Deep and intermediate water properties based on Argo floats data in the eastern Nordic Seas

2020 ◽  
Author(s):  
Malgorzata Merchel ◽  
Waldemar Walczowski
Keyword(s):  
Deep Water ◽  
Seasonal Changes ◽  
Global Climate ◽  
The Arctic ◽  
Physical Parameters ◽  
Intermediate Water ◽  
Positive Temperature ◽  
Nordic Seas ◽  
Argo Floats ◽  
The North

<p>The Nordic Seas play an important role in global climate change. Compared with other areas, this region has the largest ocean surface and air positive temperature anomalies in the world. It is particularly important for the water masses formation and modification and for interactions between the ocean and atmosphere. This region is also the main route for freshwater and heat exchange between the North Atlantic and the Arctic Ocean.</p><p>Because the ship-borne measurements are performed usually during the spring to the autumn season, there is no data to analyze seasonal changes in the intermediate and deep water. The Argo floats, operating throughout the whole year, allow observation of seasonal changes that occur in particular regions. This is especially important in the Nordic Seas, where conditions of the oceanographic observations are very difficult even during the summer.</p><p>In this study we analyze hydrographic data collected by the Argo floats in the eastern part of the Nordic Seas region in 2008-2017. Based on the data, both the temporal and spatial variability of the basic physical parameters of the intermediate and deep water were analyzed. It allowed determining how the properties of these waters changed both seasonally and spatially.</p><p><em>The study was funded by the Ministry of Science and Higher Education, Poland under grant agreement No. DIR/WK/2016/12 for the research infrastructure EURO-ARGO ERIC and the National Science Centre, Poland within the DWINS Project (2016/21/N/ST10/02920).</em></p>

Palaeo-oceanography, margin stratigraphy and palaeophysiography of the Tertiary North Atlantic and Norwegian-Greenland seas

1980 ◽  
Vol 294 (1409) ◽  
pp. 177-185 ◽  
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Global Climate ◽  
Circulation Pattern ◽  
The Arctic ◽  
Continental Margins ◽  
Long Distance ◽  
Sea Level Fluctuations ◽  
The North ◽  
Border Zones

The Tertiary was a period of dramatic changes of the palaeo-oceanography of the world’s oceans in general and of the North Atlantic in particular. These changes were caused by (1) the bathymetric evolution of ocean basins and intrabasin pathways (opening of the Norwegian-Greenland Seas and of the pathway to the Arctic Ocean, interruption of the circumglobal equatorial seaway); (2) the geographical development of the oceans and adjacent marginal basins in the context of rapid and intensive eustatic sea level fluctuations; and (3) the deterioration of the global climate throughout the Tertiary (change from a non-glacial to a glacial world, causing major changes in circulation of the surface and deep water). A biostratigraphy of Tertiary sediments deposited close to the continental margins has been developed by using remains of planktonic floras and faunas. Their presence in these sediments and their usefulness for long distance correlations of margin sediments, depend upon the circulation pattern and hydrographic gradients of the oceanic surface and deep water masses, the climatic regime over the continental border zones, and the probability of their post-depositional preservation.

scholarly journals The Atlantic inflow across the Greenland-Scotland ridge in global climate models (CMIP5)

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Céline Heuzé ◽  
Marius Årthun
Keyword(s):  
Heat Transport ◽  
North Atlantic ◽  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
The Arctic ◽  
Nordic Seas ◽  
The North ◽  
The North Atlantic

