The thermohaline circulation of the Arctic Ocean and the Greenland Sea

1995 ◽  
Vol 352 (1699) ◽  
pp. 287-299 ◽  
Keyword(s):  
Surface Layer ◽  
Arctic Ocean ◽  
Thermohaline Circulation ◽  
Atlantic Water ◽  
The Arctic ◽  
Greenland Sea ◽  
Deep Circulation ◽  
Low Salinity ◽  
The North ◽  
The Arctic Ocean

The thermohaline circulation of the Arctic Ocean and the Greenland Sea is conditioned by the harsh, high latitude climate and by bathymetry. Warm Atlantic water loses its heat and also becomes less saline by added river run-off. In the Arctic Ocean, this leads to rapid cooling of the surface water and to ice formation. Brine, released by freezing, increases the density of the surface layer, but the ice cover also insulates the ocean and reduces heat loss. This limits density increase, and in the central Arctic Ocean a low salinity surface layer and a permanent ice cover are maintained. Only over the shallow shelves, where the entire water column is cooled to freezing, can dense water form and accumulate to eventually sink down the continental slope into the deep ocean. The part of the Atlantic water which enters the Arctic Ocean is thus separated into a low density surface layer and a denser, deep circulation. These two loops exit through Fram Strait. The waters are partly rehomogenized in the Greenland Sea. The main current is confined to the Greenland continental slope, but polar surface water and ice are injected into the central gyre and create a low density lid, allowing for ice formation in winter. This leads to a density increase sufficient to trigger convection, upwelling and subsequent ice melt. The convection maintains the weak stratification of the gyre and also reinforces the deep circulation loop. As the transformed waters return to the North Atlantic the low-salinity, upper water of the East Greenland Current enters the Labrador Sea and influences the formation of Labrador Sea deep water. The dense loop passes through Denmark Strait and the Faroe-Shetland Channel and sinks to contribute to the North Atlantic deep water. Changes in the forcing conditions might alter the relative strength of the two loops. This could affect the oceanic thermohaline circulation on a global scale

Drivers of sea ice decline in the Fram Strait and north of Svalbard 

2021 ◽  
Author(s):  
Agata Grynczel ◽  
Agnieszka Beszczynska-Moeller ◽  
Waldemar Walczowski
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Ice Cover ◽  
Atlantic Water ◽  
The Arctic ◽  
Fram Strait ◽  
Atmospheric Conditions ◽  
The North ◽  
The Arctic Ocean ◽  
Atlantic Origin

<p>The Arctic Ocean is undergoing rapid change. Satellite observations indicate significant negative Arctic sea ice extent trends in all months and substantial reduction of winter sea ice in the Atlantic sector. One of the possible reasons can be sought in the observed warming of Atlantic water, carried through Fram Strait into the Arctic Ocean. Fram Strait, as well as the region north of Svalbard, play a key role in controlling the amount of oceanic heat supplied to the Arctic Ocean and are the place of dynamic interaction between the ocean and sea ice. Shrinking sea ice cover in the southern part of Nansen Basin (north of Svalbard) and shifting the ice edge in Fram Strait are driven by the interplay between increased advection of oceanic heat in the Atlantic origin water and changes in the local atmospheric conditions.</p><p>Processes related to the loss of sea ice and the upward transport of heat from the layers of the Arctic Ocean occupied by the Atlantic water are still not fully explored, but higher than average temperature of Atlantic inflow in the Nordic Seas influence the upper ocean stratification and ice cover in the Arctic Ocean, in particular in the north of Svalbard area. The regional sea ice cover decline is statistically signifcant in all months, but the largest changes in the Nansen Basin are observed in winter season. The winter sea ice loss north of Svalbard is most pronounced above the core of the inflow warm Atlantic water. The basis for this hypothesis of the research is that continuously shrinking sea ice cover in the region north of Svalbard and withdrawal of the sea ice cover towards the northeast are driven by the interplay between increased oceanic heat in the Atlantic origin water and changes in the local atmospheric conditions, that can result in the increased ocean-air-sea ice exchange in winter seasons. In the current study we describe seasonal, interannual and decadal variability of concentration, drift, and thickness of sea ice in two regions, the north of Svalbard and central part of the Fram Strait, based on the satellite observations. To analyze the observed changes in the sea ice cover in relation to Atlantic water variability and atmospheric forcing we employ hydrographic data from the repeated CTD sections and new atmospheric reanalysis from ERA5. Atlantic water variability is described based on the set of summer synoptic sections across the Fram Strait branch of the Atlantic inflow that have been occupied annually since 1996 under the long-term observational program AREX of the Institute of Oceanology PAS. To elucidate driving mechanisms of the sea ice cover changes observed in different seasons in Fram Strait and north of Svalbard we analyze changes in the temperature, heat content and transport of the Atlantic water and describe their potential links to variable atmospheric forcing, including air temperature, air-ocean fluxes, and changes in wind pattern and wind stress.</p>

scholarly journals The Arctic Ocean as a dead end for floating plastics in the North Atlantic branch of the Thermohaline Circulation

