scholarly journals Seasonal and Mesoscale Variability of the Two Atlantic Water Recirculation Pathways in Fram Strait

2021 ◽  
Author(s):  
Zerlina Hofmann ◽  
Wilken‐Jon Appen ◽  
Claudia Wekerle
Keyword(s):  
Atlantic Water ◽  
Fram Strait ◽  
Mesoscale Variability ◽  
Water Recirculation

scholarly journals Seasonal and Mesoscale Variability of the Two Atlantic Water Recirculation Pathways in Fram Strait

2021 ◽  
Author(s):  
Zerlina Hofmann ◽  
Wilken-Jon von Appen ◽  
Claudia Wekerle
Keyword(s):  
Sea Ice ◽  
Atlantic Water ◽  
The Arctic ◽  
Fram Strait ◽  
Mesoscale Variability ◽  
The West ◽  
East Greenland Current ◽  
Prime Meridian ◽  
Set Up ◽  
West Spitsbergen

<p>Atlantic Water, which is transported northward by the West Spitsbergen Current, partly recirculates (i.e. turns westward) in Fram Strait. This determines how much heat and salt reaches the Arctic Ocean, and how much joins the East Greenland Current on its southward path. We describe the Atlantic Water recirculation's location, seasonality, and mesoscale variability by analyzing the first observations from moored instruments at five latitudes in central Fram Strait, spanning a period from August 2016 to July 2018. We observe recirculation on the prime meridian at 78°50'N and 80°10'N, respectively south and north of the Molly Hole, and no recirculation further south at 78°10'N and further north at 80°50'N. At a fifth mooring location at 79°30'N, we observe some influence of the two recirculation branches. The southern recirculation is observed as a continuous westward flow that carries Atlantic Water throughout the year, though it may be subject to broadening and narrowing. It is affected by eddies in spring, likely due to the seasonality of mesoscale instability in the West Spitsbergen Current. The northern recirculation is observed solely as passing eddies on the prime meridian, which are strongest during late autumn and winter, and absent during summer. This seasonality is likely affected both by the conditions set by the West Spitsbergen Current and by the sea ice. Open ocean eddies originating from the West Spitsbergen Current interact with the sea ice edge when they subduct below the fresher, colder water. Additionally the stratification set up by sea ice presence may inhibit recirculation.</p>

scholarly journals Eddy‐driven recirculation of Atlantic Water in Fram Strait

2016 ◽  
Vol 43 (7) ◽  
pp. 3406-3414 ◽  
Author(s):  
Tore Hattermann ◽  
Pål Erik Isachsen ◽  
Wilken‐Jon Appen ◽  
Jon Albretsen ◽  
Arild Sundfjord
Keyword(s):  
Atlantic Water ◽  
Fram Strait

scholarly journals Intensification of the Atlantic Water Supply to the Arctic Ocean Through Fram Strait Induced by Arctic Sea Ice Decline

2020 ◽  
Vol 47 (3) ◽  
Author(s):  
Qiang Wang ◽  
Claudia Wekerle ◽  
Xuezhu Wang ◽  
Sergey Danilov ◽  
Nikolay Koldunov ◽  
...  
Keyword(s):  
Sea Ice ◽  
Water Supply ◽  
Arctic Ocean ◽  
Atlantic Water ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Fram Strait ◽  
Sea Ice Decline ◽  
Arctic Sea ◽  
The Arctic Ocean

scholarly journals Circulation and transformation of Atlantic water in the Eurasian Basin and the contribution of the Fram Strait inflow branch to the Arctic Ocean heat budget

2015 ◽  
Vol 132 ◽  
pp. 128-152 ◽  
Author(s):  
Bert Rudels ◽  
Meri Korhonen ◽  
Ursula Schauer ◽  
Sergey Pisarev ◽  
Benjamin Rabe ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Heat Budget ◽  
Atlantic Water ◽  
The Arctic ◽  
Fram Strait ◽  
The Arctic Ocean ◽  
Eurasian Basin

scholarly journals Enhanced 20th-century heat transfer to the Arctic simulated in the context of climate variations over the last millennium

2014 ◽  
Vol 10 (6) ◽  
pp. 2201-2213 ◽  
Author(s):  
J. H. Jungclaus ◽  
K. Lohmann ◽  
D. Zanchettin
Keyword(s):  
Heat Transfer ◽  
20Th Century ◽  
Ocean Circulation ◽  
Internal Variability ◽  
Atlantic Water ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Driving Mechanism ◽  
Last Millennium ◽  
Fram Strait

Abstract. Oceanic heat transport variations, carried by the northward-flowing Atlantic Water, strongly influence Arctic sea-ice distribution, ocean–atmosphere exchanges, and pan-Arctic temperatures. Palaeoceanographic reconstructions from marine sediments near Fram Strait have documented a dramatic increase in Atlantic Water temperatures over the 20th century, unprecedented in the last millennium. Here we present results from Earth system model simulations that reproduce and explain the reconstructed exceptional Atlantic Water warming in Fram Strait in the 20th century in the context of natural variability during the last millennium. The associated increase in ocean heat transfer to the Arctic can be traced back to changes in the ocean circulation in the subpolar North Atlantic. An interplay between a weakening overturning circulation and a strengthening subpolar gyre as a consequence of 20th-century global warming is identified as the driving mechanism for the pronounced warming along the Atlantic Water path toward the Arctic. Simulations covering the late Holocene provide a reference frame that allows us to conclude that the changes during the last century are unprecedented in the last 1150 years and that they cannot be explained by internal variability or natural forcing alone.

