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Jan Inge Faleide - One of the best experts on this subject based on the ideXlab platform.
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Northerns Barents Sea evolution linked to the Arctic Ocean
2020Co-Authors: Alexander Minakov, Jan Inge Faleide, Rolf Mjelde, Ritske S. Huismans, Anke Dannowski, Ernst R. Flueh, V. Glebovsky, Henk Keers, Y. Y. PodladchikovAbstract:The current effort represents a systematic regional study of the vast and poorly sampled area, linking the Barents Sea and the Arctic Ocean. The deep structure of the Northern Barents Sea was examined by means of integration various geophysical techniques, including numerical geodynamic modeling. Ocean Bottom Seismometers data have been acquired east of Svalbard and processed using a seismic refraction/reflection tomography method. A series of crustal-scale geotransects, illustrating the architecture of the Cenozoic Northern Barents Sea margin were constructed using gravity modeling, sparse seismic reflection profiles and depth to magnetic sources estimates. The structure of the Mesozoic passive margin, facing to the Amerasia Basin, was inferred based on a similar technique, involving plate reconstructions. Numerical simulations of the lithosphere extension, leading to formation of the Eurasia Basin, was performed using the finite element method. The velocity structure east of Svalbard exhibits evidences of Cretaceous magmatism. In particular, funnel-shaped high-velocity anomalies, reaching 10% relative to the 1D background model, are interpreted as Early Cretaceous magmatic intrusions. Further to the north, a narrow and steep continent-ocean transition was observed. The conjugate northern (and eastern) Barents Sea - Lomonosov Ridge margins are symmetric and narrow whereas the continent-ocean transition on the Podvodnikov Basin's side of the Lomonosov Ridge is broad. On the continental side, the Northern Barents Sea margin is underlain by Paleozoic-Early Mesozoic deep sedimentary basins separated from the oceanic side by the marginal basement uplift. The Northern Barents Sea, including Svalbard, was not affected by the major Late Jurassic - Early Cretaceous rifting which gave rise to deep basins in the South Western Barents Sea. However, the area experienced widespread Early Cretaceous magmatism. The emplacement of mafic magmas was controlled by Paleozoic rift structures which were reactivated in the Early Cretaceous. The magmatism east of Svalbard developed without significant crustal thinning, but was probably triggered by localized lithospheric weakness zones. The Mesozoic passive margin, originated due to the opening of the Podvodnikov Basin, was subjected to significant crustal thinning. The Northern Barents Sea region together with the Lomonosov Ridge was standing high during most of the Late Cretaceous. The regional uplift sourced from the Alpha Ridge area. The Eurasia Basin's breakup in the Paleocene preceded the opening of the Norwegian Sea, implying a connection to the Labrador Sea. A short-lived lithosphere-scale shear zone has likely facilitated to the detachment of the Lomonosov Ridge microcontinent and onset of Seafloor spreading. Shear heating in the mantle lithosphere accompanied the development of the proposed shear zone and served as a mechanism for strain localization.
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Lithospheric strength and elastic thickness of the Barents Sea and Kara Sea region
Tectonophysics, 2016Co-Authors: Sébastien Gac, Peter Klitzke, Alexander Minakov, Jan Inge Faleide, Magdalena Scheck-wenderothAbstract:Interpretation of tomography data indicates that the Barents Sea region has an asymmetric lithospheric structure characterized by a thin and hot lithosphere in the west and a thick and cold lithosphere in the east. This suggests that the lithosphere is stronger in the east than in the west. This asymmetric lithosphere strength structure may have a strong control on the lithosphere response to tectonic and surface processes. In this paper, we present computed strength and effective elastic thickness maps of the lithosphere of the Barents Sea and Kara Sea region. Those are estimated using physical parameters from a 3D lithospheric model of the Barents Sea and Kara Sea region. The lithospheric strength is computed assuming a temperature-dependent ductile and brittle rheology for sediments, crust and mantle lithosphere. Results show that lithospheric strength and elastic thickness are mostly controlled by the lithosphere thickness. The model generally predicts much larger lithospheric strength and elastic thickness for the Proterozoic parts of the East Barents Sea and Kara Sea. Locally, the thickness and lithology of the continental crust disturb this general trend. At last, the gravitational potential energy (GPE) is computed. Our results show that the difference in GPE between the Barents Sea and the Mid-Atlantic Ridge provides a net horizontal force large enough to cause contraction in the western and central Barents Sea.
