Simulated Variability of the Arctic Ocean Freshwater Balance 1948–2001

Abstract The Arctic Ocean freshwater balance over the period 1948–2001 is examined using results from a hindcast simulation with an ocean–sea ice model of the Atlantic and Arctic Oceans. Atmospheric forcing is taken from the NCEP–NCAR reanalysis and different terrestrial freshwater sources as well as the Bering Strait throughflow are specified as constant seasonal cycles. The long-term variability of the Arctic Ocean liquid freshwater content is determined by the variability of lateral exchanges with the subpolar seas. Surface freshwater flux variability is dominated by the thermodynamic growth of sea ice. This component of the freshwater balance has larger variability at interannual frequencies. The Arctic Ocean liquid freshwater content was at a maximum in the middle of the 1960s. Extremely low liquid freshwater export through Fram Strait caused this maximum in the freshwater content. The low export rate was related to weak volume transports in the East Greenland Current. Low volume transports were forced by a reduction in sea surface height across Fram Strait, triggered by anomalous meltwater from Barents Sea ice export that was carried toward Fram Strait with the West Spitzbergen Current. After the 1960s maximum liquid freshwater content, the Arctic Ocean gradually returned to an equilibrium between export through the passages toward the Atlantic and the freshwater sources.

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Freshwater pulses in the eastern Arctic Ocean during Saalian and Early Weichselian ice-sheet collapse

Quaternary Research ◽

10.1016/j.yqres.2003.07.008 ◽

2003 ◽

Vol 60 (3) ◽

pp. 243-251 ◽

Cited By ~ 26

Author(s):

Jochen Knies ◽

Christoph Vogt

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Large Scale ◽

Barents Sea ◽

The Arctic ◽

Fram Strait ◽

Nordic Seas ◽

The Arctic Ocean ◽

Transpolar Drift ◽

Mis 5

AbstractImproved multiparameter records from the northern Barents Sea margin show two prominent freshwater pulses into the Arctic Ocean during MIS 5 that significantly disturbed the regional oceanic regime and probably affected global climate. Both pulses are associated with major iceberg-rafted debris (IRD) events, revealing intensive iceberg/sea ice melting. The older meltwater pulse occurred near the MIS 5/6 boundary (∼131,000 yr ago); its ∼2000 year duration and high IRD input accompanied by high illite content suggest a collapse of large-scale Saalian Glaciation in the Arctic Ocean. Movement of this meltwater with the Transpolar Drift current into the Fram Strait probably promoted freshening of Nordic Seas surface water, which may have increased sea-ice formation and significantly reduced deep-water formation. A second pulse of freshwater occurred within MIS 5a (∼77,000 yr ago); its high smectite content and relatively short duration is possibly consistent with sudden discharge of Early Weichselian ice-dammed lakes in northern Siberia as suggested by terrestrial glacial geologic data. The influence of this MIS 5a meltwater pulse has been observed at a number of sites along the Transpolar Drift, through Fram Strait, and into the Nordic Seas; it may well have been a trigger for the North Atlantic cooling event C20.

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Unprecedented decline of sea ice thickness in Fram Strait in 2017-2018

10.5194/egusphere-egu21-6427 ◽

2021 ◽

Author(s):

Hiroshi Sumata ◽

Laura de Steur ◽

Dmitry Divine ◽

Olga Pavlova ◽

Sebastian Gerland

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Barents Sea ◽

North Atlantic Ocean ◽

The Arctic ◽

Ice Thickness ◽

Fram Strait ◽

Sea Ice Thickness ◽

Drift Speed ◽

The Arctic Ocean

Fram Strait is the major gateway connecting the Arctic Ocean and the northern North Atlantic Ocean where about 80 to 90% of sea ice outflow from the Arctic Ocean takes place. Long-term observations from the Fram Strait Arctic Outflow Observatory maintained by the Norwegian Polar Institute captured an unprecedented decline of sea ice thickness in 2017 &#8211; 2018 since comprehensive observations started in the early 1990s. Four Ice Profiling Sonars moored in the East Greenland Current in Fram Strait simultaneously recorded 50 &#8211; 70 cm decline of annual mean ice thickness in comparison with preceding years. A backward trajectory analysis revealed that the decline was attributed to an anomalous sea level pressure pattern from 2017 autumn to 2018 summer. Southerly wind associated with a dipole pressure anomaly between Greenland and the Barents Sea prevented southward motion of ice floes north of Fram Strait. Hence ice pack was exposed to warm Atlantic Water in the north of Fram Strait 2 &#8211; 3 times longer than the average year, allowing more melt to happen. At the same time, the dipole anomaly was responsible for the slowest observed annual mean ice drift speed in Fram Strait in the last two decades. As a consequence of the record minimum of ice thickness and the slowest drift speed, the sea ice volume transport through the Fram Strait dropped by more than 50% in comparison with the 2010 &#8211; 2017 average.

