scholarly journals Central Arctic Ocean paleoceanography from ~ 50 ka to present, on the basis of ostracode faunal assemblages from SWERUS 2014 expedition

2017 ◽  
Author(s):  
Laura Gemery ◽  
Thomas M. Cronin ◽  
Robert K. Poirier ◽  
Christof Pearce ◽  
Natalia Barrientos ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Large Scale ◽  
Late Quaternary ◽  
Atlantic Water ◽  
Environmental Indicators ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Central Arctic Ocean ◽  
Ice Conditions

Abstract. Late Quaternary paleoceanographic changes in the central Arctic Ocean were reconstructed from a multicore and gravity core from the Lomonosov Ridge (Arctic Ocean) collected during the 2014 SWERUS-C3 Expedition. Ostracode assemblages dated by accelerator mass spectrometry (AMS) indicate changing sea-ice conditions and warm Atlantic Water (AW) inflow to the Arctic Ocean from ~ 50 ka to present. Key taxa used as environmental indicators include Acetabulastoma arcticum (perennial sea ice), Polycope spp. (productivity and sea ice), Krithe hunti (partially sea-ice free conditions, deep water inflow), and Rabilimis mirabilis (high nutrient, AW inflow). Results indicate seasonally sea-ice free conditions during Marine Isotope Stage (MIS) 3 (~ 57–29 ka), rapid deglacial changes in water mass conditions (15–11 ka), seasonally sea-ice free conditions during the early Holocene (~ 10–7 ka) and perennial sea ice during the late Holocene. Comparisons with faunal records from other cores from the Mendeleev and Lomonosov Ridges suggest generally similar patterns, although sea-ice cover during the last glacial maximum may have been less extensive at the southern Lomonosov Ridge at our core site (~ 85.15° N, 152° E) than farther north and towards Greenland. The new data also provide evidence for abrupt, large-scale shifts in ostracode species depth and geographical distributions during rapid climatic transitions.

scholarly journals Central Arctic Ocean paleoceanography from  ∼  50 ka to present, on the basis of ostracode faunal assemblages from the SWERUS 2014 expedition

2017 ◽  
Vol 13 (11) ◽  
pp. 1473-1489 ◽  
Author(s):  
Laura Gemery ◽  
Thomas M. Cronin ◽  
Robert K. Poirier ◽  
Christof Pearce ◽  
Natalia Barrientos ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Large Scale ◽  
Water Mass ◽  
Late Quaternary ◽  
High Surface ◽  
Environmental Indicators ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Central Arctic Ocean

Abstract. Late Quaternary paleoceanographic changes at the Lomonosov Ridge, central Arctic Ocean, were reconstructed from a multicore and gravity core recovered during the 2014 SWERUS-C3 Expedition. Ostracode assemblages dated by accelerator mass spectrometry (AMS) indicate changing sea-ice conditions and warm Atlantic Water (AW) inflow to the Arctic Ocean from  ∼  50 ka to present. Key taxa used as environmental indicators include Acetabulastoma arcticum (perennial sea ice), Polycope spp. (variable sea-ice margins, high surface productivity), Krithe hunti (Arctic Ocean deep water), and Rabilimis mirabilis (water mass change/AW inflow). Results indicate periodic seasonally sea-ice-free conditions during Marine Isotope Stage (MIS) 3 ( ∼  57–29 ka), rapid deglacial changes in water mass conditions (15–11 ka), seasonally sea-ice-free conditions during the early Holocene ( ∼  10–7 ka) and perennial sea ice during the late Holocene. Comparisons with faunal records from other cores from the Mendeleev and Lomonosov ridges suggest generally similar patterns, although sea-ice cover during the Last Glacial Maximum may have been less extensive at the new Lomonosov Ridge core site ( ∼  85.15° N, 152° E) than farther north and towards Greenland. The new data provide evidence for abrupt, large-scale shifts in ostracode species depth and geographical distributions during rapid climatic transitions.