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the crust and mantle lithosphere in the Barents Sea kara Sea region
Tectonophysics, 2009Co-Authors: O. Ritzmann, Jan Inge FaleideAbstract:Abstract The focus of this study is the nature of a prominent, high-velocity (S-wave) anomaly in the upper mantle below the Barents Sea–Kara Sea region and its relation to the evolution of the sedimentary basins, in particular the Permo–Triassic East Barents Sea Basin. The high-velocity anomaly exhibits a thickness of 75–100 km below the central Barents Sea and thickens considerably below the East Barents Sea Basin (150 km). The thickest part of the high-velocity anomaly follows the outline of the East Barents Sea Basin which is bended around Pai-Khoi–Novaya Zemlya Fold Belt. Density modeling of the lithosphere along a 3200 km long transect from the Barents Sea to the West Siberian Basin was used to evaluate different models for the upper mantle structure. The best fit gravity model was achieved when either assuming a 1D, horizontally- layered mantle structure, or, a forward-modeled density structure using an average Proterozoic mantle composition. The first model requires a further, compensating excess mass below the (seismic) Moho in the East Barents Sea Basin region. The latter model exhibits a higher-density dome structure below the basin. Both models indicate probable old, continental lithosphere below the central part of the transect in eastern Barents Sea/Kara Sea region. Calculated temperatures of 400–1000 °C (60–200 km depth) further support this concept. Hence, the East Barents Sea Basin developed probably as an intra-continental basin within a non-extensional setting. Such basins exhibit generally crustal inhomogeneities which contributed considerably to their subsidence history. Likely structures below the East Barents Sea Basin are Pre-Permian rifts, accumulated melts derived by the Siberian mantle plume, and/or the Late Neoproterozoic Timanide Orogen.
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The crust and mantle lithosphere in the Barents Sea/Kara Sea region
Tectonophysics, 2009Co-Authors: O. Ritzmann, Jan Inge FaleideAbstract:Abstract The focus of this study is the nature of a prominent, high-velocity (S-wave) anomaly in the upper mantle below the Barents Sea–Kara Sea region and its relation to the evolution of the sedimentary basins, in particular the Permo–Triassic East Barents Sea Basin. The high-velocity anomaly exhibits a thickness of 75–100 km below the central Barents Sea and thickens considerably below the East Barents Sea Basin (150 km). The thickest part of the high-velocity anomaly follows the outline of the East Barents Sea Basin which is bended around Pai-Khoi–Novaya Zemlya Fold Belt. Density modeling of the lithosphere along a 3200 km long transect from the Barents Sea to the West Siberian Basin was used to evaluate different models for the upper mantle structure. The best fit gravity model was achieved when either assuming a 1D, horizontally- layered mantle structure, or, a forward-modeled density structure using an average Proterozoic mantle composition. The first model requires a further, compensating excess mass below the (seismic) Moho in the East Barents Sea Basin region. The latter model exhibits a higher-density dome structure below the basin. Both models indicate probable old, continental lithosphere below the central part of the transect in eastern Barents Sea/Kara Sea region. Calculated temperatures of 400–1000 °C (60–200 km depth) further support this concept. Hence, the East Barents Sea Basin developed probably as an intra-continental basin within a non-extensional setting. Such basins exhibit generally crustal inhomogeneities which contributed considerably to their subsidence history. Likely structures below the East Barents Sea Basin are Pre-Permian rifts, accumulated melts derived by the Siberian mantle plume, and/or the Late Neoproterozoic Timanide Orogen.
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Caledonian basement of the western Barents Sea
Tectonics, 2007Co-Authors: O. Ritzmann, Jan Inge FaleideAbstract:[1] Major crustal units in the western Barents Sea have been defined on the basis of depth-converted seismic reflection data, gravity and magnetic anomaly data. The seismic data revealed three types of crustal reflectivity below the sedimentary rock units, i.e., transparency, strong lower crustal reflectivity, and thoroughly reflective. The crustal structures obtained from the seismic reflection data are supported by 2D density and magnetic modeling. Three NE-SW-striking crustal units have been observed south of Bjornoya. Changes in reflectivity in southwestern Barents Sea are accompanied by gravity and/or magnetic anomalies. North of Bjornoya, two basement provinces could be distinguished. The observed outlines of the crustal blocks in the southwestern Barents Sea match with Caledonian main thrusts onshore northern Norway. We were therefore able to outline the continuation of Scandian nappe complexes in the southwestern Barents Sea. The crustal unit to the west of the Loppa High region is supposed to be a fragment of Laurentia, since the Loppa High region aligns with the Uppermost Allochthon nappes onshore, and is therefore expected to be the collision zone between Baltica and Laurentia. The southeastern crustal unit aligns with the Lower to Upper Allochthons and their Fennoscandian basement onshore. A compilation of all known thrusts and sutures in the western Barents Sea revealed the complexity of the Iapetus closure. It challenges the concept of two Caledonian main branches (NE and N). The thrusts/sutures are fan-shaped distributed across the western Barents Sea, resembling the structure of the Late Paleozoic–Mesozoic/Paleocene rift basins and basement highs in the southwestern Barents Sea.
