Atlantic water north of Svalbard 1899-2018

2020 ◽  
Author(s):  
Marika Marnela ◽  
Frank Nilsen ◽  
Ragnheid Skogseth ◽  
Kjersti Kalhagen
Keyword(s):  
Historical Data ◽  
Saline Water ◽  
Atlantic Water ◽  
The Arctic ◽  
Boundary Current ◽  
Shelf Slope ◽  
Mean Width ◽  
Vertical Location ◽  
The Mean ◽  
West Spitsbergen

<p>As part of the Nansen Legacy project, waters north of Svalbard are studied. The warm and saline Atlantic water, brought northward by the West Spitsbergen Current cools and freshens as it flows eastward along the slope north of Svalbard, bringing heat and salt into the Arctic Ocean. Hydrographic CTD data are available from various cruises and databases, the main source here being the UNIS Hydrographic Database. Changes in the Atlantic water properties and its horizontal and vertical location on the slope and shelf are mapped from decadal averages of historical data from 1899 to 2018. The mean width of the boundary current following the slope eastward is estimated for five cross-shelf/slope sections from the decadal averages. An Atlantification is present from 1996-2005 to 2006-2018 with warmer and more saline water covering a larger area across the slope and reaching further east.</p>

scholarly journals Changes in Atlantic Water circulation patterns and volume transports North of Svalbard over the last 12 years (2008-2020) 

2021 ◽  
Author(s):  
Marylou Athanase ◽  
Christine Provost ◽  
Camila Artana ◽  
Maria Dolores Pérez-Hernández ◽  
Nathalie Sennéchael ◽  
...  
Keyword(s):  
Atlantic Water ◽  
Ocean Model ◽  
The Arctic ◽  
Boundary Current ◽  
Circulation Patterns ◽  
Yermak Plateau ◽  
Transpolar Drift ◽  
Offshore Flow ◽  
West Spitsbergen ◽  
Volume Transports

<p>Atlantic Water (AW) enters the Arctic through Fram Strait as the West Spitsbergen Current (WSC). When reaching the south of Yermak Plateau, the WSC splits into the Svalbard, Yermak Pass and Yermak Branches. Downstream of Yermak Plateau, AW pathways remain unclear and uncertainties persist on how AW branches eventually merge and contribute to the boundary current along the continental slope. We took advantage of the good performance of the 1/12° Mercator Ocean model in the Western Nansen Basin (WNB) to examine the AW circulation and volume transports in the area. The model showed that the circulation changed in 2008-2020. The Yermak Branch strengthened over the northern Yermak Plateau, feeding the Return Yermak Branch along the eastern flank of the Plateau. West of Yermak Plateau, the Transpolar Drift likely shifted westward while AW recirculations progressed further north. Downstream of the Yermak Plateau, an offshore current developed above the 3800 m isobath, fed by waters from the Yermak Plateau tip. East of 18°E, enhanced mesoscale activity from the boundary current injected additional AW basin-ward, further contributing to the offshore circulation. A recurrent anticyclonic circulation in Sofia Deep developed, which also occasionally fed the western part of the offshore flow. The intensification of the circulation coincided with an overall warming in the upper WNB (0-1000 m), consistent with the progression of AW. This regional description of the changing circulation provides a background for the interpretation of upcoming observations.</p>

scholarly journals Characteristics of Chromophoric and Fluorescent Dissolved Organic Matter in the Nordic Seas

2018 ◽  
Author(s):  
Anna Makarewicz ◽  
Piotr Kowalczuk ◽  
Sławomir Sagan ◽  
Mats A. Granskog ◽  
Alexey K. Pavlov ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Sea Ice ◽  
Chlorophyll A ◽  
Saline Water ◽  
Atlantic Water ◽  
Nordic Seas ◽  
Ice Melt ◽  
Fluorescent Dissolved Organic Matter ◽  
West Spitsbergen

Abstract. Optical properties of Chromophoric (CDOM) and Fluorescent Dissolved Organic Matter (FDOM) were characterized in the Nordic Seas including the West Spitsbergen Shelf during June–July of 2013, 2014 and 2015. The CDOM absorption coefficient at 350 nm, aCDOM(350) showed significant interannual variation. In 2013, the highest average aCDOM(350) values (aCDOM = 0.30 ± 0.12 m−1) were observed due to the influence of cold and low–saline water from the Sørkapp Current in the southern part of West Spitsbergen Shelf. In 2014, aCDOM(350) values were significantly lower than in 2013 (av. aCDOM(350) = 0.14 ± 0.06 m−1), which was associated with the dominance of warm and saline Atlantic Water (AW) in the region, while in 2015 intermediate CDOM absorption (av. aCDOM(350) = 0.19 ± 0.05 m−1) was observed. In situ measurement of three FDOM components revealed that protein–like FDOM dominated and concentration of marine and terrestrial humic–like DOM were very low and its distribution were generally vertically homogenous in the upper ocean (0–100 m). Fluorescence of terrestrial and marine humic–like FDOM decreased in surface waters (0–15 m) near the sea–ice edge by dilution of oceanic waters by sea–ice melt water. The vertical distribution of protein–like FDOM was characterized by a prominent sub–surface maximum that matched the subsurface chlorophyll a maximum and was observed all across the study area. The highest protein–like FDOM fluorescence was observed in the Norwegian Sea in the core of warm AW. There was a significant relationship between the protein–like fluorescence and chlorophyll a fluorescence (R2 = 0.65, p 