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Arctic Ocean circulation and variability – advection and external forcing encounter constraints and local processes

Ocean Science Discussions ◽

10.5194/osd-8-2313-2011 ◽

2011 ◽

Vol 8 (6) ◽

pp. 2313-2376 ◽

Cited By ~ 2

Author(s):

B. Rudels

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Ocean Circulation ◽

Barents Sea ◽

Atlantic Water ◽

The Arctic ◽

Fram Strait ◽

Intermediate Layers ◽

The Arctic Ocean ◽

Almost All

Abstract. The first hydrographic data from the Arctic Ocean, the section from the Laptev Sea to the passage between Greenland and Svalbard obtained by Nansen on the drift by Fram 1893–1896, aptly illustrate the main features of Arctic Ocean oceanography and indicate possible processes active in transforming the water masses in the Arctic Ocean. Many, perhaps most, of these processes were identified already by Nansen, who put his mark on almost all subsequent research in the Arctic Ocean. Here we shall revisit some key questions and follow how our understanding has evolved from the early 20th century to present. What questions, if any, can now be regarded as solved and which remain still open? Five different but connected topics will be discussed: (1) The low salinity surface layer and the storage and export of freshwater. (2) The vertical heat transfer from the Atlantic water to sea ice and to the atmosphere. (3) The circulation and mixing of the two Atlantic inflow branches. (4) The formation and circulation of deep and bottom waters in the Arctic Ocean. (5) The exchanges through Fram Strait. Foci will be on the potential effects of increased freshwater input and reduced sea ice export on the freshwater storage and residence time in the Arctic Ocean, on the deep waters of the Makarov Basin and on the circulation and relative importance of the two inflows, over the Barents Sea and through Fram Strait, for the distribution of heat in the intermediate layers of the Arctic Ocean.

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Arctic Ocean circulation and variability – advection and external forcing encounter constraints and local processes

Ocean Science ◽

10.5194/os-8-261-2012 ◽

2012 ◽

Vol 8 (2) ◽

pp. 261-286 ◽

Cited By ~ 70

Author(s):

B. Rudels

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Ocean Circulation ◽

Barents Sea ◽

Atlantic Water ◽

The Arctic ◽

Fram Strait ◽

Intermediate Layers ◽

The Arctic Ocean ◽

Almost All

Abstract. The first hydrographic data from the Arctic Ocean, the section from the Laptev Sea to the passage between Greenland and Svalbard obtained by Nansen on his drift with Fram 1893–1896, aptly illustrate the main features of Arctic Ocean oceanography and indicate possible processes active in transforming the water masses in the Arctic Ocean. Many, perhaps most, processes were identified already by Nansen, who put his mark on almost all subsequent research in the Arctic. Here we shall revisit some key questions and follow how our understanding has evolved from the early 20th century to present. What questions, if any, can now be regarded as solved and which remain still open? Five different but connected topics will be discussed: (1) The low salinity surface layer and the storage and export of freshwater. (2) The vertical heat transfer from the Atlantic water to sea ice and to the atmosphere. (3) The circulation and mixing of the two Atlantic inflow branches. (4) The formation and circulation of deep and bottom waters in the Arctic Ocean. (5) The exchanges through Fram Strait. Foci will be on the potential effects of increased freshwater input and reduced sea ice export on the freshwater storage and residence time in the Arctic Ocean, on the deep waters of the Makarov Basin, and on the circulation and relative importance of the two inflows, over the Barents Sea and through Fram Strait, for the distribution of heat in the intermediate layers of the Arctic Ocean.