scholarly journals Arctic Ocean sea ice snow depth evaluation and bias sensitivity in CCSM

2013 ◽  
Vol 7 (2) ◽  
pp. 1495-1532 ◽  
Author(s):  
B. A. Blazey ◽  
M. M. Holland ◽  
E. C. Hunke
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Large Scale ◽  
System Model ◽  
Arctic Climate ◽  
The Arctic ◽  
Blowing Snow ◽  
Climate System Model ◽  
The Arctic Ocean ◽  
Ice Conditions

Abstract. Sea ice cover in the Arctic Ocean is a continued focus of attention. This study assesses the capability of hindcast simulations of the Community Climate System Model (CCSM) to reproduce observed snow depths and densities overlying the Arctic Ocean sea ice. The model is evaluated using measurements provided by historic Russian polar drift stations. Following the identification of seasonal biases produced in the simulations, the thermodynamic transfer through the snow – ice column is perturbed to determine model sensitivity to these biases. This study concludes that perturbations on the order of the observed biases result in modification of the annual mean conductive flux of 0.5 W m−2 relative to an unmodified simulation. The results suggest that the ice has a complex response to snow characteristics, with ice of different thicknesses producing distinct reactions. Consequently, we suggest that the inclusion of additional snow evolution processes such as blowing snow, densification, and seasonal changes in snow conductivity in sea ice models would increase the fidelity of the model with respect to the physical system. Moreover, our results suggest that simulated high latitude precipitation biases have important effects on the simulated ice conditions, resulting in impacts on the Arctic climate in general in large-scale climate.

scholarly journals On large-scale shifts in the Arctic Ocean and sea-ice conditions during 1979−98

2001 ◽  
Vol 33 ◽  
pp. 545-550 ◽  
Author(s):  
W. Maslowski ◽  
D. C. Marble ◽  
W. Walczowski ◽  
A. J. Semtner
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Fresh Water ◽  
Ocean Circulation ◽  
Large Scale ◽  
Atlantic Water ◽  
The Arctic ◽  
Upper Ocean ◽  
Recent Climate ◽  
The Arctic Ocean

AbstractResults from a regional model of the Arctic Ocean and sea ice forced with realistic atmospheric data are analyzed to understand recent climate variability in the region. The primary simulation uses daily-averaged 1979 atmospheric fields repeated for 20 years and then continues with interannual forcing derived from the European Centre for Medium-range Weather Forecasts for 1979−98. An eastward shift in the ice-ocean circulation, fresh-water distribution and Atlantic Water extent has been determined by comparing conditions between the early 1980s and 1990s. A new trend is modeled in the late 1990s, and has a tendency to return the large-scale sea-ice and upper ocean conditions to their state in the early 1980s. Both the sea-ice and the upper ocean circulation as well as fresh-water export from the Russian shelves and Atlantic Water recirculation within the Eurasian Basin indicate that the Arctic climate is undergoing another shift. This suggests an oscillatory behavior of the Arctic Ocean system. Interannual atmospheric variability appears to be the main and sufficient driver of simulated changes. The ice cover acts as an effective dynamic medium for vorticity transfer from the atmosphere into the ocean.

scholarly journals Cryospheric Impacts of Soviet River Diversion Schemes

1984 ◽  
Vol 5 ◽  
pp. 61-68 ◽  
Author(s):  
T. Holt ◽  
P. M. Kelly ◽  
B. S. G. Cherry
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
River Discharge ◽  
Large Scale ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Ice Concentration ◽  
The Arctic Ocean ◽  
The Impact

