Sea Ice Crossing by Migrating Caribou, <em>Rangifer tarandus</em>, in Northwestern Alaska
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Long movements across sea ice by Caribou (Rangifer tarandus) in Alaska are relatively uncommon and are not well documented. With rapidly diminishing sea ice cover in arctic waters, these movements may cease altogether. On 26 May 2012, a Caribou crossed a long span (57 km) of sea ice off the coast of Alaska. The cow successfully crossed after traveling 66 km on the sea ice and eventually reached the calving grounds. The highly dynamic nature of sea ice, which is driven by oceanic currents and wind during spring break-up, presents inherent hazards different from lake ice. Based on three years of Global Positioning System (GPS) radio-collar data, Caribou routinely crossed long expanses (30 km) of ice covering the brackish Selawik Lake and shorter stretches (<13 km) on Inland Lake during their spring migration north. There was also a single crossing on the ice covering Selawik Lake during the fall migration south to the wintering grounds that took place in early November 2010. Five GPS-collared Caribou crossed the short frozen span (14 km) of Kotzebue Sound between Cape Krusenstern National Monument and the Baldwin Peninsula in the fall of 2011.Keywords:
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During the summer 1987 expedition of the polar research vessel'Polarstern'in the Eurasian Basin of the Arctic Ocean, sea ice at about 84-86°N and 20-30°E was found to have high concentrations of particulate material. The particle-laden ice occurred in patches which often darkened more than half the ice surface at our northernmost positions. Much of this ice appeared to be within the Siberian Branch of the Transpolar Drift stream, which transports deformed, multi-year ice from the Siberian shelves westward across the Eurasian Basin. Lithogenic sediment, which is the major component of the particulate material, may have been incorporated during ice formation on the shallow Siberian seas. Diatoms collected from the particle-rich ice surfaces support this conclusion, as assemblages were dominated by a marine benthic species similar to that reported from sea ice off the coast of northeast Siberia. Based on drift trajectories of buoys deployed on the ice it appears that much of the particle-laden ice exited the Arctic Ocean through the Fram Strait and joined the East Greenland Current. Very different sea ice characteristics were found east of the Yermak Plateau and north of Svalbard and Frans Josef Land up to about 83-84°N. Here sea ice was thinner, less deformed, with lower amounts of lithogenic sediment and diatoms. The diatom assemblage was dominated by planktonic freshwater species. Trajectories of buoys deployed on sea ice in this region indicated a tendency for southward transport to the Yermak Plateau or into the Barents Sea.
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Abstract In this study the mechanisms for low-frequency variability of summer Arctic sea ice are analyzed using long control simulations from three coupled models (GFDL CM2.1, GFDL CM3, and NCAR CESM). Despite different Arctic sea ice mean states, there are many robust features in the response of low-frequency summer Arctic sea ice variability to the three key predictors (Atlantic and Pacific oceanic heat transport into the Arctic and the Arctic dipole) across all three models. In all three models, an enhanced Atlantic (Pacific) heat transport into the Arctic induces summer Arctic sea ice decline and surface warming, especially over the Atlantic (Pacific) sector of the Arctic. A positive phase of the Arctic dipole induces summer Arctic sea ice decline and surface warming on the Pacific side, and opposite changes on the Atlantic side. There is robust Bjerknes compensation at low frequency, so the northward atmospheric heat transport provides a negative feedback to summer Arctic sea ice variations. The influence of the Arctic dipole on summer Arctic sea ice extent is more (less) effective in simulations with less (excessive) climatological summer sea ice in the Atlantic sector. The response of Arctic sea ice thickness to the three key predictors is stronger in models that have thicker climatological Arctic sea ice.
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Arctic dipole anomaly
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Sea ice concentration
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Abstract Uncertainties in the timing of a seasonal ice cover in the Arctic Ocean depend on model physics and parameterizations, natural variability at decadal timescales and uncertainties in climate scenarios and forcings. We use the Gridded Monthly Sea-Ice Extent and Concentration, 1850 Onward product to assess the simulated decadal variability from the Community Earth System Model – Large Ensemble (CESM-LE) in the Pacific, Eurasian and Atlantic sector of the Arctic where a longer observational record exists. Results show that sea-ice decadal (8-16 years) variability in CESM-LE is in agreement with the observational record in the Pacific sector of the Arctic, underestimated in the Eurasian sector of the Arctic, specifically in the East-Siberian Sea, and slightly overestimated in the Atlantic sector of the Arctic, specifically in the Greenland Sea. Results also show an increase in variability at decadal timescales in the Eurasian and Pacific sectors during the transition to a seasonally ice-free Arctic, in agreement with the observational record although this increase is delayed by 10-20 years. If the current sea-ice retreat in the Arctic continues to be Pacific-centric, results from the CESM-LE suggest that uncertainty in the timing of an ice-free Arctic associated with natural variability is realistic, but that a seasonal ice cover may occur earlier than projected.
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This study quantifies drastic variations of Arctic sea ice during 2000–2020. Four dominant modes revealed 32.18%, 14.6%, 9.34% and 8.25% of the total variance of sea ice concentration over the Arctic. The first two dominant modes have exhibited seesaw structures on the Atlantic and Pacific sectors of the Arctic over the past 20 years: Sea ice increased in the southwest of Greenland and reduced in the northeast; sea ice decreased drastically in the Bering Sea but increased in the Okhotsk Sea. An overall increase of sea ice in the Arctic occurred in the third dominant mode, while a seesaw structure appeared in the Barents Sea in the fourth dominant mode. At the end, the influence of the Arctic atmosphere and upper-ocean state on the Arctic sea ice variation was investigated.