Oceanic heat transport from the North Atlantic to the Arctic through the Nordic Seas is a key component of the climate system that has to be modelled accurately in order to predict, for example, future Arctic sea ice changes or European climate. Here we quantify biases in the climatological state and dynamics of the transport of oceanic heat into the Nordic Seas across the Greenland-Scotland ridge in 23 state-of-the-art global climate models that participated in the Climate Model Intercomparison Project phase 5. The mean poleward heat transport, its seasonal cycle and interannual variability are inconsistently represented across these models, with a vast majority underestimating them and a few models greatly overestimating them. The main predictor for these biases is the resolution of the model via its representation of the Greenland-Scotland ridge bathymetry: the higher the resolution, the larger the heat transport through the section. The second predictor is the large-scale ocean circulation, which is also connected to the bathymetry: models with the largest heat transport import water from the European slope current into all three straits of the Greenland-Scotland ridge, whereas those with a weak transport import water from the Labrador Sea. The third predictor is the spatial pattern of their main atmospheric modes of variability (North Atlantic Oscillation, East Atlantic and Scandinavian patterns), where the models with a weak inflow have their atmospheric low-pressure centre shifted south towards the central Atlantic. We argue that the key to a better representation of the large-scale oceanic heat transport from the North Atlantic to the Arctic in global models resides not only in higher resolution, but also in a better bathymetry and representation of the complex ocean-ice-atmosphere interactions.

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 North Atlantic deep water formation and AMOC in CMIP5 models

Ocean Science ◽  
2017 ◽  
Vol 13 (4) ◽  
pp. 609-622 ◽  
Author(s):  
Céline Heuzé
Keyword(s):  
Sea Ice ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Deep Water ◽  
Deep Convection ◽  
The Arctic ◽  
Subpolar Gyre ◽  
Deep Water Formation ◽  
Nordic Seas ◽  
Water Formation

Abstract. Deep water formation in climate models is indicative of their ability to simulate future ocean circulation, carbon and heat uptake, and sea level rise. Present-day temperature, salinity, sea ice concentration and ocean transport in the North Atlantic subpolar gyre and Nordic Seas from 23 CMIP5 (Climate Model Intercomparison Project, phase 5) models are compared with observations to assess the biases, causes and consequences of North Atlantic deep convection in models. The majority of models convect too deep, over too large an area, too often and too far south. Deep convection occurs at the sea ice edge and is most realistic in models with accurate sea ice extent, mostly those using the CICE model. Half of the models convect in response to local cooling or salinification of the surface waters; only a third have a dynamic relationship between freshwater coming from the Arctic and deep convection. The models with the most intense deep convection have the warmest deep waters, due to a redistribution of heat through the water column. For the majority of models, the variability of the Atlantic Meridional Overturning Circulation (AMOC) is explained by the volumes of deep water produced in the subpolar gyre and Nordic Seas up to 2 years before. In turn, models with the strongest AMOC have the largest heat export to the Arctic. Understanding the dynamical drivers of deep convection and AMOC in models is hence key to realistically forecasting Arctic oceanic warming and its consequences for the global ocean circulation, cryosphere and marine life.

Influence of Nordic Seas dynamics on the Atlantic Water propagation and its impacts on sea ice concentration.

2021 ◽  
Author(s):  
Sourav Chatterjee ◽  
Roshin P Raj ◽  
Laurent Bertino ◽  
Nuncio Murukesh
Keyword(s):  
Sea Ice ◽  
Deep Water ◽  
Atlantic Water ◽  
The Arctic ◽  
Deep Water Formation ◽  
Sea Ice Concentration ◽  
Nordic Seas ◽  
Ice Concentration ◽  
Water Formation

<p>Enhanced intrusion of warm and saline Atlantic Water (AW) to the Arctic Ocean (AO) in recent years has drawn wide interest of the scientific community owing to its potential role in ‘Arctic Amplification’. Not only the AW has warmed over the last few decades , but its transfer efficiency have also undergone significant modifications due to changes in atmosphere and ocean dynamics at regional to large scales. The Nordic Seas (NS), in this regard, play a vital role as the major exchange of polar and sub-polar waters takes place in this region. Further, the AW and its significant modification on its way to AO via the Nordic Seas has large scale implications on e.g., deep water formation, air-sea heat fluxes. Previous studies have suggested that a change in the sub-polar gyre dynamics in the North Atlantic controls the AW anomalies that enter the NS and eventually end up in the AO. However, the role of NS dynamics in resulting in the modifications of these AW anomalies are not well studied. Here in this study, we show that the Nordic Seas are not only a passive conduit of AW anomalies but the ocean circulations in the Nordic Seas, particularly the Greenland Sea Gyre (GSG) circulation can significantly change the AW characteristics between the entry and exit point of AW in the NS. Further, it is shown that the change in GSG circulation can modify the AW heat distribution in the Nordic Seas and can potentially influence the sea ice concentration therein. Projected enhanced atmospheric forcing in the NS in a warming Arctic scenario and the warming trend of the AW can amplify the role of NS circulation in AW propagation and its impact on sea ice, freshwater budget and deep water formation.</p>

