Circulation phenomena and frontal dynamics of the Norwegian coastal current

1981 ◽  
Vol 302 (1472) ◽  
pp. 635-647 ◽  
Keyword(s):  
Atlantic Water ◽  
Strong Mixing ◽  
Coastal Current ◽  
General Description ◽  
The North ◽  
Dominant Feature ◽  
The North Sea ◽  
Frontal Dynamics ◽  
Norwegian Coastal Current ◽  
Signal Channel

After a short general description of the Norwegian Coastal Current, some recent investigations concerning its variability are reviewed. The variability caused by meteorological effects and fresh water fluxes is shown to be the dominant feature. The coastal current not only responds to local wind-forcing but is also a signal channel of sea-level variations in the North Sea as a whole. The variability at times manifests itself as mesoscale waves and eddies. The subsurface frontal region is characterized by interleaving of coastal and Atlantic water, and strong mixing. Lateral and longitudinal frontal motions are dealt with in relation to plumes of brackish water from the fjords and outbreaks of brackish and/or warm water masses from the Skagerrak. The inflow of Atlantic water through the Norwegian Trench, and the formation of deep and bottom water in Skagerrak are discussed.

The use of Cs and Sr isotopes as tracers in the Arctic Mediterranean Seas

1988 ◽  
Vol 325 (1583) ◽  
pp. 161-176 ◽  
Keyword(s):  
Deep Water ◽  
Thermohaline Circulation ◽  
Atlantic Water ◽  
The Arctic ◽  
Coastal Current ◽  
Intermediate Water ◽  
Sr Isotopes ◽  
Arctic Ice ◽  
Norwegian Coastal Current

The Arctic Mediterranean Seas constitute an oceanic region in which the thermohaline circulation has a strong advective component and deep ventilation processes are very active relative to other oceanic areas. Details of the nature of these circulation and ventilation processes have been revealed through use of Cs and Sr isotopes from bomb-fallout and nuclear-waste sources as ocean tracers. In both cases, their regional input is dominated by advective supply in the Norwegian Atlantic Current and Norwegian Coastal Current, respectively. The different temporal, spatial, and compositional input patterns of these tracers have been used to study different facets of the regional circulation. These input differences and some representative applications of the use of these tracers are reviewed. The data discussed derive from samples collected both from research vessels and from Arctic ice camps. The topics addressed include: ( a ) the role of Arctic Intermediate Water as source, supplying recent surface water to North Atlantic Deep Water via the Denmark Strait overflow; ( b ) deep convective mixing in the Greenland Sea; ( c ) circulation or recirculation of Atlantic water in the Arctic basins; and ( d ) the role of Arctic shelfwaters in the ventilation of intermediate and deep water in the Eurasian and Canadian basins.

scholarly journals A Note on the Water Movements in the English Channel and Neighbouring Seas, considered on the Basis of Salinity Distribution.

1925 ◽  
Vol 13 (3) ◽  
pp. 670-672 ◽  
Author(s):  
J. R. Lumby
Keyword(s):  
Sea Water ◽  
Water Movement ◽  
Atlantic Water ◽  
Irish Sea ◽  
English Channel ◽  
Southern Bight ◽  
The North ◽  
The North Sea ◽  
Normal Water ◽  
The Irish Sea

Comparison of the conceptions which have hitherto been held in regard to the hydrography of the English Channel with those which are offered as a result of the recent activities of the Atlantic Slope Committee, shows that a difference exists which, in the writer's opinion, lies in the interpretation of the material, rather than in the fundamental differences in the material itself. For example, it is stated that the physical character of the water in the English Channel is conditioned, especially in the summer months, by that of the North Sea water rather than by that of the Atlantic water. “En plein été, en août, les eaux chaudes de la mer du Nord affluent dans la Manche.” A similar regimen is suggested for the waters of the Irish Sea, which are said to be derived from the northward. Carruthers shows that the normal water movement in the eastern part of the English Channel is through Dover Straits into the Southern Bight, this movement appearing to be more persistent along the bottom than on the surface. Furthermore, one of the two months in which reversal of this direction appears least likely to occur is August.

