Heat content in the Norwegian Sea, 1995–2010

Abstract Skagseth, Ø., and Mork, K. A. 2012. Heat content in the Norwegian Sea, 1995–2010. – ICES Journal of Marine Science, 69: 826–832. Spatio-temporal hydrographic data from the Nordic Seas during spring over the period 1995–2010 were investigated in terms of the relative heat content (RHC) above the density surface σt = 27.9, chosen to capture the changes in Atlantic water (AW). Focusing on the Atlantic (eastern) domain of the Nordic Seas, negative anomalies dominated the early part of the series. There was then a gradual transition towards an absolute maximum in 2003/2004, followed by a small reduction with positive values for the period ending in 2010. The maps clearly reveal the events of propagating signals. The variability is regionally comparable, but the persistence on a year-to-year basis is higher in the Lofoten Basin than in the Norwegian Basin. Compared with other studies, in this study, the estimated trend in the RHC of the Nordic Seas was larger than for the global mean and the North Atlantic. The warming of the Nordic Seas derives mainly from the advection of warmer inflowing AW and less from changes in local air–sea heat fluxes. The importance of advection suggests that the variability of the Norwegian Sea's ocean climate can, to a large extent, be predicted based on the observed hydrographic conditions.

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Variations of oceanic and atmospheric heat fluxes in the North Atlantic and their link to the North Atlantic Oscillation Index

10.5194/egusphere-egu2020-594 ◽

2020 ◽

Author(s):

Diana Iakovleva ◽

Igor Bashmachnikov

Keyword(s):

North Atlantic ◽

Heat Content ◽

Heat Fluxes ◽

Upper Ocean ◽

Subpolar Gyre ◽

Heat Advection ◽

Norwegian Sea ◽

The North ◽

The North Atlantic ◽

The North Atlantic Oscillation

Interannual variations in the upper ocean heat and freshwater contents in the subpolar North Atlantic has important climatic effect. It affects the intensity of deep convection, which, in turn, forms the link between upper and deep ocean circulation of the global ocean Conveyor Belt.The upper ocean heat content is primarily affected by two main process: by the ocean-atmosphere heat exchange and by oceanic heat advection. The intensity of both fluxes in the subpolar gyre is linked to the character of atmospheric circulation, largely determined by the phase of the North Atlantic Oscillation (NAO).To study the interannual variability of the oceanic heat advection (in the upper 500th meters layer) we compare the results from four different data-sets: ARMOR-3D (1993-2018), SODA3.4.2 and SODA3.12.2 (1980-2017), and ORAS5 (1958-2017). The ocean-atmosphere heat exchange is accessed as the sum of the latent and the sensible heat fluxes, obtained from OAFlux data-set (1958-2016).The oceanic heat advection to the Labrador and to the Irminger seas has high negative correlation (-0.79) with that into the Nordic Seas. During the years with high winter NAO Index (NAOI) the oceanic heat advection into the Subpolar Gyre decreases, while to the Nordic Seas &#8211; increases. These variations go in parallel with the intensification of the Norwegian, the West Spitsbergen and the slope East Greenland currents and weakening of the West Greenland and the Irminger Currents. During the years with high NAOI, the ocean heat release (both sensible and latent) over the Labrador and Irminger seas increases, but over the Norwegian Sea it decreases.In summary, the results show that, during the positive NAO phase, the observed decrease of the heat content in the upper Labrador and Irminger seas is linked to both, a higher oceanic het release and a lower intensity of advection of warm water from the south. In the Norwegian Sea, the opposite sign of variations of the fluxes above leads to a simultaneous warming of the upper ocean.The investigation is supported by the Russian Scientific Foundation (RSF), number of project 17-17-01151.&#160;&#160;

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Recent Warming and Freshening of the Norwegian Sea Observed by Argo Data

Journal of Climate ◽

10.1175/jcli-d-18-0591.1 ◽

2019 ◽

Vol 32 (12) ◽

pp. 3695-3705 ◽

Cited By ~ 13

Author(s):

Kjell Arne Mork ◽

Øystein Skagseth ◽

Henrik Søiland

Keyword(s):