Randi Ingvaldsen - One of the best experts on this subject based on the ideXlab platform.
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productivity in the Barents Sea response to recent climate variability
PLOS ONE, 2014Co-Authors: Padmini Dalpadado, Randi Ingvaldsen, Leif Christian Stige, Kevin R Arrigo, Solfrid Saetre Hjollo, Erik Sperfeld, Gert L Van Dijken, Are Olsen, Geir OttersenAbstract:The temporal and spatial dynamics of primary and secondary biomass/production in the Barents Sea since the late 1990s are examined using remote sensing data, observations and a coupled physical-biological model. Field observations of mesozooplankton biomass, and chlorophyll a data from transects (different Seasons) and large-scale surveys (autumn) were used for validation of the remote sensing products and modeling results. The validation showed that satellite data are well suited to study temporal and spatial dynamics of chlorophyll a in the Barents Sea and that the model is an essential tool for secondary production estimates. Temperature, open water area, chlorophyll a, and zooplankton biomass show large interannual variations in the Barents Sea. The climatic variability is strongest in the northern and eastern parts. The moderate increase in net primary production evident in this study is likely an ecosystem response to changes in climate during the same period. Increased open water area and duration of open water Season, which are related to elevated temperatures, appear to be the key drivers of the changes in annual net primary production that has occurred in the northern and eastern areas of this ecosystem. The temporal and spatial variability in zooplankton biomass appears to be controlled largely by predation pressure. In the southeastern Barents Sea, statistically significant linkages were observed between chlorophyll a and zooplankton biomass, as well as between net primary production and fish biomass, indicating bottom-up trophic interactions in this region.
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the role of the Barents Sea in the arctic climate system
Reviews of Geophysics, 2013Co-Authors: Lars Henrik Smedsrud, Randi Ingvaldsen, Tor Eldevik, Camille Li, Igor Esau, Peter M Haugan, Vidar S. LienAbstract:Present global warming is amplified in the Arctic and accompanied by unprecedented Sea ice decline. Located along the main pathway of Atlantic Water entering the Arctic, the Barents Sea is the site of coupled feedback processes that are important for creating variability in the entire Arctic air-ice-ocean system. As warm Atlantic Water flows through the Barents Sea, it loses heat to the Arctic atmosphere. Warm periods, like today, are associated with high northward heat transport, reduced Arctic Sea ice cover, and high surface air temperatures. The cooling of the Atlantic inflow creates dense water sinking to great depths in the Arctic Basins, and ~60% of the Arctic Ocean carbon uptake is removed from the carbon-saturated surface this way. Recently, anomalously large ocean heat transport has reduced Sea ice formation in the Barents Sea during winter. The missing Barents Sea winter ice makes up a large part of observed winter Arctic Sea ice loss, and in 2050, the Barents Sea is projected to be largely ice free throughout the year, with 4°C summer warming in the formerly ice-covered areas. The heating of the Barents atmosphere plays an important role both in “Arctic amplification” and the Arctic heat budget. The heating also perturbs the large-scale circulation through expansion of the Siberian High northward, with a possible link to recent continental wintertime cooling. Large air-ice-ocean variability is evident in proxy records of past climate conditions, suggesting that the Barents Sea has had an important role in Northern Hemisphere climate for, at least, the last 2500 years.