scholarly journals The circulation of Icelandic waters – a modelling study

Ocean Science ◽  
2013 ◽  
Vol 9 (5) ◽  
pp. 931-955 ◽  
Author(s):  
K. Logemann ◽  
J. Ólafsson ◽  
Á. Snorrason ◽  
H. Valdimarsson ◽  
G. Marteinsdóttir
Keyword(s):  
Three Dimensional ◽  
Atlantic Water ◽  
Volume Transport ◽  
Ocean Model ◽  
The Arctic ◽  
Coastal Current ◽  
Mean Flow ◽  
Model Code ◽  
The North ◽  
Icelandic Waters

Abstract. The three-dimensional flow, temperature and salinity fields of the North Atlantic, including the Arctic Ocean, covering the time period 1992 to 2006 are simulated with the numerical ocean model CODE. The simulation reveals several new insights and previously unknown structures which help us to clarify open questions on the regional oceanography of Icelandic waters. These relate to the structure and geographical distribution of the coastal current, the primary forcing of the North Icelandic Irminger Current (NIIC) and the path of the Atlantic Water south-east of Iceland. The model's adaptively refined computational mesh has a maximum resolution of 1 km horizontal and 2.5 m vertical in Icelandic waters. CTD profiles from this region and the river discharge of 46 Icelandic watersheds, computed by the hydrological model WaSiM, are assimilated into the simulation. The model realistically reproduces the established elements of the circulation around Iceland. However, analysis of the simulated mean flow field also provides further insights. It suggests a distinct freshwater-induced coastal current that only exists along the south-west and west coasts, which is accompanied by a counter-directed undercurrent. The simulated transport of Atlantic Water over the Icelandic shelf takes place in a symmetrical system of two currents, with the established NIIC over the north-western and northern shelf, and a hitherto unnamed current over the southern and south-eastern shelf, which is simulated to be an upstream precursor of the Faroe Current (FC). Both currents are driven by barotropic pressure gradients induced by a sea level slope across the Greenland–Scotland Ridge. The recently discovered North Icelandic Jet (NIJ) also features in the model predictions and is found to be forced by the baroclinic pressure field of the Arctic Front, to originate east of the Kolbeinsey Ridge and to have a volume transport of around 1.5 Sv within northern Denmark Strait. The simulated multi-annual mean Atlantic Water transport of the NIIC increased by 85% during 1992 to 2006, whereas the corresponding NIJ transport decreased by 27%. Based on our model results we propose a new and further differentiated circulation scheme of Icelandic waters whose details may inspire future observational oceanography studies.

scholarly journals Benthic biomass size spectra in shelf and deep-sea sediments

2014 ◽  
Vol 11 (22) ◽  
pp. 6401-6416 ◽  
Author(s):  
B. A. Kelly-Gerreyn ◽  
A. P. Martin ◽  
B. J. Bett ◽  
T. R. Anderson ◽  
J. I. Kaariainen ◽  
...  
Keyword(s):  
Body Size ◽  
Atlantic Water ◽  
Scaling Exponent ◽  
Metabolic Theory ◽  
Size Spectra ◽  
Size Classes ◽  
The North ◽  
The North Sea ◽  
Wet Weight ◽  
Biomass Spectra

Abstract. The biomass distributions of marine benthic metazoans (meio- to macro-fauna, 1 μg–32 mg wet weight) across three contrasting sites were investigated to test the hypothesis that allometry can consistently explain observed trends in biomass spectra. Biomass (and abundance) size spectra were determined from observations made at the Faroe–Shetland Channel (FSC) in the Northeast Atlantic (water depth 1600 m), the Fladen Ground (FG) in the North Sea (150 m), and the hypoxic Oman Margin (OM) in the Arabian Sea (500 m). Observed biomass increased with body size as a power law at FG (scaling exponent, b = 0.16) and FSC (b = 0.32), but less convincingly at OM (b = 0.12 but not significantly different from 0). A simple model was constructed to represent the same 16 metazoan size classes used for the observed spectra, all reliant on a common detrital food pool, and allowing the three key processes of ingestion, respiration and mortality to scale with body size. A micro-genetic algorithm was used to fit the model to observations at the sites. The model accurately reproduces the observed scaling without needing to include the effects of local influences such as hypoxia. Our results suggest that the size-scaling of mortality and ingestion are dominant factors determining the distribution of biomass across the meio- to macrofaunal size range in contrasting marine sediment communities. Both the observations and the model results are broadly in agreement with the "metabolic theory of ecology" in predicting a quarter power scaling of biomass across geometric body size classes.