Time Scales ◽

Heat Content ◽

Atlantic Water ◽

Heat Fluxes ◽

Ocean Heat Content ◽

Ekman Transport ◽

Arctic Water ◽

Argo Data ◽

Norwegian Sea ◽

Using Data

Abstract Climate variability in the Norwegian Sea, comprising the Norwegian and Lofoten Basins, was investigated based upon monthly estimates of ocean heat and freshwater contents using data from Argo floats during 2002–18. Both local air–sea exchange and advective processes were examined and quantified for monthly to interannual time scales. In the recent years, 2011–18, the Norwegian Sea experienced a decoupling of the temperature and salinity, with a simultaneous warming and freshening trend. This was mainly explained by two different processes; reduced ocean heat loss to the atmosphere and advection of fresher Atlantic water into the Norwegian Sea. The local air–sea heat fluxes are important in modifying the ocean heat content, although this relationship varied with time scale and basins. On time scales exceeding 4 months in the Lofoten Basin and 6 months in the Norwegian Basin, the air–sea heat flux explained half or even more of the local ocean heat content change. There were both a short-term and long-term response of the wind forcing on the ocean heat content. The monthly to seasonal response of increased southerly wind cooled and freshened the Norwegian Basin, due to eastward surface Ekman transport, and increased the influence of Arctic Water. However, after about a 1-yr delay the ocean warmed and became saltier due to an increased advection of Atlantic Water into the region. Increased westerly winds decreased the ocean heat content in both cases due to increased transport of Arctic Water into the Norwegian Sea.

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Changes in Atlantic water properties: an important factor in the European Arctic marine climate

ICES Journal of Marine Science ◽

10.1093/icesjms/fss068 ◽

2012 ◽

Vol 69 (5) ◽

pp. 864-869 ◽

Cited By ~ 78

Author(s):

Waldemar Walczowski ◽

Jan Piechura ◽

Ilona Goszczko ◽

Piotr Wieczorek

Keyword(s):

Time Series ◽

Environmental Changes ◽

Heat Content ◽

Atlantic Water ◽

Primary Role ◽

Nordic Seas ◽

Water Properties ◽

The North ◽

European Arctic ◽

Marine Climate

Abstract Walczowski, W., Piechura, J., Goszczko, I., and Wieczorek, P. 2012. Changes in Atlantic water properties: an important factor in the European Arctic marine climate. – ICES Journal of Marine Science, 69: 864–869. The advection of warm Atlantic water (AW) through the Nordic Seas and its transformation (cooling and freshening) is one of the most important climatological processes in the region. Time-series of hydrographic observations in the northern Nordic Seas and the Fram Strait region are presented and analysed. Significant variability in the properties of AW has been observed in recent years. A 15-year time-series of summer observations indicate positive trends in salinity and temperature and two 5–6-year cycles. The northward advance of AW in 2006 was an unprecedented event. The position of the warm-water tongue shifted more than 350 km to the north, and temperatures in the West Spitsbergen Current reached the highest values ever recorded. These changes in AW temperature, heat content, and northward transport had a strong influence on the oceanic climate and sea-ice conditions north of Svalbard. These oceanic signals led to environmental changes that confirm the primary role of the ocean in shaping the climate of the region.

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Polymastiidae (Porifera: Demospongiae) of the Nordic and Siberian Seas

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315417000285 ◽

2017 ◽

Vol 98 (6) ◽

pp. 1273-1335 ◽

Cited By ~ 9

Author(s):

Alexander Plotkin ◽

Elena Gerasimova ◽

Hans Tore Rapp

Keyword(s):

North Atlantic ◽

Related Species ◽

Molecular Data ◽

Wide Distribution ◽

Morphological Data ◽

Nordic Seas ◽

Norwegian Sea ◽

The North ◽

Western Norway ◽

The North Atlantic

Polymastiidae (Porifera: Demospongiae) of the Nordic and Siberian Seas are revised and compared with the related species of the North Atlantic based on the morphological data from the type and comparative material and the molecular data from fresh samples. Twenty species from six polymastiid genera are recorded. Two species,Polymastia svensenifrom Western Norway andSpinularia njordifrom the Norwegian Sea, are new to science. One species,Polymastia andrica, is new to the Nordic Seas and two species,Polymastiacf.bartlettiandP. penicillus, are new to the Scandinavian Coast. Distribution of the polymastiids in the North Atlantic and Arctic is discussed and the allegedly wide distribution ofSpinularia sarsiiandS. spinulariais questioned.

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Atlantic water in the Faroe area: sources and variability

ICES Journal of Marine Science ◽

10.1093/icesjms/fss028 ◽

2012 ◽

Vol 69 (5) ◽

pp. 802-808 ◽

Cited By ~ 28

Author(s):

Karin Margretha H. Larsen ◽

Hjálmar Hátún ◽

Bogi Hansen ◽

Regin Kristiansen

Keyword(s):