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dense water formation and circulation in the Barents Sea
Deep Sea Research Part I: Oceanographic Research Papers, 2011Co-Authors: Marius Årthun, Lars Henrik Smedsrud, Randi Ingvaldsen, Corinna SchrumAbstract:Abstract Dense water masses from Arctic shelf Seas are an important part of the Arctic thermohaline system. We present previously unpublished observations from shallow banks in the Barents Sea, which reveal large interannual variability in dense water temperature and salinity. To examine the formation and circulation of dense water, and the processes governing interannual variability, a regional coupled ice-ocean model is applied to the Barents Sea for the period 1948–2007. Volume and characteristics of dense water are investigated with respect to the initial autumn surface salinity, atmospheric cooling, and Sea-ice growth (salt flux). In the southern Barents Sea (Spitsbergen Bank and Central Bank) dense water formation is associated with advection of Atlantic Water into the Barents Sea and corresponding variations in initial salinities and heat loss at the air–Sea interface. The characteristics of the dense water on the Spitsbergen Bank and Central Bank are thus determined by the regional climate of the Barents Sea. Preconditioning is also important to dense water variability on the northern banks, and can be related to local ice melt (Great Bank) and properties of the Novaya Zemlya Coastal Current (Novaya Zemlya Bank). The dense water mainly exits the Barents Sea between Frans Josef Land and Novaya Zemlya, where it constitutes 63% (1.2 Sv) of the net outflow and has an average density of 1028.07 kg m −3 . An amount of 0.4 Sv enters the Arctic Ocean between Svalbard and Frans Josef Land. Covering 9% of the ocean area, the banks contribute with approximately 1/3 of the exported dense water. Formation on the banks is more important when the Barents Sea is in a cold state (less Atlantic Water inflow, more Sea-ice). During warm periods with high throughflow more dense water is produced broadly over the shelf by general cooling of the northward flowing Atlantic Water. However, our results indicate that during extremely warm periods (1950s and late 2000s) the total export of dense water to the Arctic Ocean becomes strongly reduced.
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heat in the Barents Sea transport storage and surface fluxes
Ocean Science, 2010Co-Authors: Lars Henrik Smedsrud, Randi Ingvaldsen, Jan Even Øie Nilsen, Øystein SkagsethAbstract:Abstract. A column model is set up for the Barents Sea to explore sensitivity of surface fluxes and heat storage from varying ocean heat transport. Mean monthly ocean transport and atmospheric forcing are synthesised and force the simulations. Results show that by using updated ocean transports of heat and freshwater the vertical mean hydrographic Seasonal cycle can be reproduced fairly well. Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production. The northern Barents Sea receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss annually in the north. The balance is achieved by a heat loss through long wave radiation all year, removing most of the summer solar heating. During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. The Barents Sea responds to such large changes by adjusting temperature and heat loss. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport leads to a spreading of warm water further north.
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Barents Sea heat - transport, storage and surface fluxes
Ocean Science Discussions, 2009Co-Authors: Lars Henrik Smedsrud, Randi Ingvaldsen, Jan Even Øie Nilsen, Øystein SkagsethAbstract:Abstract. Sensitivity of the Barents Sea to variation in ocean heat transport and surface fluxes is explored using a 1-D column model. Mean monthly ocean transport and atmospheric forcing are synthesised and force model results that reproduce the observed winter convection and surface warming and freshening well. Model results are compared to existing estimates of the ocean to air heat fluxes and horizontally averaged profiles for the southern and northern Barents Sea. Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production. The northern Barents Sea, the major part of the area, receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss in the north, the balance is achieved by long wave loss removing most of the solar heating, and the model also suggests a positive sensible heat gain. During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. Despite large changes the Barents Sea heat loss remains robust, the temperature adjusts, and the yearly cycle remains. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport probably leads to a spreading of warm water further north.
Lars Henrik Smedsrud - One of the best experts on this subject based on the ideXlab platform.
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Barents Sea ice cover reflects Atlantic inflow
2020Co-Authors: Marius Årthun, Lars Henrik Smedsrud, Tor Eldevik, Øystein SkagsethAbstract:The recent Arctic winter Sea-ice retreat is most pronounced in the Barents Sea. Using available observations of the Atlantic inflow to the Barents Sea and results from a regional ice-ocean model we assess the role of inflowing heat anomalies on Sea-ice variability. Between 1979 and 2008 the reduction of annual Sea-ice area was 15% decade −1 , and in the eastern Barents Sea the winter ice edge retreated about 240 km. The interannual variability and decrease in Sea-ice area reflects observed variability in the Atlantic inflow. The heat budget of the model is used to elucidate further how Atlantic inflow anomalies influence the Sea-ice area. It is argued that ocean heat transport into the western Barents Sea sets the boundary of the ice-free Atlantic domain and, hence, the Sea-ice extent. The regional heat content and heat loss to the atmosphere scales with the area of open ocean as a consequence. Recent Sea-ice loss is thus largely caused by an increasing ”Atlantification” of the Barents Sea. A simple prognostic model based on this scaling ‐ and the Atlantic heat source ‐ explains 58% of the variance in Sea-ice area.