A satellite-based Lagrangian perspective on Atlantic Water fractionation in the Nordic Seas

2020 ◽  
Author(s):  
Léon Chafik ◽  
Sara Broomé
Keyword(s):  
Arctic Ocean ◽  
Barents Sea ◽  
Bottom Topography ◽  
Atlantic Water ◽  
The Arctic ◽  
Fram Strait ◽  
Nordic Seas ◽  
The Barents Sea ◽  
The Arctic Ocean ◽  
Outer Branch

<p>The Arctic Ocean has been receiving more of the warm and saline Atlantic Water in the past decades. This water mass enters the Arctic Ocean via two Arctic gateways: the Barents Sea Opening and the Fram Strait. Here, we focus on the fractionation of Atlantic Water at these two gateways using a Lagrangian approach based on satellite-derived geostrophic velocities. Simulated particles are released at 70N at the inner and outer branch of the North Atlantic current system in the Nordic Seas. The trajectories toward the Fram Strait and Barents Sea Opening are found to be largely steered by the bottom topography and there is an indication of an anti-phase relationship in the number of particles reaching the gateways. There is, however, a significant cross-over of particles from the outer branch to the inner branch and into the Barents Sea, which is found to be related to high eddy kinetic energy between the branches. This cross-over may be important for Arctic climate variability.</p>

Role of Greenland Sea Gyre Circulation on Atlantic Water Temperature Variability in the Fram Strait

2018 ◽  
Vol 45 (16) ◽  
pp. 8399-8406 ◽  
Author(s):  
Sourav Chatterjee ◽  
Roshin P. Raj ◽  
L. Bertino ◽  
Ø. Skagseth ◽  
M. Ravichandran ◽  
...  
Keyword(s):  
Water Temperature ◽  
Atlantic Water ◽  
Temperature Variability ◽  
Fram Strait ◽  
Greenland Sea ◽  
Gyre Circulation

scholarly journals Circulation timescales of Atlantic Water in the Arctic Ocean determined from anthropogenic radionuclides

Ocean Science ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 111-129
Author(s):  
Anne-Marie Wefing ◽  
Núria Casacuberta ◽  
Marcus Christl ◽  
Nicolas Gruber ◽  
John N. Smith
Keyword(s):  
Arctic Ocean ◽  
Atlantic Water ◽  
Ocean Basin ◽  
The Arctic ◽  
Fram Strait ◽  
Anthropogenic Radionuclides ◽  
East Greenland Current ◽  
The Arctic Ocean ◽  
Lateral Mixing ◽  
Binary Mixing

Abstract. The inflow of Atlantic Water to the Arctic Ocean is a crucial determinant for the future trajectory of this ocean basin with regard to warming, loss of sea ice, and ocean acidification. Yet many details of the fate and circulation of these waters within the Arctic remain unclear. Here, we use the two long-lived anthropogenic radionuclides 129I and 236U together with two age models to constrain the pathways and circulation times of Atlantic Water in the surface (10–35 m depth) and in the mid-depth Atlantic layer (250–800 m depth). We thereby benefit from the unique time-dependent tagging of Atlantic Water by these two isotopes. In the surface layer, a binary mixing model yields tracer ages of Atlantic Water between 9–16 years in the Amundsen Basin, 12–17 years in the Fram Strait (East Greenland Current), and up to 20 years in the Canada Basin, reflecting the pathways of Atlantic Water through the Arctic and their exiting through the Fram Strait. In the mid-depth Atlantic layer (250–800 m), the transit time distribution (TTD) model yields mean ages in the central Arctic ranging between 15 and 55 years, while the mode ages representing the most probable ages of the TTD range between 3 and 30 years. The estimated mean ages are overall in good agreement with previous studies using artificial radionuclides or ventilation tracers. Although we find the overall flow to be dominated by advection, the shift in the mode age towards a younger age compared to the mean age also reflects the presence of a substantial amount of lateral mixing. For applications interested in how fast signals are transported into the Arctic's interior, the mode age appears to be a suitable measure. The short mode ages obtained in this study suggest that changes in the properties of Atlantic Water will quickly spread through the Arctic Ocean and can lead to relatively rapid changes throughout the upper water column in future years.

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 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.

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