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

Geophysical Research Letters ◽

10.1029/2019gl086682 ◽

2020 ◽

Vol 47 (3) ◽

Cited By ~ 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

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

10.5194/egusphere-egu2020-8422 ◽

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

The Arctic Ocean has been receiving&#160;more of the warm and saline Atlantic Water in the past&#160;decades. This water mass enters the Arctic Ocean via two Arctic gateways: the Barents Sea Opening and the Fram Strait.&#160;Here, we focus on the fractionation of Atlantic Water at these two gateways using a Lagrangian approach based on satellite-derived geostrophic velocities.&#160;Simulated particles are released at 70N at the inner and outer branch of the North Atlantic current system&#160;in the Nordic Seas. The trajectories toward the Fram Strait and Barents Sea Opening&#160;are found to be&#160;largely steered by the bottom topography and there is an indication of an&#160;anti-phase relationship in the number of particles reaching the gateways. There is, however, a significant&#160;cross-over of particles from the outer branch to the inner branch and into the Barents Sea, which is&#160;found to be related to high eddy kinetic energy between the branches. This cross-over may be important for Arctic climate variability.

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Effects of sea ice cover on satellite-detected primary production in the Arctic Ocean

Biology Letters ◽

10.1098/rsbl.2016.0223 ◽

2016 ◽

Vol 12 (11) ◽

pp. 20160223 ◽

Cited By ~ 35

Author(s):

Mati Kahru ◽

Zhongping Lee ◽

B. Greg Mitchell ◽

Cynthia D. Nevison

Keyword(s):

Sea Ice ◽

Primary Production ◽

Arctic Ocean ◽

Barents Sea ◽

Net Primary Production ◽

Arctic Sea Ice ◽

The Arctic ◽

Primary Input ◽

High Productivity ◽

The Arctic Ocean

The influence of decreasing Arctic sea ice on net primary production (NPP) in the Arctic Ocean has been considered in multiple publications but is not well constrained owing to the potentially large errors in satellite algorithms. In particular, the Arctic Ocean is rich in coloured dissolved organic matter (CDOM) that interferes in the detection of chlorophyll a concentration of the standard algorithm, which is the primary input to NPP models. We used the quasi-analytic algorithm (Lee et al . 2002 Appl. Opti. 41 , 5755−5772. ( doi:10.1364/AO.41.005755 )) that separates absorption by phytoplankton from absorption by CDOM and detrital matter. We merged satellite data from multiple satellite sensors and created a 19 year time series (1997–2015) of NPP. During this period, both the estimated annual total and the summer monthly maximum pan-Arctic NPP increased by about 47%. Positive monthly anomalies in NPP are highly correlated with positive anomalies in open water area during the summer months. Following the earlier ice retreat, the start of the high-productivity season has become earlier, e.g. at a mean rate of −3.0 d yr −1 in the northern Barents Sea, and the length of the high-productivity period has increased from 15 days in 1998 to 62 days in 2015. While in some areas, the termination of the productive season has been extended, owing to delayed ice formation, the termination has also become earlier in other areas, likely owing to limited nutrients.

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Mechanisms influencing seasonal-to-interannual prediction skill of sea ice extent in the Arctic Ocean in MIROC

10.5194/tc-2017-122 ◽

2017 ◽

Author(s):

Jun Ono ◽

Hiroaki Tatebe ◽

Yoshiki Komuro ◽

Masato I. Nodzu ◽

Masayoshi Ishii

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Barents Sea ◽

Heat Content ◽

The Arctic ◽

Subsurface Water ◽

Lead Times ◽

Sea Ice Concentration ◽

Sea Ice Extent ◽

The Arctic Ocean

Abstract. To assess the skill of predictions of the seasonal-to-interannual detrended sea ice extent in the Arctic Ocean (SIEAO) and to clarify the underlying physical processes, we conducted ensemble hindcasts, started on January 1st, April 1st, July 1st, and October 1st for each year from 1980 to 2011, for lead times of up three years, using the Model for Interdisciplinary Research on Climate (MIROC) version 5 initialized with the observed atmosphere and ocean anomalies and sea ice concentration. Significant skill is found for the winter months: the December SIEAO can be predicted up to 1 year ahead. This skill is attributed to the subsurface ocean heat content originating in the North Atlantic. The subsurface water flows into the Barents Sea from spring to fall and emerges at the surface in winter by vertical mixing, and eventually affects the sea ice variability there. Meanwhile, the September SIEAO predictions are skillful for lead times of up to 3 months, due to the persistence of sea ice in the Beaufort, Chukchi, and East Siberian Seas initialized in July, as suggested by previous studies.