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<p>SODA (Simple Ocean Data Assimilation) is one of the ocean reanalysis data widely used in oceanographic research. The SODA3 dataset provides multiple ocean reanalysis data sets driven by different atmospheric forcing fields. The differences between their arctic sea ice simulations are assessed and compared with observational data from different sources. We find that in the simulation of arctic sea ice concentration, the differences between SODA3 reanalysis data sets driven by different forcing fields are small, showing a low concentration of thick ice and a high concentration of thin ice. In terms of sea ice extent, different forced field model data can well simulate the decline trend of observed data, but the overall arctic sea ice extent is overestimated, which is related to more simulated sea ice in the sea ice margin. In terms of the simulation of arctic sea ice thickness, the results of different forcing fields show that the simulation of arctic sea ice thickness by SODA data set is relatively thin on the whole, especially in the thick ice region. The results of different models differ greatly in the Beaufort Sea, the Fram Strait, and the Central Arctic Sea. The above differences may be related to the differences between the model-driven field and the actual wind field, which leads to the inaccurate simulation of arctic sea ice transport and ultimately to the different thickness distribution simulation. In addition, differences in heat flux may also lead to differences in arctic sea ice between models and observations. In this paper, the differences between the results of arctic sea ice driven by different SODA3 forcing fields are studied, which provides a reference for the use of SODA3 data in the study of arctic sea ice and guidance for the selection of SODA data in the study of sea ice in different arctic seas.</p>
Sea ice concentration
Arctic geoengineering
Forcing (mathematics)
Lead (geology)
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Abstract : The oceanic fluxes of volume, heat, and freshwater through the Bering Strait, the only oceanic input to the Arctic from the Pacific, are critical to the water properties of the Chukchi Sea, act as a trigger of sea-ice melt in the Chukchi, provide a subsurface source of heat to the Arctic in winter (with possible impacts on sea-ice), and are a major component of freshwater input to the Arctic (Figures 1 and 2). Quantification of these fluxes (which all vary significantly seasonally and interannually) is critical to understanding the physics of the western Arctic, including sea-ice retreat timing and patterns, and possibly sea-ice thickness. Recent data [Woodgate et al., 2012] show a 50% increase in the Bering Strait fluxes from 2001 to 2011 (Figure 2), and indicate that remote-sensed data are insufficient to assess the interannual variability in the throughflow and that year-round in situ moorings are currently the only effective way of quantifying the oceanic fluxes of volume, heat and freshwater from the Pacific to the Arctic.
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The study revealed the unique features of winter sea ice dynamics in the Canadian Arctic during 1974–1978 winter seasons. The features included the presence of open water and thin ice in parts of Smith Sound, northern Baffin Bay, western Jones Sound, Foxe Basin, Lancaster Sound, and southeast Baffin Bay. In addition, persistency of leads and polynyas at Smith Sound, Melville Bay, northern Lancaster Sound, Jones Sound, Home Bay, eastern Beaufort Sea, and Amundsen Gulf was remarkable phenomenon. Further, active leads were found in Baffin Bay and Beaufort Sea throughout the winter season. Two ice dams at Smith Sound and Barrow Strait regulated the influx of ice into northern Baffin Bay. The influx of ice into northern Baffin Bay through Smith Sound, Jones Sound, and Lancaster Sound estimated to be 654 km 3 per year, whereas the influx of ice from the Arctic Ocean and the Central Archipelago through Robeson Channel, Fram Sound, and Barrow Strait was about 201 km 3 per year.
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Abstract Canada’s IPY program funded seven marine projects spanning the North American Arctic. Work embraced oceanography, air-sea interactions, storm response, paleo-climate and trace-element chemistry. Notable findings are emerging. Conditions in the Beaufort were unusual in 2007, with very high air pressure bringing strong winds, rapid ice drift, thin winter ice, enhanced shelf-break upwelling and a maximum in freshwater retention in the Beaufort Gyre. A mapping of trace chemicals suggests that Arctic mid-depth circulation may also have reversed. Study of Canadian Arctic through-flow revealed a net annual seawater export of 44,000 cubic kilometres from the Arctic to Baffin Bay. Observations of sea ice, sustained through the IPY, affirmed that ice cover is the key attribute of Arctic seas, with wind as a potent agent in its variation. Surveys have shown that the anthropogenic decline in seawater alkalinity is aggravated in the Arctic by low temperature and low salinity resulting from ice melt. Careful experiments have revealed that Arctic phytoplankton growth is constrained by scarcity of dissolved iron where light levels are low. A manganese fingerprint in sediments has tracked changing sea level during the Ice Age. Sediment-core analysis has revealed the Arctic Oscillation as a dominant cause of long-period climate variations during the Holocene. One project has demonstrated how multi-tasked vessels can maintain a watch on Canada’s Arctic within a reliable affordable logistic framework, while a wave forecast model developed by another for the Beaufort is suitable for operational use.
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Arctic ecology
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