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Reduced efficiency of the Barents Sea cooling machine
Nature Climate Change, 2020Co-Authors: Øystein Skagseth, Vidar S. Lien, Marius Årthun, Tor Eldevik, Helene Asbjørnsen, Lars Henrik SmedsrudAbstract:Dense water masses from the Barents Sea are an important part of the Arctic thermohaline system. Here, using hydrographic observations from 1971 to 2018, we show that the Barents Sea climate system has reached a point where ‘the Barents Sea cooling machine’—warmer Atlantic inflow, less Sea ice, more regional ocean heat loss—has changed towards less-efficient cooling. Present change is dominated by reduced ocean heat loss over the southern Barents Sea as a result of anomalous southerly winds. The outflows have accordingly become warmer. Outflow densities have nevertheless remained relatively unperturbed as increasing salinity appears to have compensated the warming inflow. However, as the upstream Atlantic Water is now observed to freshen while still relatively warm, we speculate that the Barents Sea within a few years may export water masses of record-low density to the adjacent basins and deep ocean circulation. The Barents Sea cools the ocean, and dense water masses form that flow into the global overturning circulation. Hydrographic observations from 1971 to 2018 show reduced cooling efficiency with warmer Atlantic inflow, reduced Sea ice and reduced wind-driven heat loss.
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the role of the Barents Sea in the arctic climate system
Reviews of Geophysics, 2013Co-Authors: Lars Henrik Smedsrud, Randi Ingvaldsen, Tor Eldevik, Camille Li, Igor Esau, Peter M Haugan, Vidar S. LienAbstract:Present global warming is amplified in the Arctic and accompanied by unprecedented Sea ice decline. Located along the main pathway of Atlantic Water entering the Arctic, the Barents Sea is the site of coupled feedback processes that are important for creating variability in the entire Arctic air-ice-ocean system. As warm Atlantic Water flows through the Barents Sea, it loses heat to the Arctic atmosphere. Warm periods, like today, are associated with high northward heat transport, reduced Arctic Sea ice cover, and high surface air temperatures. The cooling of the Atlantic inflow creates dense water sinking to great depths in the Arctic Basins, and ~60% of the Arctic Ocean carbon uptake is removed from the carbon-saturated surface this way. Recently, anomalously large ocean heat transport has reduced Sea ice formation in the Barents Sea during winter. The missing Barents Sea winter ice makes up a large part of observed winter Arctic Sea ice loss, and in 2050, the Barents Sea is projected to be largely ice free throughout the year, with 4°C summer warming in the formerly ice-covered areas. The heating of the Barents atmosphere plays an important role both in “Arctic amplification” and the Arctic heat budget. The heating also perturbs the large-scale circulation through expansion of the Siberian High northward, with a possible link to recent continental wintertime cooling. Large air-ice-ocean variability is evident in proxy records of past climate conditions, suggesting that the Barents Sea has had an important role in Northern Hemisphere climate for, at least, the last 2500 years.
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dense water formation and circulation in the Barents Sea
Deep Sea Research Part I: Oceanographic Research Papers, 2011Co-Authors: Marius Årthun, Lars Henrik Smedsrud, Randi Ingvaldsen, Corinna SchrumAbstract:Abstract Dense water masses from Arctic shelf Seas are an important part of the Arctic thermohaline system. We present previously unpublished observations from shallow banks in the Barents Sea, which reveal large interannual variability in dense water temperature and salinity. To examine the formation and circulation of dense water, and the processes governing interannual variability, a regional coupled ice-ocean model is applied to the Barents Sea for the period 1948–2007. Volume and characteristics of dense water are investigated with respect to the initial autumn surface salinity, atmospheric cooling, and Sea-ice growth (salt flux). In the southern Barents Sea (Spitsbergen Bank and Central Bank) dense water formation is associated with advection of Atlantic Water into the Barents Sea and corresponding variations in initial salinities and heat loss at the air–Sea interface. The characteristics of the dense water on the Spitsbergen Bank and Central Bank are thus determined by the regional climate of the Barents Sea. Preconditioning is also important to dense water variability on the northern banks, and can be related to local ice melt (Great Bank) and properties of the Novaya Zemlya Coastal Current (Novaya Zemlya Bank). The dense water mainly exits the Barents Sea between Frans Josef Land and Novaya Zemlya, where it constitutes 63% (1.2 Sv) of the net outflow and has an average density of 1028.07 kg m −3 . An amount of 0.4 Sv enters the Arctic Ocean between Svalbard and Frans Josef Land. Covering 9% of the ocean area, the banks contribute with approximately 1/3 of the exported dense water. Formation on the banks is more important when the Barents Sea is in a cold state (less Atlantic Water inflow, more Sea-ice). During warm periods with high throughflow more dense water is produced broadly over the shelf by general cooling of the northward flowing Atlantic Water. However, our results indicate that during extremely warm periods (1950s and late 2000s) the total export of dense water to the Arctic Ocean becomes strongly reduced.