scholarly journals Frontal structures in the West Spitsbergen Current margins

Ocean Science ◽  
2013 ◽  
Vol 9 (6) ◽  
pp. 957-975 ◽  
Author(s):  
W. Walczowski
Keyword(s):  
Thermohaline Circulation ◽  
Baroclinic Instability ◽  
Atlantic Water ◽  
Transport Processes ◽  
The Arctic ◽  
The West ◽  
Jet Streams ◽  
Nordic Seas ◽  
Western Border ◽  
West Spitsbergen

Abstract. The structures of the hydrographic fronts separating the Atlantic-origin waters from ambient waters in the northern Nordic Seas are discussed. Flows of the western and eastern branches of the West Spitsbergen Current create the Atlantic domain borders and maintain these fronts. This work is based on previous research and on investigations carried out in the project DAMOCLES (Developing Arctic Modelling and Observational Capabilities for Long-term Environmental Studies). Most of the observational data were collected during the R/V Oceania cruises. The main focus of the paper is the western border of the Atlantic domain – the Arctic Front, alongfrontal and transfrontal transports, and the front instability and variability. The alongfrontal baroclinic jet streams were described as a significant source of the Atlantic Water and heat in the Nordic Seas. The baroclinic instability and advection of baroclinic eddies which occurs due to this instability were found to be the main transfrontal transport processes. Most of the Atlantic Water transported by the western branch recirculates west and southward. The eastern branch of the West Spitsbergen Current provides most of the Atlantic Water entering the Arctic Ocean. Both processes are very important for the Arctic and global thermohaline circulation.

Long-term variability of Atlantic water temperature in the Svalbard fjords in conditions of past and recent global warming

2015 ◽  
Vol 5 (2) ◽  
pp. 134-142 ◽  
Author(s):  
Daniil I. Tislenko ◽  
Boris V. Ivanov
Keyword(s):  
Global Warming ◽  
Surface Air Temperature ◽  
Atlantic Water ◽  
The Arctic ◽  
Observation Data ◽  
Polar Regions ◽  
Arctic Amplification ◽  
The West ◽  
West Spitsbergen

Within last decades, the climate of our planet has underwent remarkable changes. The most notable are those called "Arctic amplification." is the changes comprise a decrease in the area of ​​multi-years ice in 2007 and 2012 in polar regions of the Northern hemisphere, accompanied by the temperature rise of intermediate Atlantic waters, increasing surface temperature. In this paper, an analysis of long-term variability of temperature transformed Atlantic waters (TAW) in the fjords of the West-Spitsbergen island (Isfjorden, Grnfjorden, Hornsund and Kongsfjorden) in the first period (1920–1940) and modern (1990–2009) warming in the Arctic is reported. It is shown that the instrumental observation data corresponds to the periods of rise in temperature in the layer of the TAW and surface air temperature (SAT) for the area of ​​the Svalbard.

scholarly journals Frontal structures in the West Spitsbergen Current margins

2013 ◽  
Vol 10 (4) ◽  
pp. 985-1030 ◽  
Author(s):  
W. Walczowski
Keyword(s):  
Thermohaline Circulation ◽  
Baroclinic Instability ◽  
Atlantic Water ◽  
Transport Processes ◽  
The Arctic ◽  
The West ◽  
Western Border ◽  
Hydrographic Fronts ◽  
West Spitsbergen

Abstract. The structures of the hydrographic fronts separating the Atlantic origin waters from ambient waters in the northern Nordic Seas are discussed. Flows of the western and eastern branches of the West Spitsbergen Current create the Atlantic domain borders and maintain these fronts. The work is based on previous research and on investigations in the project DAMOCLES (Developing Arctic Modeling and Observational Capabilities for Long-term Environmental Studies). Most of the observational data were collected during the R/V Oceania cruises. The main focus of the paper is put on the western border of the Atlantic domain – the Arctic Front, along- and transfrontal transports, the front instability and variability. The baroclinic instability and advection of baroclinic eddies which occurs due to this instability were found as the main transfrontal transport processes. Most of the Atlantic Water transported by the western branch recirculates west and southward. The eastern branch of the West Spitsbergen Current provides most of the Atlantic Water entering the Arctic Ocean. Both processes are very important for the Arctic and global Thermohaline Circulation.