2017 ◽  
Vol 3 (4) ◽  
pp. e1600582 ◽  
Author(s):  
Andrés Cózar ◽  
Elisa Martí ◽  
Carlos M. Duarte ◽  
Juan García-de-Lomas ◽  
Erik van Sebille ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
North Atlantic ◽  
Thermohaline Circulation ◽  
The Arctic ◽  
The North ◽  
Dead End ◽  
The Arctic Ocean ◽  
The North Atlantic

scholarly journals On the Interplay between the Circulation in the Surface and the Intermediate Layers of the Arctic Ocean

2015 ◽  
Vol 45 (5) ◽  
pp. 1393-1409 ◽  
Author(s):  
Camille Lique ◽  
Helen L. Johnson ◽  
Peter E. D. Davis
Keyword(s):  
Surface Layer ◽  
Arctic Ocean ◽  
Time Scales ◽  
Atlantic Water ◽  
Current Strength ◽  
The Arctic ◽  
Ekman Pumping ◽  
Boundary Current ◽  
Layer System ◽  
The Arctic Ocean

AbstractThe circulation of the Arctic Ocean has traditionally been studied as a two-layer system, with a wind-driven anticyclonic gyre in the surface layer and a cyclonic boundary current in the Atlantic Water (AW) layer, primarily forced remotely through inflow and outflow to the basin. Here, an idealized numerical model is used to investigate the interplay between the dynamics of the two layers and to explore the response of the circulation in each of the layers to a change in the forcing in either layer. In the model, the intensity of the circulation in the surface and AW layers is primarily set by the ocean surface stress curl intensity and the inflow to the basin, respectively. Additionally, the surface layer circulation can strongly modulate the intensity of the intermediate layer by constraining the lateral extent of the AW current on the slope. In contrast, a change in the AW current strength has little effect on the surface layer circulation. The intensity of the circulation in the surface layer adjusts over a decade, on a time scale consistent with a balance between Ekman pumping and an eddy-induced volume flux toward the boundary, while the circulation in the AW layer adjusts quickly to any change of forcing (~1 month) through the propagation of boundary-trapped waves. As the two layers have different adjustment processes and time scales, and are subject to forcing that varies on all time scales, the interplay between the dynamics of the two layers is complex, and more simultaneous observations of the circulation within the two layers are required to fully understand it.

Impact of Atlantic water variability on sea ice changes in the Fram Strait and north of Svalbard

2020 ◽  
Author(s):  
Agata Grynczel ◽  
Agnieszka Beszczynska-Moeller ◽  
Waldemar Walczowski
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Ice Cover ◽  
Atlantic Water ◽  
The Arctic ◽  
Fram Strait ◽  
Atlantic Sector ◽  
The North ◽  
The Arctic Ocean ◽  
West Spitsbergen

<p>Recent satellite passive microwave observations indicate significant negative Arctic sea ice extent trends in all months and substantial reduction of winter sea ice in the Atlantic sector. Warm and salty oceanic water masses from the North Atlantic flow towards the Arctic Ocean along the eastern Fram Strait, carried by the West Spitsbergen Current (WSC). Fram Strait, as well as the region north of Svalbard, play a key role in controlling the amount of oceanic heat supplied to the Arctic Ocean and are the place of dynamic interaction between the ocean and sea ice. The north of Svalbard area is one of the regions where the substantial changes in sea ice concentrations are observed both in summer and in winter. One of the possible reasons can be sought in the observed warming of Atlantic water, carried through Fram Strait into the Arctic Ocean. The main goal of this work is to analyse and explain the sea ice variability along main pathways of the Atlantic origin water (AW) in the context of observed warming of Atlantic water layer. Shrinking sea ice cover in the southern part of Nansen Basin (north of Svalbard) and shifting the ice edge in Fram Strait are driven by the interplay between increased advection of oceanic heat in the Atlantic origin water and changes in the local atmospheric conditions that result in the increased ocean-air-sea ice exchange in winter seasons. The basis for this hypothesis is warming of winter mean surface air temperature observed north of Svalbard and withdrawal of the sea ice cover towards the northeast, along with the pathways of water inflow in the Atlantic sector of the Arctic Ocean. Hydrographic data from vertical CTD profiles were collected during annual summer expeditions of the research vessel "Oceania", conducted in Fram Strait and the southern part of the Nansen Basin over the past two decades. The measurement strategy of the original research program AREX, which consists of the performance of cross-sections perpendicular to the presumed direction of the West Spitsbergen Current, allowed to observe changes in the properties and transport of the Atlantic Water carried to the Arctic Ocean. The analysis of past and present changes in the sea ice cover in relation to Atlantic water variability and atmospheric forcing employs hydrographic data from the repeated CTD sections, systematically collected since 1996 during annual summer Arctic long-term monitoring program AREX, satellite products of sea ice concentration and drift, and selected reanalysis data sets.</p>