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Arctic freshwater fluxes: sources, tracer budgets and inconsistencies

The Cryosphere ◽

10.5194/tc-13-2111-2019 ◽

2019 ◽

Vol 13 (8) ◽

pp. 2111-2131

Author(s):

Alexander Forryan ◽

Sheldon Bacon ◽

Takamasa Tsubouchi ◽

Sinhué Torres-Valdés ◽

Alberto C. Naveira Garabato

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Inorganic Nutrients ◽

The Arctic ◽

Freshwater Flux ◽

Geochemical Tracers ◽

Ice Melt ◽

Boundary Velocity ◽

The Arctic Ocean ◽

Geochemical Method

Abstract. The net rate of freshwater input to the Arctic Ocean has been calculated in the past by two methods: directly, as the sum of precipitation, evaporation and runoff, an approach hindered by sparsity of measurements, and by the ice and ocean budget method, where the net surface freshwater flux within a defined boundary is calculated from the rate of dilution of salinity, comparing ocean inflows with ice and ocean outflows. Here a third method is introduced, the geochemical method, as a modification of the budget method. A standard approach uses geochemical tracers (salinity, oxygen isotopes, inorganic nutrients) to compute “source fractions” that quantify a water parcel's constituent proportions of seawater, freshwater of meteoric origin, and either sea ice melt or brine (from the freezing-out of sea ice). The geochemical method combines the source fractions with the boundary velocity field of the budget method to quantify the net flux derived from each source. Here it is shown that the geochemical method generates an Arctic Ocean surface freshwater flux, which is also the meteoric source flux, of 200±44 mSv (1 Sv=106 m3 s−1), statistically indistinguishable from the budget method's 187±44 mSv, so that two different approaches to surface freshwater flux calculation are reconciled. The freshwater export rate of sea ice (40±14 mSv) is similar to the brine export flux, due to the “freshwater deficit” left by the freezing-out of sea ice (60±50 mSv). Inorganic nutrients are used to define Atlantic and Pacific seawater categories, and the results show significant non-conservation, whereby Atlantic seawater is effectively “converted” into Pacific seawater. This is hypothesized to be a consequence of denitrification within the Arctic Ocean, a process likely becoming more important with seasonal sea ice retreat. While inorganic nutrients may now be delivering ambiguous results on seawater origins, they may prove useful to quantify the Arctic Ocean's net denitrification rate. End point degeneracy is also discussed: multiple property definitions that lie along the same “mixing line” generate confused results.

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Atmospheric and oceanic drivers of regional Arctic winter sea-ice variability in present and future climates

10.5194/egusphere-egu21-2231 ◽

2021 ◽

Author(s):

Jakob Dörr ◽

Marius Årthun ◽

Tor Eldevik ◽

Erica Madonna

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Heat Transport ◽

Barents Sea ◽

Arctic Sea Ice ◽

The Arctic ◽

Ocean Heat Transport ◽

The Pacific ◽

Arctic Sea ◽

The Arctic Ocean

The recent retreat of Arctic sea ice area is overlaid by strong internal variability on all timescales. In winter, sea ice retreat and variability are currently dominated by the Barents Sea, primarily driven by variable ocean heat transport from the Atlantic. Climate models from the latest intercomparison project CMIP6 project that the future loss of winter Arctic sea ice spreads throughout the Arctic Ocean and, hence, that other regions of the Arctic Ocean will see increased sea-ice variability. It is, however, not known how the influence of ocean heat transport will change, and to what extent and in which regions other drivers, such as atmospheric circulation or river runoff into the Arctic Ocean, will become important. Using a combination of observations and simulations from the Community Earth System Model Large Ensemble (CESM-LE), we analyze and contrast the present and future regional drivers of the variability of the winter Arctic sea ice cover. We find that for the recent past, both observations and CESM-LE show that sea ice variability in the Atlantic and Pacific sector of the Arctic Ocean is influenced by ocean heat transport through the Barents Sea and Bering Strait, respectively. The two dominant modes of large-scale atmospheric variability &#8211; the Arctic Oscillation and the Pacific North American pattern &#8211; are only weakly related to recent regional sea ice variability. However, atmospheric circulation anomalies associated with regional sea ice variability show distinct patterns for the Atlantic and Pacific sectors consistent with heat and humidity transport from lower latitudes. In the future, under a high emission scenario, CESM-LE projects a gradual expansion of the footprint of the Pacific and Atlantic inflows, covering the whole Arctic Ocean by 2050-2079. This study highlights the combined importance of future Atlantification and Pacification of the Arctic Ocean and improves our understanding of internal climate variability which essential in order to predict future sea ice changes under anthropogenic warming.&#160; &#160;&#160;

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