scholarly journals Atlantic water flow through the Faroese Channels

Ocean Science ◽  
2017 ◽  
Vol 13 (6) ◽  
pp. 873-888 ◽  
Author(s):  
Bogi Hansen ◽  
Turið Poulsen ◽  
Karin Margretha Húsgarð Larsen ◽  
Hjálmar Hátún ◽  
Svein Østerhus ◽  
...  
Keyword(s):  
Water Flow ◽  
Saline Water ◽  
General Scheme ◽  
Atlantic Water ◽  
Volume Transport ◽  
The Arctic ◽  
Arctic Regions ◽  
Open Questions ◽  
Surface Drifter ◽  
Flow Through

Abstract. Through the Faroese Channels – the collective name for a system of channels linking the Faroe–Shetland Channel, Wyville Thomson Basin, and Faroe Bank Channel – there is a deep flow of cold waters from Arctic regions that exit the system as overflow through the Faroe Bank Channel and across the Wyville Thomson Ridge. The upper layers, in contrast, are dominated by warm, saline water masses from the southwest, termed Atlantic water. In spite of intensive research over more than a century, there are still open questions on the passage of these waters through the system with conflicting views in recent literature. Of special note is the suggestion that there is a flow of Atlantic water from the Faroe–Shetland Channel through the Faroe Bank Channel, which circles the Faroes over the slope region in a clockwise direction. Here, we combine the observational evidence from ship-borne hydrography, moored current measurements, surface drifter tracks, and satellite altimetry to address these questions and propose a general scheme for the Atlantic water flow through this channel system. We find no evidence for a continuous flow of Atlantic water from the Faroe–Shetland Channel to the Faroe Bank Channel over the Faroese slope. Rather, the southwestward-flowing water over the Faroese slope of the Faroe–Shetland Channel is totally recirculated within the combined area of the Faroe–Shetland Channel and Wyville Thomson Basin, except possibly for a small release in the form of eddies. This does not exclude a possible westward flow over the southern tip of the Faroe Shelf, but even including that, we estimate that the average volume transport of a Circum-Faroe Current does not exceed 0.5 Sv (1 Sv  =  106 m3 s−1). Also, there seems to be a persistent flow of Atlantic water from the western part of the Faroe Bank Channel into the Faroe–Shetland Channel that joins the Slope Current over the Scottish slope. These conclusions will affect potential impacts from offshore activities in the region and they imply that recently published observational estimates of the transport of warm water towards the Arctic obtained by different methods are incompatible.

Lagrangian measurements in the West Spitsbergen Current by Argo floats

2021 ◽  
Author(s):  
Waldemar Walczowski ◽  
Agnieszka Beszczyńska-Möller ◽  
Małgorzata Merchel
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Atlantic Water ◽  
Shelf Break ◽  
The Arctic ◽  
Time Data ◽  
The West ◽  
Argo Floats ◽  
The Arctic Ocean ◽  
West Spitsbergen

<p>Almost 4000 operational Argo floats covering the world's ocean provide near-real-time data on its state. The Arctic is less covered than other waters, but observations collected by Argo floats are gaining in importance. By delivering year-round measurements from the water column down to 2000 m (or to the bottom) along float trajectories, they complement and enhance the synoptic data collected during ship campaigns or by fixed moorings. However, oceanographic measurements with autonomous platforms are significantly limited in the Arctic regions by the presence of sea ice.</p><p>Here we present results obtained by Argo floats deployed in 2012-2020 by the Institute of Oceanology Polish Academy of Sciences (IOPAN) during summer campaigns of RV Oceania. In most years, the Argo floats were launched in the eastern branch (core) and in the western branch of the West Spitsbergen Current (WSC) within the Atlantic water inflow towards the Arctic Ocean. Floats deployed in the WSC core drift predominantly northward over the shelf break and upper slope west of Svalbard. After passing Fram Strait the floats usually turn eastward and continue over the northern Svalbard shelf brake, being advected with the Svalbard Branch of the Atlantic inflow into the Arctic Ocean Boundary Current. The easternmost position reached by the IOPAN Argo float was 39.6°E. Ultimately all deployed floats submerge under the sea ice north of Svalbard or farther to the east and die under the ice. Argo floats deployed in the western WSC branch over the underwater ridges, usually recirculate to the west and continue southward with the East Greenland Current. The float WMO 3901851 that drifted to the Labrador Sea, reached the southernmost latitude of 52.5°N and have been working until now for 4.5 years, which is unusual in the Arctic conditions.    </p><p>The measurements collected in the Marginal Ice Zone are particularly interesting for studying the ocean-atmosphere-ice interactions at the boundary between open and ice-covered ocean as well as they can be used for developing the ice avoidance algorithms for the Argo floats and other under ice sensors and platforms. A number of profiles obtained by Argo floats under the sea ice provide unique measurements in the upper ocean layer that is usually inaccessible from other platforms (e.g., moorings). In 2020 several profiles were collected under the ice cover by Argo floats north of Svalbard and transmitted after the float emerged in the polynya. The eastward flow of warm (up to 4° C at 80 m depth) Atlantic water was observed along the float trajectory over the shelf break. Measurements by Argo floats, revealing the dynamics and transformation of the Atlantic water entering the Arctic Ocean, are compared with ship-borne observations collected during the IOPAN long-term observational program AREX and year-round data from IOPAN moorings deployed north of Svalbard under the A-TWAIN and INTAROS projects.</p>

