riverine source waters and strong biological Si(OH)4 consumption on the Eurasian shelves. The maximum in silicic acid concentration, [Si(OH)4], within the double halocline of the Canada Basin formed a local minimum in δ30Si(OH)4 that extended across the Canada Basin, reflecting the high-[Si(OH)4] Pacific source waters and benthic inputs of Si(OH)4 in the Chukchi Sea. δ30Si(OH)4 became lighter with the increase in [Si(OH)4] in intermediate and deep waters; however, both Canada Basin deep water and Eurasian Basin deep water were heavier than deep waters from other ocean basins. A preliminary isotope budget incorporating all available Arctic δ30Si(OH)4 data confirms the importance of isotopically heavy inflows in creating the anomalous deep Arctic Si isotope signature, but also reveals a surprising similarity in the isotopic composition of the major inflows compared to outflows across the main gateways connecting the Arctic with the Pacific and the Atlantic. This similarity implies a major role of biological productivity and opal burial in removing light isotopes entering the Arctic Ocean from rivers.

scholarly journals Does the East Greenland Current exist in northern Fram Strait?

2018 ◽  
Author(s):  
Maren Elisabeth Richter ◽  
Wilken-Jon von Appen ◽  
Claudia Wekerle
Keyword(s):  
Arctic Ocean ◽  
Atlantic Water ◽  
Ocean Model ◽  
The Arctic ◽  
Current Loop ◽  
Fram Strait ◽  
Boundary Current ◽  
East Greenland ◽  
East Greenland Current ◽  
The Arctic Ocean

Abstract. Warm Atlantic Water (AW) flows around the Nordic Seas in a cyclonic boundary current loop. Some AW enters the Arctic Ocean where it is transformed to Arctic Atlantic Water (AAW) before exiting through Fram Strait. There the AAW is joined by recirculating AW. Here we present the first summer synoptic study targeted at resolving this confluence in Fram Strait which forms the East Greenland Current (EGC). Absolute geostrophic velocities and hydrography from observations in 2016, including four sections crossing the east Greenland shelfbreak, are compared to output from an eddy-resolving configuration of the sea–ice ocean model FESOM. Far offshore (120 km at 80.8° N) AW warmer than 2 °C is found in northern Fram Strait. The Arctic Ocean outflow there is broad and barotropic, but gets narrower and more baroclinic toward the south as recirculating AW increases the cross-shelfbreak density gradient. This barotropic to baroclinic transition appears to form the well-known EGC boundary current flowing along the shelfbreak further south where it has been previously described. In this realization, between 80.2° N and 76.5° N, the southward transport along the east Greenland shelfbreak increases from roughly 1 Sv to about 4 Sv and the warm water composition, defined as the fraction of AW of the sum of AW and AAW (AW/(AW + AAW)), changes from 19 ± 8 % to 80 ± 3 %. Consequently, in southern Fram Strait, AW can propagate into Norske Trough on the east Greenland shelf and reach the large marine terminating glaciers there. High instantaneous variability observed in both the synoptic data and the model output is attributed to eddies, the representation of which is crucial as they mediate the westward transport of AW in the recirculation and thus structure the confluence forming the EGC.

scholarly journals On the 14C and 39Ar Distribution in the Central Arctic Ocean: Implications for Deep Water Formation

Radiocarbon ◽  
1994 ◽  
Vol 36 (3) ◽  
pp. 327-343 ◽  
Author(s):  
Peter Schlosser ◽  
Bernd Kromer ◽  
Gote Östlund ◽  
Brenda Ekwurzel ◽  
Gerhard Bönisch ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
Atlantic Water ◽  
The Arctic ◽  
Central Arctic Ocean ◽  
Deep Waters ◽  
The Arctic Ocean ◽  
Bottom Waters ◽  
Eurasian Basin ◽  
Canadian Basin

We present ΔA14C and 39Ar data collected in the Nansen, Amundsen and Makarov basins during two expeditions to the central Arctic Ocean (RV Polarstern cruises ARK IV/3, 1987 and ARK VIII/3, 1991). The data are used, together with published Δ14C values, to describe the distribution of Δ14C in all major basins of the Arctic Ocean (Nansen, Amundsen, Makarov and Canada Basins), as well as the 39Ar distribution in the Nansen Basin and the deep waters of the Amundsen and Makarov Basins. From the combined Δ14C and 39Ar distributions, we derive information on the mean “isolation ages” of the deep and bottom waters of the Arctic Ocean. The data point toward mean ages of the bottom waters in the Eurasian Basin (Nansen and Amundsen Basins) of ca. 250-300 yr. The deep waters of the Amundsen Basin show slightly higher 3H concentrations than those in the Nansen Basin, indicating the addition of a higher fraction of water that has been at the sea surface during the past few decades. Correction for the bomb 14C added to the deep waters along with bomb 3H yields isolation ages for the bulk of the deep and bottom waters of the Amundsen Basin similar to those estimated for the Nansen Basin. This finding agrees well with the 39Ar data. Deep and bottom waters in the Canadian Basin (Makarov and Canada Basins) are very homogeneous, with an isolation age of ca. 450 yr. Δ14C and 39Ar data and a simple inverse model treating the Canadian Basin Deep Water (CBDW) as one well-mixed reservoir renewed by a mixture of Atlantic Water (29%), Eurasian Basin Deep Water (69%) and brine-enriched shelf water (2%) yield a mean residence time of CBDW of ca. 300 yr.

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