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heat in the Barents Sea transport storage and surface fluxes
Ocean Science, 2010Co-Authors: Lars Henrik Smedsrud, Randi Ingvaldsen, Jan Even Øie Nilsen, Øystein SkagsethAbstract:Abstract. A column model is set up for the Barents Sea to explore sensitivity of surface fluxes and heat storage from varying ocean heat transport. Mean monthly ocean transport and atmospheric forcing are synthesised and force the simulations. Results show that by using updated ocean transports of heat and freshwater the vertical mean hydrographic Seasonal cycle can be reproduced fairly well. Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production. The northern Barents Sea receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss annually in the north. The balance is achieved by a heat loss through long wave radiation all year, removing most of the summer solar heating. During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. The Barents Sea responds to such large changes by adjusting temperature and heat loss. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport leads to a spreading of warm water further north.
Øystein Skagseth - One of the best experts on this subject based on the ideXlab platform.
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Barents Sea ice cover reflects Atlantic inflow
2020Co-Authors: Marius Årthun, Lars Henrik Smedsrud, Tor Eldevik, Øystein SkagsethAbstract:The recent Arctic winter Sea-ice retreat is most pronounced in the Barents Sea. Using available observations of the Atlantic inflow to the Barents Sea and results from a regional ice-ocean model we assess the role of inflowing heat anomalies on Sea-ice variability. Between 1979 and 2008 the reduction of annual Sea-ice area was 15% decade −1 , and in the eastern Barents Sea the winter ice edge retreated about 240 km. The interannual variability and decrease in Sea-ice area reflects observed variability in the Atlantic inflow. The heat budget of the model is used to elucidate further how Atlantic inflow anomalies influence the Sea-ice area. It is argued that ocean heat transport into the western Barents Sea sets the boundary of the ice-free Atlantic domain and, hence, the Sea-ice extent. The regional heat content and heat loss to the atmosphere scales with the area of open ocean as a consequence. Recent Sea-ice loss is thus largely caused by an increasing ”Atlantification” of the Barents Sea. A simple prognostic model based on this scaling ‐ and the Atlantic heat source ‐ explains 58% of the variance in Sea-ice area.
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Reduced efficiency of the Barents Sea cooling machine
Nature Climate Change, 2020Co-Authors: Øystein Skagseth, Vidar S. Lien, Marius Årthun, Tor Eldevik, Helene Asbjørnsen, Lars Henrik SmedsrudAbstract:Dense water masses from the Barents Sea are an important part of the Arctic thermohaline system. Here, using hydrographic observations from 1971 to 2018, we show that the Barents Sea climate system has reached a point where ‘the Barents Sea cooling machine’—warmer Atlantic inflow, less Sea ice, more regional ocean heat loss—has changed towards less-efficient cooling. Present change is dominated by reduced ocean heat loss over the southern Barents Sea as a result of anomalous southerly winds. The outflows have accordingly become warmer. Outflow densities have nevertheless remained relatively unperturbed as increasing salinity appears to have compensated the warming inflow. However, as the upstream Atlantic Water is now observed to freshen while still relatively warm, we speculate that the Barents Sea within a few years may export water masses of record-low density to the adjacent basins and deep ocean circulation. The Barents Sea cools the ocean, and dense water masses form that flow into the global overturning circulation. Hydrographic observations from 1971 to 2018 show reduced cooling efficiency with warmer Atlantic inflow, reduced Sea ice and reduced wind-driven heat loss.