scholarly journals The circulation of Icelandic waters – a modelling study

2013 ◽  
Vol 10 (2) ◽  
pp. 763-824 ◽  
Author(s):  
K. Logemann ◽  
J. Ólafsson ◽  
Á. Snorrason ◽  
H. Valdimarsson ◽  
G. Marteinsdóttir
Keyword(s):  
Pressure Field ◽  
Three Dimensional ◽  
Atlantic Water ◽  
Ocean Model ◽  
The Arctic ◽  
Coastal Current ◽  
Mean Flow ◽  
The South ◽  
The North ◽  
Icelandic Waters

Abstract. The three-dimensional flow, temperature and salinity fields of the North Atlantic including the Arctic Ocean covering the time period 1992 to 2006 are simulated with the numerical ocean model CODE. The model reveals several new insights and previously unknown structures which help us to clarify open questions on the regional oceanography of Icelandic waters. These relate to the structure and geographical distribution of the coastal current, the primary forcing of the North Icelandic Irminger Current (NIIC), the path of the Atlantic Water south-east of Iceland and the structure of the North Icelandic Jet (NIJ). The model's adaptively refined computational mesh has a maximum resolution of 1 km horizontal and 2.5 m vertical in Icelandic waters. CTD profiles from this region and the river discharge of 46 Icelandic watersheds, computed by the hydrological model WaSiM, are assimilated into the simulation. The model realistically reproduces the established elements of the circulation around Iceland. However, analysis of the simulated mean flow field also provides further insights. It suggests a distinct freshwater-induced coastal current that only exists along the south-west and west coasts which is accompanied by a counter-directed undercurrent. The simulated transport of Atlantic Water over the Icelandic shelf takes place in a symmetrical system of two currents, with the established NIIC over the north-western and northern shelf, and a current over the southern and south-eastern shelf herein called the South Icelandic Current (SIC). Both currents are driven by topographically induced distortions of the Arctic Front's barotropic pressure field. The SIC is simulated to be an upstream precursor of the Faroe Current (FC). The recently discovered North Icelandic Jet (NIJ) also features in the model predictions and is found to be forced by the baroclinic pressure field of the Arctic Front, to originate east of the Kolbeinsey Ridge and to have a volume transport of around 1.5 Sv within northern Denmark Strait. The simulated multi-annual mean Atlantic Water transport of the NIIC increased by 85% during 1992 to 2006, whereas the corresponding NIJ transport decreased by 27%. Based on our model results we propose a new and further differentiated circulation scheme of Icelandic waters whose details may inspire future observational oceanography studies.

scholarly journals Benthic biomass size spectra in shelf and deep-sea sediments

2014 ◽  
Vol 11 (1) ◽  
pp. 901-942 ◽  
Author(s):  
B. A. Kelly-Gerreyn ◽  
A. P. Martin ◽  
B. J. Bett ◽  
T. R. Anderson ◽  
J. I. Kaariainen ◽  
...  
Keyword(s):  
Body Size ◽  
Atlantic Water ◽  
Scaling Exponent ◽  
Size Spectra ◽  
Size Classes ◽  
North East ◽  
The North ◽  
The North Sea ◽  
Wet Weight ◽  
Biomass Spectra

Abstract. The biomass distributions of marine benthic organisms (meio- to macro-fauna, 1 μg–32 mg wet weight) across three contrasting sites were investigated to test the hypothesis that allometry can consistently explain observed trends in biomass spectra. Biomass (and abundance) size spectra were determined from observations made at the Faroe–Shetland Channel in the north-east Atlantic (water depth 1600 m), the Fladen Ground in the North Sea (150 m), and the hypoxic Oman Margin (500 m) in the Arabian Sea. Observed biomass increased with body size as a power law at FG (scaling exponent, b = 0.16) and FSC (b = 0.32), but less convincingly at OM (b = 0.12 but not significantly different from 0). A simple model was constructed to represent the same 16 metazoan size classes used for the observed spectra, all reliant on a common detrital food pool, and allowing the three key processes of ingestion, respiration and mortality to scale with body size. A micro-genetic algorithm was used to fit the model to observations at the sites. The model accurately reproduces the observed scaling without recourse to including the effects of local influences such as hypoxia. Our results suggest that the size-scaling of mortality and ingestion are dominant factors determining the distribution of biomass across the meio- to macrofaunal size range in contrasting marine sediment communities. Both the observations and the model results are broadly in agreement with the "Metabolic Theory of Ecology" in predicting a quarter power scaling of biomass across geometric body size classes.

