Artículos de revistas: "Gyre de Beaufort"

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Meneghello, Gianluca, Edward Doddridge, John Marshall, Jeffery Scott y Jean-Michel Campin. "Exploring the Role of the “Ice–Ocean Governor” and Mesoscale Eddies in the Equilibration of the Beaufort Gyre: Lessons from Observations". Journal of Physical Oceanography 50, n.º 1 (enero de 2020): 269–77. http://dx.doi.org/10.1175/jpo-d-18-0223.1.

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AbstractObservations of Ekman pumping, sea surface height anomaly, and isohaline depth anomaly over the Beaufort Gyre are used to explore the relative importance and role of (i) feedbacks between ice and ocean currents, dubbed the “ice–ocean governor,” and (ii) mesoscale eddy processes in the equilibration of the Beaufort Gyre. A two-layer model of the gyre is fit to observations and used to explore the mechanisms governing the gyre evolution from the monthly to the decennial time scale. The ice–ocean governor dominates the response on interannual time scales, with eddy processes becoming evident only on the longest, decadal time scales.

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2

Meneghello, Gianluca, John Marshall, Mary-Louise Timmermans y Jeffery Scott. "Observations of Seasonal Upwelling and Downwelling in the Beaufort Sea Mediated by Sea Ice". Journal of Physical Oceanography 48, n.º 4 (abril de 2018): 795–805. http://dx.doi.org/10.1175/jpo-d-17-0188.1.

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AbstractWe present observational estimates of Ekman pumping in the Beaufort Gyre region. Averaged over the Canada Basin, the results show a 2003–14 average of 2.3 m yr−1 downward with strong seasonal and interannual variability superimposed: monthly and yearly means range from 30 m yr−1 downward to 10 m yr−1 upward. A clear, seasonal cycle is evident with intense downwelling in autumn and upwelling during the winter months, despite the wind forcing being downwelling favorable year-round. Wintertime upwelling is associated with friction between the large-scale Beaufort Gyre ocean circulation and the surface ice pack and contrasts with previous estimates of yearlong downwelling; as a consequence, the yearly cumulative Ekman pumping over the gyre is significantly reduced. The spatial distribution of Ekman pumping is also modified, with the Beaufort Gyre region showing alternating, moderate upwelling and downwelling, while a more intense, yearlong downwelling averaging 18 m yr−1 is identified in the northern Chukchi Sea region. Implications of the results for understanding Arctic Ocean dynamics and change are discussed.

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3

Manucharyan, Georgy E., Michael A. Spall y Andrew F. Thompson. "A Theory of the Wind-Driven Beaufort Gyre Variability". Journal of Physical Oceanography 46, n.º 11 (noviembre de 2016): 3263–78. http://dx.doi.org/10.1175/jpo-d-16-0091.1.

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AbstractThe halocline of the Beaufort Gyre varies significantly on interannual to decadal time scales, affecting the freshwater content (FWC) of the Arctic Ocean. This study explores the role of eddies in the Ekman-driven gyre variability. Following the transformed Eulerian-mean paradigm, the authors develop a theory that links the FWC variability to the stability of the large-scale gyre, defined as the inverse of its equilibration time. The theory, verified with eddy-resolving numerical simulations, demonstrates that the gyre stability is explicitly controlled by the mesoscale eddy diffusivity. An accurate representation of the halocline dynamics requires the eddy diffusivity of 300 ± 200 m2 s−1, which is lower than what is used in most low-resolution climate models. In particular, on interannual and longer time scales the eddy fluxes and the Ekman pumping provide equally important contributions to the FWC variability. However, only large-scale Ekman pumping patterns can significantly alter the FWC, with spatially localized perturbations being an order of magnitude less efficient. Lastly, the authors introduce a novel FWC tendency diagnostic—the Gyre Index—that can be conveniently calculated using observations located only along the gyre boundaries. Its strong predictive capabilities, assessed in the eddy-resolving model forced by stochastic winds, suggest that the Gyre Index would be of use in interpreting FWC evolution in observations as well as in numerical models.

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4

Zhong, Wenli y Jinping Zhao. "Deepening of the Atlantic Water Core in the Canada Basin in 2003–11". Journal of Physical Oceanography 44, n.º 9 (1 de septiembre de 2014): 2353–69. http://dx.doi.org/10.1175/jpo-d-13-084.1.