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A volumetric census of the Barents Sea in a changing climate
Earth System Science Data Discussions, 2020Co-Authors: Sylvain Watelet, Vidar S. Lien, Øystein Skagseth, Helge Sagen, Oivind Ostensen, Viktor Ivshin, Jean-marie BeckersAbstract:Abstract. Due to its location between the Norwegian Sea and the Arctic Ocean, the Barents Sea is one of the main pathways of the Atlantic Meridional Overturning Circulation. Changes in its water masses potentially affect the thermohaline circulation through the alteration of the dense water formation process. In order to prospect such changes, we present here a Seasonal atlas of the Barents Sea including both temperature and salinity for the period 1965–2016. The atlas is built as a compilation of datasets from the World Ocean Database, the Polar Branch of Russian Federal ReSearch Institute of Fisheries and Oceanography, and the Norwegian Polar Institute using the Data-Interpolating Variational Analysis (DIVA) tool. DIVA allows for a minimization of the expected error with respect to the true field. The atlas is used to provide a volumetric analysis of water mass characteristics and an estimation of the ocean heat and freshwater contents. The results show a recent Atlantification of the Barents Sea, i.e. a general increase of both temperature and salinity, while its density remains stable. The atlas is made freely accessible as user-friendly NetCDF files to encourage further reSearch in the Barents Sea physics ( https://doi.org/10.21335/NMDC-2058021735 , Watelet et al. (2020)).
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heat in the Barents Sea transport storage and surface fluxes
Ocean Science, 2010Co-Authors: Lars Henrik Smedsrud, Randi Ingvaldsen, Jan Even Øie Nilsen, Øystein SkagsethAbstract:Abstract. A column model is set up for the Barents Sea to explore sensitivity of surface fluxes and heat storage from varying ocean heat transport. Mean monthly ocean transport and atmospheric forcing are synthesised and force the simulations. Results show that by using updated ocean transports of heat and freshwater the vertical mean hydrographic Seasonal cycle can be reproduced fairly well. Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production. The northern Barents Sea receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss annually in the north. The balance is achieved by a heat loss through long wave radiation all year, removing most of the summer solar heating. During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. The Barents Sea responds to such large changes by adjusting temperature and heat loss. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport leads to a spreading of warm water further north.
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Barents Sea heat - transport, storage and surface fluxes
Ocean Science Discussions, 2009Co-Authors: Lars Henrik Smedsrud, Randi Ingvaldsen, Jan Even Øie Nilsen, Øystein SkagsethAbstract:Abstract. Sensitivity of the Barents Sea to variation in ocean heat transport and surface fluxes is explored using a 1-D column model. Mean monthly ocean transport and atmospheric forcing are synthesised and force model results that reproduce the observed winter convection and surface warming and freshening well. Model results are compared to existing estimates of the ocean to air heat fluxes and horizontally averaged profiles for the southern and northern Barents Sea. Our results indicate that the ~70 TW of heat transported to the Barents Sea by ocean currents is lost in the southern Barents Sea as latent, sensible, and long wave radiation, each contributing 23–39 TW to the total heat loss. Solar radiation adds 26 TW in the south, as there is no significant ice production. The northern Barents Sea, the major part of the area, receives little ocean heat transport. This leads to a mixed layer at the freezing point during winter and significant ice production. There is little net surface heat loss in the north, the balance is achieved by long wave loss removing most of the solar heating, and the model also suggests a positive sensible heat gain. During the last decade the Barents Sea has experienced an atmospheric warming and an increased ocean heat transport. Despite large changes the Barents Sea heat loss remains robust, the temperature adjusts, and the yearly cycle remains. Decreasing the ocean heat transport below 50 TW starts a transition towards Arctic conditions. The heat loss in the Barents Sea depend on the effective area for cooling, and an increased heat transport probably leads to a spreading of warm water further north.
Corinna Schrum - One of the best experts on this subject based on the ideXlab platform.