Soviet plans to divert water from rivers flowing into the Arctic Ocean have led to research into the impact of a reduction in discharge on Arctic sea ice. We consider the mechanisms by which discharge reductions might affect sea-ice cover and then test various hypotheses related to these mechanisms. We find several large areas over which sea-ice concentration correlates significantly with variations in river discharge, supporting two particular hypotheses. The first hypothesis concerns the area where the initial impacts are likely to which is the Kara Sea. Reduced riverflow is associated occur, with decreased sea-ice concentration in October, at the time of ice formation. This is believed to be the result of decreased freshening of the surface layer. The second hypothesis concerns possible effects on the large-scale current system of the Arctic Ocean and, in particular, on the inflow of Atlantic and Pacific water. These effects occur as a result of changes in the strength of northward-flowing gradient currents associated with variations in river discharge. Although it is still not certain that substantial transfers of riverflow will take place, it is concluded that the possibility of significant cryospheric effects and, hence, large-scale climate impact should not be neglected.

scholarly journals Weakening of Cold Halocline Layer Exposes Sea Ice to Oceanic Heat in the Eastern Arctic Ocean

2020 ◽  
Vol 33 (18) ◽  
pp. 8107-8123 ◽  
Author(s):  
Igor V. Polyakov ◽  
Tom P. Rippeth ◽  
Ilker Fer ◽  
Matthew B. Alkire ◽  
Till M. Baumann ◽  
...  
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Mixed Layer ◽  
Winter Season ◽  
Atlantic Water ◽  
The Arctic ◽  
Surface Mixed Layer ◽  
Winter Convection ◽  
Oceanic Heat Flux

AbstractA 15-yr duration record of mooring observations from the eastern (>70°E) Eurasian Basin (EB) of the Arctic Ocean is used to show and quantify the recently increased oceanic heat flux from intermediate-depth (~150–900 m) warm Atlantic Water (AW) to the surface mixed layer and sea ice. The upward release of AW heat is regulated by the stability of the overlying halocline, which we show has weakened substantially in recent years. Shoaling of the AW has also contributed, with observations in winter 2017–18 showing AW at only 80 m depth, just below the wintertime surface mixed layer, the shallowest in our mooring records. The weakening of the halocline for several months at this time implies that AW heat was linked to winter convection associated with brine rejection during sea ice formation. This resulted in a substantial increase of upward oceanic heat flux during the winter season, from an average of 3–4 W m−2 in 2007–08 to >10 W m−2 in 2016–18. This seasonal AW heat loss in the eastern EB is equivalent to a more than a twofold reduction of winter ice growth. These changes imply a positive feedback as reduced sea ice cover permits increased mixing, augmenting the summer-dominated ice-albedo feedback.

The role of sea ice for plastic pollution in the Arctic

2021 ◽  
Author(s):  
Ilka Peeken ◽  
Elisa Bergami ◽  
Ilaria Corsi ◽  
Benedikt Hufnagl ◽  
Christian Katlein ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Long Range ◽  
Environmental Concern ◽  
Ice Cores ◽  
Atlantic Water ◽  
The Arctic ◽  
Polar Regions ◽  
Plastic Pollution ◽  
The Arctic Ocean

<p>Marine plastic pollution is a growing worldwide environmental concern as recent reports indicate that increasing quantities of litter disperse into secluded environments, including Polar Regions. Plastic degrades into smaller fragments under the influence of sunlight, temperature changes, mechanic abrasion and wave action resulting in small particles < 5mm called microplastics (MP). Sea ice cores, collected in the Arctic Ocean have so far revealed extremely high concentrations of very small microplastic particles, which might be transferred in the ecosystem with so far unknown consequences for the ice dependant marine food chain.  Sea ice has long been recognised as a transport vehicle for any contaminates entering the Arctic Ocean from various long range and local sources. The Fram Strait is hereby both, a major inflow gateway of warm Atlantic water, with any anthropogenic imprints and the major outflow region of sea ice originating from the Siberian shelves and carried via the Transpolar Drift. The studied sea ice revealed a unique footprint of microplastic pollution, which were related to different water masses and indicating different source regions. Climate change in the Arctic include loss of sea ice, therefore, large fractions of the embedded plastic particles might be released and have an impact on living systems. By combining modeling of sea ice origin and growth, MP particle trajectories in the water column as well as MPs long-range transport via particle tracking and transport models we get first insights  about the sources and pathways of MP in the Arctic Ocean and beyond and how this might affect the Arctic ecosystem.</p>