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Abstract In 2004, a cold mode of Atlantic Water (AW) entered the western Canada basin, replacing the anomalously warm AW that resided in the basin since the 1990s. This slightly colder AW was denser than the 1990s warm mode; it gradually filled most of the western basin by 2009. The enhanced surface stress curl led to the spinup of the Beaufort Gyre and convergence of freshwater. The spinup also resulted in a deepening of the AW core at the center of the gyre and in shoaling of the AW core at the margins of the gyre. The density versus depth relationship revealed in this study shows that the depth of the maximum AW temperature was mainly controlled by the density structure before 2007; thus, it is the case when the denser water was deeper and the case when the lighter water was shallower around the basin. However, this relationship was reversed to become the case when the denser water was shallower and the case when the lighter water was deeper since 2008 inside the Beaufort Gyre. The combined effect of density and sea ice retreat that enhanced surface stress curl determined the depth of the AW inside the Beaufort Gyre since 2008. The deepening of the AW core and expanding of the area where the AW deepening occurred had a profound effect on the large-scale circulation in the Arctic Ocean.

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5

Davis, Peter E. D., Camille Lique y Helen L. Johnson. "On the Link between Arctic Sea Ice Decline and the Freshwater Content of the Beaufort Gyre: Insights from a Simple Process Model". Journal of Climate 27, n.º 21 (24 de octubre de 2014): 8170–84. http://dx.doi.org/10.1175/jcli-d-14-00090.1.

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Abstract Recent satellite and hydrographic observations have shown that the rate of freshwater accumulation in the Beaufort Gyre of the Arctic Ocean has accelerated over the past decade. This acceleration has coincided with the dramatic decline observed in Arctic sea ice cover, which is expected to modify the efficiency of momentum transfer into the upper ocean. Here, a simple process model is used to investigate the dynamical response of the Beaufort Gyre to the changing efficiency of momentum transfer, and its link with the enhanced accumulation of freshwater. A linear relationship is found between the annual mean momentum flux and the amount of freshwater accumulated in the Beaufort Gyre. In the model, both the response time scale and the total quantity of freshwater accumulated are determined by a balance between Ekman pumping and an eddy-induced volume flux toward the boundary, highlighting the importance of eddies in the adjustment of the Arctic Ocean to a change in forcing. When the seasonal cycle in the efficiency of momentum transfer is modified (but the annual mean momentum flux is held constant), it has no effect on the accumulation of freshwater, although it does impact the timing and amplitude of the annual cycle in Beaufort Gyre freshwater content. This suggests that the decline in Arctic sea ice cover may have an impact on the magnitude and seasonality of the freshwater export into the North Atlantic.

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6

Regan, Heather, Camille Lique, Claude Talandier y Gianluca Meneghello. "Response of Total and Eddy Kinetic Energy to the Recent Spinup of the Beaufort Gyre". Journal of Physical Oceanography 50, n.º 3 (marzo de 2020): 575–94. http://dx.doi.org/10.1175/jpo-d-19-0234.1.

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AbstractThe Beaufort Gyre in the Arctic Ocean has spun up over the past two decades in response to changes of the wind forcing and sea ice conditions, accumulating a significant amount of freshwater. Here a simulation performed with a high-resolution, eddy-resolving model is analyzed in order to provide a detailed description of the total and eddy kinetic energy and their response to this spinup of the gyre. On average, and in contrast to the typical open ocean conditions, the levels of mean and eddy kinetic energy are of the same order of magnitude, and the eddy kinetic energy is only intensified along the boundary and in the subsurface. In response to the strong anomalous atmospheric conditions in 2007, the gyre spins up and the mean kinetic energy almost doubles, while the eddy kinetic energy does not increase significantly for a long time period. This is because the isopycnals are able to flatten and the gyre expands outwards, reducing the potential for baroclinic instability. These results have implications for understanding the mechanisms at play for equilibrating the Beaufort Gyre and the variability and future changes of the Arctic freshwater system.

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7

Plueddemann, A. J., R. Krishfield, T. Takizawa, K. Hatakeyama y S. Honjo. "Upper ocean velocities in the Beaufort Gyre". Geophysical Research Letters 25, n.º 2 (15 de enero de 1998): 183–86. http://dx.doi.org/10.1029/97gl53638.

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8

Vazquez, Heriberto J., Bruce D. Cornuelle, Peter F. Worcester y Matthew Dzieciuch. "Ocean acoustic tomography in the Beaufort Gyre". Journal of the Acoustical Society of America 152, n.º 4 (octubre de 2022): A110. http://dx.doi.org/10.1121/10.0015713.