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Ocean surface heat flux variability in the Barents Sea
Journal of Marine Systems, 2020Co-Authors: M. Årthun, Corinna SchrumAbstract:Water mass transformation processes in the Barents Sea and their interannual to decadal variability are studied using a regional coupled ice-ocean model and observational data. Long-term data allows for assessment of temporal and spatial variability in water mass properties and distribution, and the influence on air-Sea exchange of heat and CO2. The Barents Sea ocean climate shows substantial interannual to decadal variability between 1948 and 2007. Variations in ocean heat transport associated with the Atlantic inflow modulate both the Barents Sea mean temperature (heat content) and the Sea-ice extent. An increasing ocean heat transport is largely responsible for the Sea-ice retreat in the Barents Sea during recent decades. The increased open ocean area causes a larger heat loss to the atmosphere, which provides sufficient cooling to transform a majority of the warm Atlantic inflow into cold, dense water before it is exported into the deep Arctic Ocean. The Barents Sea is thus an effective ocean cooler, and the dense outflow into the Arctic Ocean displays large variability, corresponding to variations in the Atlantic inflow. Variability of water mass transformation processes related to changes in surface heat loss, Sea-ice growth and corresponding salt fluxes, and the surface salinity before winter, also leads to substantial variations in the thermohaline properties of dense water. In the southern Barents Sea this is associated with the Atlantic inflow and thus the regional climate, whereas variable preconditioning of surface waters by ice melt and fresh coastal waters are more important in the northern Barents Sea. Oceanic heat loss and convective processes also favor an uptake of atmospheric CO2. Calculated air-Sea CO2 fluxes for the period 2000-2007 identifies the southern Barents Sea as a particularly efficient sink of atmospheric CO2. Temporal and spatial variability of water mass properties and Sea-ice extent are important to the CO2 uptake, although wind speed is the major driver of variability
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dense water formation and circulation in the Barents Sea
Deep Sea Research Part I: Oceanographic Research Papers, 2011Co-Authors: Marius Årthun, Lars Henrik Smedsrud, Randi Ingvaldsen, Corinna SchrumAbstract:Abstract Dense water masses from Arctic shelf Seas are an important part of the Arctic thermohaline system. We present previously unpublished observations from shallow banks in the Barents Sea, which reveal large interannual variability in dense water temperature and salinity. To examine the formation and circulation of dense water, and the processes governing interannual variability, a regional coupled ice-ocean model is applied to the Barents Sea for the period 1948–2007. Volume and characteristics of dense water are investigated with respect to the initial autumn surface salinity, atmospheric cooling, and Sea-ice growth (salt flux). In the southern Barents Sea (Spitsbergen Bank and Central Bank) dense water formation is associated with advection of Atlantic Water into the Barents Sea and corresponding variations in initial salinities and heat loss at the air–Sea interface. The characteristics of the dense water on the Spitsbergen Bank and Central Bank are thus determined by the regional climate of the Barents Sea. Preconditioning is also important to dense water variability on the northern banks, and can be related to local ice melt (Great Bank) and properties of the Novaya Zemlya Coastal Current (Novaya Zemlya Bank). The dense water mainly exits the Barents Sea between Frans Josef Land and Novaya Zemlya, where it constitutes 63% (1.2 Sv) of the net outflow and has an average density of 1028.07 kg m −3 . An amount of 0.4 Sv enters the Arctic Ocean between Svalbard and Frans Josef Land. Covering 9% of the ocean area, the banks contribute with approximately 1/3 of the exported dense water. Formation on the banks is more important when the Barents Sea is in a cold state (less Atlantic Water inflow, more Sea-ice). During warm periods with high throughflow more dense water is produced broadly over the shelf by general cooling of the northward flowing Atlantic Water. However, our results indicate that during extremely warm periods (1950s and late 2000s) the total export of dense water to the Arctic Ocean becomes strongly reduced.
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Ocean surface heat flux variability in the Barents Sea
Journal of Marine Systems, 2010Co-Authors: Marius Årthun, Corinna SchrumAbstract:Abstract A 40 year (1958–1997) hindcast simulation from the regional coupled ice–ocean model HAMSOM is used to study climate relevant processes in the Barents Sea and their interannual to decadal variability. Compared to observations the model captures the variability in temperature and ice extent in a satisfying manner. The heat input through the Barents Sea Opening (BSO) is effectively lost through intense atmosphere–ocean heat exchange within the Barents Sea. Correlation analysis suggests that heat transport through the BSO leads the Barents Sea heat content by 1–10 months, while the heat content leads the air–Sea heat fluxes with 1–5 months. Averaged over the period the advected heat input is 32 TW, augmented by 79 TW of shortwave radiation and reduced by 113 TW through longwave radiation and latent and sensible heat loss. Including the sensible heat loss at the ice–ocean boundary yields an oceanic heat loss in the Barents Sea of 40 TW. Cooling of Atlantic Water is very efficient just east of the BSO, and contributes to 50% of the total heat loss. Significant positive trends in both heat transport through the BSO and solar radiation, combined with a reduction in Seasonal ice cover cause increased oceanic heat loss. Excess heat still enters the Barents Sea and a significant warming is observed in the northern areas. Sea-ice acts as an effective insulator against oceanic heat loss resulting in 4 TW of net heat input at the Sea-ice surface. This heat flux balances the ice–ocean heat budget and the corresponding ice melt compensates for net ice production at the ice–ocean interface and ice advection into the Barents Sea.