North Atlantic ◽

Large Scale ◽

Atlantic Water ◽

Heat Fluxes ◽

The North ◽

Salinity Variability ◽

Increasing Trend ◽

The North Atlantic ◽

Pass Through ◽

Northeastern Atlantic

Abstract Larsen, K. M. H., Hátún, H., Hansen, B., and Kristiansen, R. 2012. Atlantic water in the Faroe area: sources and variability. – ICES Journal of Marine Science, 69: 802–808. The inflow of Atlantic water (AW) across the Greenland–Scotland Ridge and into the Nordic Seas controls both physical and biological conditions in the northeastern Atlantic through its transport of heat, salt, and other properties. The two main branches of this flow pass through the Iceland–Faroe Gap and the Faroe–Shetland Channel, respectively. Regular monitoring along four standard sections crossing these flows provides time-series of the AW temperature and salinity variability since the late 1980s. The analysis of these series presented shows a persistent increasing trend in both temperature and salinity, modulated by smaller subdecadal oscillations. Using supplementary data sources, the previously established link between the large-scale circulation in the North Atlantic and Atlantic inflow properties is supported. Salinity is also impacted by large changes in the Bay of Biscay source waters, and upstream air–sea heat fluxes modulate temperature. Relationships between changes in transport and associated residence time, and the modifying strength of the air–sea interaction and mixing, are also discussed.

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Recent water mass changes reveal mechanisms of ocean warming

Journal of Climate ◽

10.1175/jcli-d-20-0355.1 ◽

2020 ◽

pp. 1-52

Author(s):

Jan D. Zika ◽

Jonathan M. Gregory ◽

Elaine L. McDonagh ◽

Alice Marzocchi ◽

Louis Clément

Keyword(s):

Water Mass ◽

Spatial Coherence ◽

Geographical Location ◽

Heat Content ◽

Transformation Method ◽

Atlantic Water ◽

Meridional Overturning Circulation ◽

Ocean Heat Content ◽

The North ◽

Content Change

AbstractOver 90% of the build up of additional heat in the earth system over recent decades is contained in the ocean. Since 2006 new observational programs have revealed heterogeneous patterns of ocean heat content change. It is unclear how much of this heterogeneity is due to heat being added to and mixed within the ocean leading to material changes in water mass properties or due to changes in circulation which redistribute existing water masses. Here we present a novel diagnosis of the ‘material’ and ‘redistributed’ contributions to regional heat content change between 2006 and 2017 based on a new Minimum Transformation Method informed by both water mass transformation and optimal transportation theory. We show that material warming has large spatial coherence. The material change tends to be smaller than the redistributed change at any geographical location, however it sums globally to the net warming of the ocean, while the redistributed component sums, by design, to zero. Material warming is robust over the time period of this analysis, whereas the redistributed signal only emerges from the variability in a few regions. In the North Atlantic, water mass changes indicate substantial material warming while redistribution cools the subpolar region due to a slowdown in the Meridional Overturning Circulation. Warming in the Southern Ocean is explained by material warming and by anomalous southward heat transport of 118 ± 50 TWdue to redistribution. Our results suggest near termprojections of ocean heat content change and therefore sea level change will hinge on understanding and predicting changes in ocean redistribution.

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The coherence of the oceanic heat transport through the Nordic seas: oceanic heat budget and interannual variability

10.5194/os-2020-109 ◽

2020 ◽

Author(s):

Anna V. Vesman ◽

Igor L. Bashmachnikov ◽

Pavel A. Golubkin ◽

Roshin P. Raj

Keyword(s):

Heat Budget ◽

Atlantic Water ◽

Heat Fluxes ◽

The Arctic ◽

Ekman Pumping ◽

Sea Ice Extent ◽

Weather Types ◽

Study Region ◽

Nordic Seas ◽

Local Climate

Abstract. Atlantic Water is the main source of the heat and salt in the Arctic. On the way to the Arctic Ocean via the Nordic Seas, it interacts and mixes with other water masses which affects sea ice extent and deep water formation. The Atlantic Water heat transported into the Nordic Seas has a significant impact on the local climate and is investigated here along with its inter-annual variability using the ARMOR3D dataset, which is a collection of 3D monthly temperature, salinity and geostrophic velocities fields, derived from in situ and satellite data on a regular grid since 1993. The study region includes the eastern part of the Nordic seas, i.e., seven latitudinal transects from Svinoy section (65° N) to the northern part of the Fram Strait (78.8° N). The Atlantic Water heat advection decreases northwards, as a significant amount of heat is lost to the atmosphere and due to mixing with surrounding waters. As observed, the imbalance of heat fluxes in the upper layer leads to an increase in the upper ocean mean temperature over most of the study region. The correlations of the interannual variations of the advective heat fluxes rapidly drop from Svinoy to Jan Mayen sections and between Bear Island and Sorkapp sections. This is a result of a differential damping of periodicities (the 2–3 year and 5–6 year oscillations), as well as of different signs of the tendencies over the latest decades. The heat fluxes at all sections show a consistent change with meridional (C) and western (W) weather types, which is due to the different direction of the Ekman pumping associated with each of the weather types. A certain link to the NAO, AO and EA atmospheric indices is observed only at the southern sections.