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An ocean acoustic tomography array with a radius of 150 km was installed in the central Beaufort Gyre during 2016–2017 for the Canada Basin Acoustic Propagation Experiment (CANAPE). Five transceivers were deployed in a pentagon shape with a sixth transceiver at the center and a long vertical receiving array northwest of the central mooring. At least 12 refracted-surface-reflected (RSR) ray arrivals with lower turning points at depths between 500 and 3500 m were resolved in the acoustic receptions at all receivers. Travel-time anomalies were computed relative to a range-dependent sound-speed reference made by objectively interpolating annual-average sound-speed profiles constructed from the temperature data at each mooring. The travel time anomalies were inverted to estimate the 3-D sound-speed anomaly, including corrections to the positions of sources and receivers consistent with the uncertainty from long-baseline acoustic navigation systems at each mooring. Although the deep water in the Canada Basin is nearly homogeneous in temperature and salinity and highly stable (slowly warming in response to geothermal heating), it proved necessary to allow for a sound-speed change in the deep ocean to obtain consistent inversions, suggesting that the sound-speed equation at high pressure and low temperature is in error by about 0.1–0.2 ms−1.

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9

Armitage, Thomas W. K., Sheldon Bacon, Andy L. Ridout, Alek A. Petty, Steven Wolbach y Michel Tsamados. "Arctic Ocean surface geostrophic circulation 2003–2014". Cryosphere 11, n.º 4 (26 de julio de 2017): 1767–80. http://dx.doi.org/10.5194/tc-11-1767-2017.

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Abstract. Monitoring the surface circulation of the ice-covered Arctic Ocean is generally limited in space, time or both. We present a new 12-year record of geostrophic currents at monthly resolution in the ice-covered and ice-free Arctic Ocean derived from satellite radar altimetry and characterise their seasonal to decadal variability from 2003 to 2014, a period of rapid environmental change in the Arctic. Geostrophic currents around the Arctic basin increased in the late 2000s, with the largest increases observed in summer. Currents in the southeastern Beaufort Gyre accelerated in late 2007 with higher current speeds sustained until 2011, after which they decreased to speeds representative of the period 2003–2006. The strength of the northwestward current in the southwest Beaufort Gyre more than doubled between 2003 and 2014. This pattern of changing currents is linked to shifting of the gyre circulation to the northwest during the time period. The Beaufort Gyre circulation and Fram Strait current are strongest in winter, modulated by the seasonal strength of the atmospheric circulation. We find high eddy kinetic energy (EKE) congruent with features of the seafloor bathymetry that are greater in winter than summer, and estimates of EKE and eddy diffusivity in the Beaufort Sea are consistent with those predicted from theoretical considerations. The variability of Arctic Ocean geostrophic circulation highlights the interplay between seasonally variable atmospheric forcing and ice conditions, on a backdrop of long-term changes to the Arctic sea ice–ocean system. Studies point to various mechanisms influencing the observed increase in Arctic Ocean surface stress, and hence geostrophic currents, in the 2000s – e.g. decreased ice concentration/thickness, changing atmospheric forcing, changing ice pack morphology; however, more work is needed to refine the representation of atmosphere–ice–ocean coupling in models before we can fully attribute causality to these increases.

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10

Morison, James, Ron Kwok, Suzanne Dickinson, Roger Andersen, Cecilia Peralta-Ferriz, David Morison, Ignatius Rigor, Sarah Dewey y John Guthrie. "The Cyclonic Mode of Arctic Ocean Circulation". Journal of Physical Oceanography 51, n.º 4 (abril de 2021): 1053–75. http://dx.doi.org/10.1175/jpo-d-20-0190.1.

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AbstractArctic Ocean surface circulation change should not be viewed as the strength of the anticyclonic Beaufort Gyre. While the Beaufort Gyre is a dominant feature of average Arctic Ocean surface circulation, empirical orthogonal function analysis of dynamic height (1950–89) and satellite altimetry–derived dynamic ocean topography (2004–19) show the primary pattern of variability in its cyclonic mode is dominated by a depression of the sea surface and cyclonic surface circulation on the Russian side of the Arctic Ocean. Changes in surface circulation after Arctic Oscillation (AO) maxima in 1989 and 2007–08 and after an AO minimum in 2010 indicate the cyclonic mode is forced by the AO with a lag of about 1 year. Associated with a one standard deviation increase in the average AO starting in the early 1990s, Arctic Ocean surface circulation underwent a cyclonic shift evidenced by increased spatial-average vorticity. Under increased AO, the cyclonic mode complex also includes increased export of sea ice and near-surface freshwater, a changed path of Eurasian runoff, a freshened Beaufort Sea, and weakened cold halocline layer that insulates sea ice from Atlantic water heat, an impact compounded by increased Atlantic Water inflow and cyclonic circulation at depth. The cyclonic mode’s connection with the AO is important because the AO is a major global scale climate index predicted to increase with global warming. Given the present bias in concentration of in situ measurements in the Beaufort Gyre and Transpolar Drift, a coordinated effort should be made to better observe the cyclonic mode.