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.

Long-term observations of the strongest inflow branch of warm water to the Arctic Mediterranean

2020 ◽  
Author(s):  
Bogi Hansen ◽  
Karin M. H. Larsen ◽  
Hjálmar Hátún ◽  
Svein Østerhus
Keyword(s):  
Satellite Altimetry ◽  
Saline Water ◽  
Accurate Determination ◽  
Volume Transport ◽  
High Accuracy ◽  
The Arctic ◽  
Boundary Current ◽  
Data Set

<p>Warm and saline water from the North Atlantic enters the Arctic Mediterranean through three gaps. The strongest of these three flows is the inflow between Iceland and Faroes, which is focused into a narrow boundary current north of the Faroes. This boundary current, the Faroe Current, has been observed with regular CTD cruises since 1988 and with moored ADCPs since 1997, as well as satellite altimetry since 1993. Once calibrated by the long-term ADCP measurements, the satellite altimetry is found to yield high-accuracy determination of the velocity field and volume transport down to fixed depth. Due to geostrophic adjustment, satellite altimetry combined with CTD data also allow fairly accurate determination of the depth of the Atlantic layer. From the combined data set, monthly transport time series have been generated for the period Jan 1993 to April 2019. Over the period, the annually averaged volume transport of Atlantic water in the Faroe Current seems to have increased slightly, while the heat transport relative to an outflow temperature of 0°C increased by 13%, significant at the 95% level. The salinity increased from the mid-1990s to around 2010, after which it has decreased, especially after 2016, leading to the lowest salinities in the whole period since 1988. To stay updated on a possible inflow reduction due to reduced thermohaline ventilation caused by this freshening, the future monitoring system of the Faroe Current is planned to be expanded with moored PIES (Pressure Inverted Echo Sounders). An experiment with two PIES in 2017-2019 has documented that these instruments allow high-accuracy monitoring of the depth of the Atlantic layer on the section, which combined with satellite altimetry and CTD observations should give more accurate transport estimates.</p>

scholarly journals On the Circulation of Atlantic Water in the Arctic Ocean

2013 ◽  
Vol 43 (11) ◽  
pp. 2352-2371 ◽  
Author(s):  
Michael A. Spall
Keyword(s):  
Heat Flux ◽  
Numerical Model ◽  
Arctic Ocean ◽  
Surface Heat Flux ◽  
Atlantic Water ◽  
Surface Heat ◽  
The Arctic ◽  
Analytic Model ◽  
Boundary Current ◽  
The Arctic Ocean

Abstract An idealized eddy-resolving numerical model and an analytic three-layer model are used to develop ideas about what controls the circulation of Atlantic Water in the Arctic Ocean. The numerical model is forced with a surface heat flux, uniform winds, and a source of low-salinity water near the surface around the perimeter of an Arctic basin. Despite this idealized configuration, the model is able to reproduce many general aspects of the Arctic Ocean circulation and hydrography, including exchange through Fram Strait, circulation of Atlantic Water, a halocline, ice cover and transport, surface heat flux, and a Beaufort Gyre. The analytic model depends on a nondimensional number, and provides theoretical estimates of the halocline depth, stratification, freshwater content, and baroclinic shear in the boundary current. An empirical relationship between freshwater content and sea surface height allows for a prediction of the transport of Atlantic Water in the cyclonic boundary current. Parameters typical of the Arctic Ocean produce a cyclonic boundary current of Atlantic Water of O(1 − 2 Sv; where 1 Sv ≡ 106 m3 s−1) and a halocline depth of O(200 m), in reasonable agreement with observations. The theory compares well with a series of numerical model calculations in which mixing and environmental parameters are varied, thus lending credibility to the dynamics of the analytic model. In these models, lateral eddy fluxes from the boundary and vertical diffusion in the interior are important drivers of the halocline and the circulation of Atlantic Water in the Arctic Ocean.

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