scholarly journals Carbon isotope (δ<sup>13</sup>C) excursions suggest times of major methane release during the last 14 kyr in Fram Strait, the deep-water gateway to the Arctic

2015 ◽  
Vol 11 (4) ◽  
pp. 669-685 ◽  
Author(s):  
C. Consolaro ◽  
T. L. Rasmussen ◽  
G. Panieri ◽  
J. Mienert ◽  
S. Bünz ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Carbon Isotope ◽  
Deep Water ◽  
Planktonic Foraminifera ◽  
Sediment Supply ◽  
The Arctic ◽  
Fram Strait ◽  
The North ◽  
Carbon Isotope Excursion

Abstract. We present results from a sediment core collected from a pockmark field on the Vestnesa Ridge (~ 80° N) in the eastern Fram Strait. This is the only deep-water gateway to the Arctic, and one of the northernmost marine gas hydrate provinces in the world. Eight 14C AMS dates reveal a detailed chronology for the last 14 ka BP. The δ 13C record measured on the benthonic foraminiferal species Cassidulina neoteretis shows two distinct intervals with negative values termed carbon isotope excursion (CIE I and CIE II, respectively). The values were as low as −4.37‰ in CIE I, correlating with the Bølling–Allerød interstadials, and as low as −3.41‰ in CIE II, correlating with the early Holocene. In the Bølling–Allerød interstadials, the planktonic foraminifera also show negative values, probably indicating secondary methane-derived authigenic precipitation affecting the foraminiferal shells. After a cleaning procedure designed to remove authigenic carbonate coatings on benthonic foraminiferal tests from this event, the 13C values are still negative (as low as −2.75‰). The CIE I and CIE II occurred during periods of ocean warming, sea-level rise and increased concentrations of methane (CH4) in the atmosphere. CIEs with similar timing have been reported from other areas in the North Atlantic, suggesting a regional event. The trigger mechanisms for such regional events remain to be determined. We speculate that sea-level rise and seabed loading due to high sediment supply in combination with increased seismic activity as a result of rapid deglaciation may have triggered the escape of significant amounts of methane to the seafloor and the water column above.

scholarly journals Heat transport pathways into the Arctic and their connections to surface air temperatures

2019 ◽  
Vol 19 (6) ◽  
pp. 3927-3937 ◽  
Author(s):  
Daniel Mewes ◽  
Christoph Jacobi
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Large Scale ◽  
The Arctic ◽  
Positive Temperature ◽  
Transport Pathways ◽  
Temperature Anomalies ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

Abstract. Arctic amplification causes the meridional temperature gradient between middle and high latitudes to decrease. Through this decrease the large-scale circulation in the midlatitudes may change and therefore the meridional transport of heat and moisture increases. This in turn may increase Arctic warming even further. To investigate patterns of Arctic temperature, horizontal transports and their changes in time, we analysed ERA-Interim daily winter data of vertically integrated horizontal moist static energy transport using self-organizing maps (SOMs). Three general transport pathways have been identified: the North Atlantic pathway with transport mainly over the northern Atlantic, the North Pacific pathway with transport from the Pacific region, and the Siberian pathway with transport towards the Arctic over the eastern Siberian region. Transports that originate from the North Pacific are connected to negative temperature anomalies over the central Arctic. These North Pacific pathways have been becoming less frequent during the last decades. Patterns with origin of transport in Siberia are found to have no trend and show cold temperature anomalies north of Svalbard. It was found that transport patterns that favour transport through the North Atlantic into the central Arctic are connected to positive temperature anomalies over large regions of the Arctic. These temperature anomalies resemble the warm Arctic–cold continents pattern. Further, it could be shown that transport through the North Atlantic has been becoming more frequent during the last decades.