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 Natural variability of the Arctic Ocean sea ice during the present interglacial

2020 ◽  
Vol 117 (42) ◽  
pp. 26069-26075
Author(s):  
Anne de Vernal ◽  
Claude Hillaire-Marcel ◽  
Cynthia Le Duc ◽  
Philippe Roberge ◽  
Camille Brice ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Natural Variability ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
Arctic Sea ◽  
The Arctic Ocean ◽  
Open Question ◽  
The Impact

The impact of the ongoing anthropogenic warming on the Arctic Ocean sea ice is ascertained and closely monitored. However, its long-term fate remains an open question as its natural variability on centennial to millennial timescales is not well documented. Here, we use marine sedimentary records to reconstruct Arctic sea-ice fluctuations. Cores collected along the Lomonosov Ridge that extends across the Arctic Ocean from northern Greenland to the Laptev Sea were radiocarbon dated and analyzed for their micropaleontological and palynological contents, both bearing information on the past sea-ice cover. Results demonstrate that multiyear pack ice remained a robust feature of the western and central Lomonosov Ridge and that perennial sea ice remained present throughout the present interglacial, even during the climate optimum of the middle Holocene that globally peaked ∼6,500 y ago. In contradistinction, the southeastern Lomonosov Ridge area experienced seasonally sea-ice-free conditions, at least, sporadically, until about 4,000 y ago. They were marked by relatively high phytoplanktonic productivity and organic carbon fluxes at the seafloor resulting in low biogenic carbonate preservation. These results point to contrasted west–east surface ocean conditions in the Arctic Ocean, not unlike those of the Arctic dipole linked to the recent loss of Arctic sea ice. Hence, our data suggest that seasonally ice-free conditions in the southeastern Arctic Ocean with a dominant Arctic dipolar pattern, may be a recurrent feature under “warm world” climate.

Eddy statistics validation of an ORCA12 ocean and sea ice model for the Arctic with satellite data

2020 ◽  
Author(s):  
Stefanie Rynders ◽  
Yevgeny Akesenov ◽  
Igor Kozlov
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Large Scale ◽  
Mixed Layer Depth ◽  
Three Dimensional ◽  
The Arctic ◽  
The European Union ◽  
Boundary Current ◽  
Horizon 2020 ◽  
The Uk

<p>As sea ice and ocean models are moving to higher resolution it becomes possible to permit eddy formation even in the Arctic Ocean. Eddies can affect the three dimensional ocean state through causing mixing and even ventilation of subsurface ocean layers if they are deep enough. To ensure models have the potential to simulate the density structure correctly it is therefore necessary to start doing model validation of not only the large scale ocean state, but also of the eddy field. Eddy statistics for the Arctic are available from satellite for the Western Arctic Ocean and the Fram Strait, in particular on number, size and cyclonicity of eddies for open ocean versus ice covered sites. These are compared to a NEMO-LIM 1/12 degree sea ice and ocean simulation (resolution 2-5km), upon which the model based statistics are expanded to the whole Arctic. In the model it is also possible to examine the depth structure of eddies, allowing to generate size vs. depth statistics. This, together with climatological mixed layer depth, provides a first estimate to get satellite-based information on mixing from eddies in the Arctic. We also map the maximum depth of eddies, to examine ventilation and identify sites with especially deep eddies, for instance at the boundary current. Acknowledgements: Grant NE/R000654/1 “Towards a Marginal Sea Ice Cover” funded by the UK Natural Research Council (NERC) and the UK-Russia Arctic bursaries program funded by the United Kingdom’s Department for Business, Energy and Industrial Strategy. The study is also supported from the project “The Advective Pathways of nutrients and key Ecological substances in the Arctic (APEAR)” (grant NE/R012865/1) funded by the Joint UK NERC/German Federal Ministry of Education and Research Changing Arctic Ocean Programme. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 821926 (IMMERSE). IK acknowledges the support from RFBR grant No 18-35-20078.</p>

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