Zooplankton from the Arctic Ocean and Adjacent Canadian Waters

1965 ◽  
Vol 22 (2) ◽  
pp. 543-564 ◽  
Author(s):  
E. H. Grainger
Keyword(s):  
Surface Layer ◽  
Surface Water ◽  
Arctic Ocean ◽  
Canadian Arctic ◽  
Atlantic Water ◽  
The Arctic ◽  
Central Arctic Ocean ◽  
As Species ◽  
Calanus Glacialis ◽  
The Arctic Ocean

Zooplankton collections from the Arctic Ocean, the Beaufort Sea, and northwestern Canadian coastal waters are described, along with physical characteristics of the waters sampled. About 50 species are included.The collections are compared with records from the central Arctic Ocean and other waters adjacent to the present region. The species are shown to fall into three groups. One is characteristic of the surface water of the Arctic Ocean, one of the Atlantic water and to a lesser extent the deep layer of the surface water of the Arctic Ocean, and one of the shallow peripheral seas of the Arctic Ocean.The surface water group includes eight species which account for more than 95% of the copepod individuals found in the surface layer, and which appear to be the only copepods which breed in the surface layer of the central Arctic Ocean. The same species are the major constituents of the zooplankton found in the waters of the Canadian arctic, from the Arctic Ocean to Davis Strait. The deeper Atlantic species of the Arctic Ocean, more numerous as species but far less numerous as individuals than those of the surface water, occur only very rarely in the surface layers, show no evidence of breeding there, and appear to be almost entirely absent from Canadian archipelago waters inside the shelf. Clear continuity of the Arctic Ocean surface fauna through the waters of the Canadian arctic is shown, along with the almost total exclusion from archipelago waters of the deeper Atlantic fauna. This intrusion of Atlantic species into the waters of arctic Canada appears to be almost entirely restricted to the southeast part of the region, especially Hudson Strait and adjacent waters.Development rates of two copepods in the Arctic Ocean, Microcalanus pygmaeus and Calanus glacialis, are discussed.

scholarly journals Measurement of Arctic sea-ice thickness by submarine 5 years after Scicex

2006 ◽  
Vol 44 ◽  
pp. 200-204 ◽  
Author(s):  
Nicholas E. Hughes ◽  
Peter Wadhams
Keyword(s):  
Arctic Ocean ◽  
Moving Average ◽  
Atlantic Water ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Large Area ◽  
Sea Ice Thickness ◽  
The North ◽  
The Arctic Ocean ◽  
Arctic Sea Ice Thickness

AbstractIn April 2004 the Royal Navy submarine HMS Tireless became the first UK submarine to conduct environmental monitoring in the Arctic Ocean since 1996. As the last US SCICEX (Scientific Ice Expeditions) cruise was in 2000, this has been the only opportunity for a civilian scientist to carry out measurement of ice draft and oceanography over a wide area of the Arctic. This paper presents preliminary results and compares them with similar investigations in the 1970s–90s. The route of Tireless covered a large area of the European sector of the Arctic from 5˚E to 62˚W. Transects were carried out from the marginal ice zone in Fram Strait up to the North Pole and along the 85˚N parallel north of Greenland. As part of work for the European Commission IRIS project, image intensity from the advanced synthetic aperture radar instrument on the European Space Agency’s Envisat satellite has been compared with ice draft from the submarine. The raw data were found to be highly variable, so a moving average was applied, producing a correlation of 0.79. Tireless carried a full oceanographic sensor suite and expendable probes for investigation into changes in the Arctic Ocean. The results from these show further erosion of the Arctic cold halocline layer by advancing Atlantic Water compared to previous climatologies and fieldwork expeditions. Preliminary ice-draft data from 85˚N show deeper ice keels than those encountered by a submarine on the same route in 1987.

scholarly journals The poleward enhanced Arctic Ocean cooling machine in a warming climate

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qi Shu ◽  
Qiang Wang ◽  
Zhenya Song ◽  
Fangli Qiao
Keyword(s):  
Arctic Ocean ◽  
Climate Model ◽  
Barents Sea ◽  
Arctic Basin ◽  
The Arctic ◽  
Cooling Efficiency ◽  
Deep Circulation ◽  
The North ◽  
Warming Climate ◽  
The Arctic Ocean

AbstractAs a cooling machine of the Arctic Ocean, the Barents Sea releases most of the incoming ocean heat originating from the North Atlantic. The related air-sea heat exchange plays a crucial role in both regulating the climate and determining the deep circulation in the Arctic Ocean and beyond. It was reported that the cooling efficiency of this cooling machine has decreased significantly. In this study, we find that the overall cooling efficiency did not really drop: When the cooling efficiency decreased in the southern Barents Sea, it increased in the northern Barents and Kara Seas, indicating that the cooling machine has expanded poleward. According to climate model projections, it is very likely that the cooling machine will continue to expand to the Kara Sea and then to the Arctic Basin in a warming climate. As a result, the Arctic Atlantification will be enhanced and pushed poleward in the future.

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