Diets of four deep-water scaphopod species (Mollusca) in the North Atlantic and the Nordic Seas

2003 ◽  
Vol 142 (6) ◽  
pp. 1103-1112 ◽  
Author(s):  
G. Gudmundsson ◽  
K. Engelstad ◽  
G. Steiner ◽  
J. Svavarsson
Keyword(s):  
North Atlantic ◽  
Deep Water ◽  
Nordic Seas ◽  
The North ◽  
The North Atlantic

scholarly journals The Arctic–Atlantic Thermohaline Circulation*

2013 ◽  
Vol 26 (21) ◽  
pp. 8698-8705 ◽  
Author(s):  
Tor Eldevik ◽  
Jan Even Ø. Nilsen
Keyword(s):  
Degrees Of Freedom ◽  
Thermohaline Circulation ◽  
Global Climate ◽  
Atlantic Water ◽  
The Arctic ◽  
Freshwater Input ◽  
Future Change ◽  
Nordic Seas ◽  
Atlantic Thermohaline Circulation ◽  
Northern Branch

Abstract The Atlantic Ocean's thermohaline circulation is an important modulator of global climate. Its northern branch extends through the Nordic Seas to the cold Arctic, a region that appears to be particularly influenced by climate change. A thermohaline circulation is fundamentally concerned with two degrees of freedom. This is in particular the case for the inflow of warm and saline Atlantic Water through the Nordic Seas toward the Arctic that is balanced by two branches of outflow. The authors present an analytical model, rooted in observations, that constrains the strength and structure of this Arctic–Atlantic thermohaline circulation. It is found, maybe surprisingly, that the strength of Atlantic inflow is relatively insensitive to anomalous freshwater input; it mainly reflects changes in northern heat loss. Freshwater anomalies are predominantly balanced by the inflow's partition into estuarine and overturning circulation with southward polar outflow in the surface and dense overflow at depth, respectively. More quantitatively, the approach presented herein provides a relatively simple framework for making closed and consistent inference on the thermohaline circulation's response to observed or estimated past and future change in the northern seas.

scholarly journals Deep-Water Flow over the Lomonosov Ridge in the Arctic Ocean

2005 ◽  
Vol 35 (8) ◽  
pp. 1489-1493 ◽  
Author(s):  
M-L. Timmermans ◽  
P. Winsor ◽  
J. A. Whitehead
Keyword(s):  
Arctic Ocean ◽  
Deep Water ◽  
Thermohaline Circulation ◽  
Global Climate ◽  
Volume Flow Rate ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Geothermal Heat ◽  
The Arctic Ocean ◽  
Canadian Basin

Abstract The Arctic Ocean likely impacts global climate through its effect on the rate of deep-water formation and the subsequent influence on global thermohaline circulation. Here, the renewal of the deep waters in the isolated Canadian Basin is quanitified. Using hydraulic theory and hydrographic observations, the authors calculate the magnitude of this renewal where circumstances have thus far prevented direct measurements. A volume flow rate of Q = 0.25 ± 0.15 Sv (Sv ≡ 106 m3 s−1) from the Eurasian Basin to the Canadian Basin via a deep gap in the dividing Lomonosov Ridge is estimated. Deep-water renewal time estimates based on this flow are consistent with 14C isolation ages. The flow is sufficiently large that it has a greater impact on the Canadian Basin deep water than either the geothermal heat flux or diffusive fluxes at the deep-water boundaries.

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