scholarly journals The Wind Influence on the Jutland Coastal Current Interpreted on the Basis of som Observations

2000 ◽  
Vol 31 (2) ◽  
pp. 127-148 ◽  
Author(s):  
Flemming Jakobsen
Keyword(s):  
North Sea ◽  
German Bight ◽  
Ekman Transport ◽  
Coastal Current ◽  
The North ◽  
Westerly Winds ◽  
Residual Transport ◽  
The North Sea ◽  
Major River ◽  
Wind Influence

The Jutland Coastal Current (JCC) is a freshwater-influenced coastal current localised in the south-eastern part of the North Sea. Its main sources are the Elbe, the Weser, and the Ems, which run into the German Bight, as well as smaller rivers along the Danish west coast. Tides, buoyancy and wind mainly determine the flow field in the Jutland Coastal Current. The Ekman transport in the North Sea far away from land feeds the coastal current along the Jutland coastline within approximately one Rossby radius of the coastline. In this study the influence of the wind on the Jutland Coastal Current (JCC) is investigated on the basis of measurements of wind, salinity, nitrate and current. The wind determines the spatial extent of the current and only during south-southwesterly winds does the JCC flow into the Skagerrak. The major river discharge into the German Bight in 1995 was followed by a decrease in the salinity outside Hirtshals after only 21-45 days in connection with changing southerly and westerly winds. On the 50-hour time-scale the wind determines the gross and residual transport in the JCC as expected from the Ekman transport, together with minor contributions from the buoyancy and tide. The spatial nitrate distributions clearly indicate an inter-annual variation in the nitrate concentrations and thus influence the transport of nitrate.

Geochronology and palaeoenvironment of marine Quaternary deposits in Denmark: new evidence from northern Jutland

1999 ◽  
Vol 136 (5) ◽  
pp. 561-578 ◽  
Author(s):  
H. P. SEJRUP ◽  
K. L. KNUDSEN
Keyword(s):  
North Sea ◽  
Atlantic Water ◽  
Marine Isotope Stage ◽  
Last Interglacial ◽  
The Holocene ◽  
The North ◽  
Hole Area ◽  
Northwest Europe ◽  
The North Sea ◽  
Late Weichselian

The degree of isoleucine epimerization in the benthic foraminiferal species Elphidium excavatum and Bulimina marginata have been measured in four boreholes, penetrating marine interglacial beds, from northern Jutland. The results of these analyses are compiled with results obtained from other sites in Denmark and the North Sea region, and four aminozones (AZs) have been erected. AZ1 (aIle/Ile < 0.05) include the Late Weichselian and the Holocene part of the record. AZ2 (0.08–0.12) includes samples of last interglacial age. AZ3 (0.14–0.16) includes samples from sites that have been previously correlated with the Holsteinian, and marine isotope stage 7 age for this zone is suggested. An age close to 400±100 ka is assigned to AZ4 (0.21–0.26). AZ4 is recorded in corings at Skagen and Nørre Lyngby, and includes the here defined Skagerrak Interglacial, which is tentatively correlated with marine isotope stage 11.The Skagerrak Interglacial sediments are characterized by boreal lusitanian benthic foraminiferal faunas evidencing strong input of Atlantic water to the North Sea. These faunas are replaced by assemblages indicating cooler conditions at least twice during this period. The sedimentation pattern in northern Jutland during this interglacial seems to be different from the sedimentation regimes in the same area at the classical Eemian sites and during the Holocene, which were characterized by large sediment input from the Jutland Current. This difference may be attributed to a change in the geometry of the sedimentary basin through the later part of the Quaternary, which is a result of repeated periods of intense erosion in the confluence area of the Norwegian Channel ice stream. A strong influx of Atlantic water to the North Sea during stage 11 has been suggested earlier, based on records from the Devil's Hole area. However, the correlation of this event to the classic biostratigraphic based schemes of northwest Europe is still problematic.

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