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Propagation of Thermohaline Anomalies and their predictive potential along the Atlantic water pathway

Journal of Climate ◽

10.1175/jcli-d-20-1007.1 ◽

2021 ◽

pp. 1-60

Keyword(s):

North Atlantic ◽

Physical Mechanism ◽

Atlantic Water ◽

The Arctic ◽

North Atlantic Current ◽

The North ◽

Spatio Temporal ◽

Prediction Systems ◽

Water Pathway ◽

Atlantic Current

Abstract We assess to what extent seven state-of-the-art dynamical prediction systems can retrospectively predict winter sea surface temperature (SST) in the subpolar North Atlantic and the Nordic Seas in the period 1970-2005. We focus on the region where warm water flows poleward, i.e., the Atlantic water pathway to the Arctic, and on interannual-to-decadal time scales. Observational studies demonstrate predictability several years in advance in this region, but we find that SST skill is low with significant skill only at lead time 1-2 years. To better understand why the prediction systems have predictive skill or lack thereof, we assess the skill of the systems to reproduce a spatio-temporal SST pattern based on observations. The physical mechanism underlying this pattern is a propagation of oceanic anomalies from low to high latitudes along the major currents; the North Atlantic Current and the Norwegian Atlantic Current. We find that the prediction systems have difficulties in reproducing this pattern. To identify whether the misrepresentation is due to incorrect model physics, we assess the respective uninitialized historical simulations. These simulations also tend to misrepresent the spatio-temporal SST pattern, indicating that the physical mechanism is not properly simulated. However, the representation of the pattern is slightly degraded in the predictions compared to historical runs, which could be a result of initialization shocks and forecast drift effects. Ways to enhance predictions, could be through improved initialization, and better simulation of poleward circulation of anomalies. This might require model resolutions in which flow over complex bathymetry and physics of mesoscale ocean eddies and their interactions with the atmosphere are resolved.

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Stability and forcing of the Iceland-Faroe inflow of water, heat, and salt to the Arctic

Ocean Science Discussions ◽

10.5194/osd-7-1245-2010 ◽

2010 ◽

Vol 7 (4) ◽

pp. 1245-1287 ◽

Cited By ~ 1

Author(s):

B. Hansen ◽

H. Hátún ◽

R. Kristiansen ◽

S. M. Olsen ◽

S. Østerhus

Keyword(s):

Sea Level ◽

Thermohaline Circulation ◽

Arctic Region ◽

Atlantic Water ◽

Volume Transport ◽

The Arctic ◽

Nordic Seas ◽

The North ◽

Significant Seasonal Variation ◽

System Coupling

Abstract. The flow of Atlantic water across the Greenland-Scotland Ridge (Atlantic inflow) is critical for conditions in the Nordic Seas and Arctic Ocean by importing heat and salt. Here, we present a decade-long series of measurements from the Iceland-Faroe inflow branch (IF-inflow), which carries almost half the total Atlantic inflow. The observations show no significant trend in volume transport of Atlantic water, but temperature and salinity increased during the observational period. On shorter time scales, the observations show considerable variations but no statistically significant seasonal variation is observed and even weekly averaged transport values were consistently uni-directional from the Atlantic into the Nordic Seas. Combining transport time-series with sea level height from satellite altimetry and wind stress reveals that the force driving the IF-inflow across the topographic barrier of the Ridge is mainly generated by a pressure gradient that is due to a continuously maintained low sea level in the Southern Nordic Seas. This links the IF-inflow to the estuarine and thermohaline processes that generate outflow from the Nordic Seas and lower its sea level. The IF-inflow is an important component of the system coupling the Arctic region to the North Atlantic through the thermohaline circulation, which has been predicted to weaken in the 21st century. Our observations show no indication of weakening, as yet.

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Approaching the Arctic: the occurrence of Parin’s spinyfin Diretmichthys parini (Beryciformes: Diretmidae) in the Nordic Seas

Fauna norvegica ◽

10.5324/fn.v40i0.3351 ◽

2020 ◽

Vol 40 ◽

pp. 43-46

Author(s):

Arve Lynghammar ◽

Ingvar Byrkjedal ◽

Berit Margrete Bugjerde ◽

Rupert Wienerroither

Keyword(s):

North Sea ◽

Fish Species ◽

The Arctic ◽

Nordic Seas ◽

Norwegian Sea ◽

The North ◽

Distributional Change ◽

Subtropical Fish ◽

The North Sea ◽

Icelandic Waters

Two adult specimens of the tropical to subtropical fish species Diretmichthys parini are reported from the North Sea and the northern Norwegian Sea, respectively. Both were accidentally caught as bycatch by commercial trawlers. Although not uncommon in Icelandic waters, it has not been documented from the Nordic Seas previously. In light of the major currents and water temperatures in the area, this is puzzling. Whether this pattern reflects a true distributional change or increased awareness and reporting from fishermen is not known.

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