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11

Kenigson, Jessica S. y M. L. Timmermans. "Arctic Cyclone Activity and the Beaufort High". Journal of Climate 34, n.º 10 (mayo de 2021): 4119–27. http://dx.doi.org/10.1175/jcli-d-20-0771.1.

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AbstractThe Beaufort high (BH) and its accompanying anticyclonic winds drive the Arctic Ocean’s Beaufort Gyre, the major freshwater reservoir of the Arctic Ocean. The Beaufort Gyre circulation and its capacity to accumulate or release freshwater rely on the BH intensity. The migration of Nordic seas cyclones into the Arctic has been hypothesized to moderate the strength of the BH. We explore this hypothesis by analyzing reanalysis sea level pressure fields to characterize the BH and identify and track cyclones north of 60°N during 1948–2019. A cluster analysis of Nordic seas cyclone trajectories reveals a western pathway (through the Arctic interior) associated with a relatively weak BH and an eastern pathway (along the Arctic periphery) associated with a relatively strong BH. Furthermore, we construct cyclone activity indices (CAIs) in the Arctic and Nordic seas that take into account multiple cyclone parameters (number, strength, and duration). There are significant correlations between the BH and the CAIs in the Arctic and Nordic seas during 1948–2019, with anomalously strong cyclone activity related to an anomalously weak BH, and vice versa. We show how the Arctic and Nordic seas CAIs experienced a regime shift toward increased cyclone activity between the first four decades analyzed (1948–88) and the most recent three decades (1989–2019). Over the same two time periods, the BH exhibits a weakening. Increased cyclone activity and an accompanying weakening of the BH may be consistent with expectations in a warming Arctic and have implications for Beaufort Gyre dynamics and freshwater.

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12

McPhee, Miles G. "Intensification of Geostrophic Currents in the Canada Basin, Arctic Ocean". Journal of Climate 26, n.º 10 (8 de mayo de 2013): 3130–38. http://dx.doi.org/10.1175/jcli-d-12-00289.1.

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Abstract Continuous sampling of upper-ocean hydrographic data in the Canada Basin from various sources spanning from 2003 through 2011 provides an unprecedented opportunity to observe changes occurring in a major feature of the Arctic Ocean. In a 112-km-radius circle situated near the center of the traditional Beaufort Gyre, geopotential height referenced to 400 dbar increased by about 0.3 gpm from 2003 to 2011, and by the end of the period had increased by about 65% from the climatological value. Near the edges of the domain considered, the anomalies in dynamic height are much smaller, indicating steeper gradients. A rough dynamic topography constructed from profiles collected between 2008 and 2011 shows the center of the gyre to have shifted south by about 2° in latitude, along the 150°W meridian. Geostrophic currents are much stronger on the periphery of the gyre, reaching amplitudes 5–6 times higher than climatological values at grid points just offshore from the Beaufort and Chukchi shelf slopes. Estimates of residual buoy drift velocity after removing the expected wind-driven component are consistent with surface geostrophic currents calculated from hydrographic data. A three-decade time series of integrated ocean surface stress curl during late summer near the center of the Beaufort Gyre shows a large increase in downward Ekman pumping on decadal scales, emphasizing the importance of atmospheric forcing in the recent accumulation of freshwater in the Canada Basin. Geostrophic current intensification appears to have played a significant role in the recent disappearance of old ice in the Canada Basin.

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13

Duda, Timothy F., Ying-Tsong Lin, Weifeng G. Zhang, John A. Colosi y Mohsen Badiey. "Arctic Beaufort Gyre duct transmission measurements and simulations". Journal of the Acoustical Society of America 144, n.º 3 (septiembre de 2018): 1666. http://dx.doi.org/10.1121/1.5067426.

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14

Steele, M., W. Ermold, S. Häkkinen, D. Holland, G. Holloway, M. Karcher, F. Kauker, W. Maslowski, N. Steiner y J. Zhang. "Adrift in the Beaufort Gyre: A model intercomparison". Geophysical Research Letters 28, n.º 15 (1 de agosto de 2001): 2935–38. http://dx.doi.org/10.1029/2001gl012845.

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15

Proshutinsky, A. Yu, J. M. Toole, R. A. Krishfield, D. M. Anderson, C. J. Ashjian, A. B. Baggeroer, L. E. Freitag, R. S. Pickart y K. von der Heydt. "90 years of Arctic Ocean Exploration at the Woods Hole Oceanographic Institution". Journal of Oceanological Research 48, n.º 3 (30 de octubre de 2020): 164–98. http://dx.doi.org/10.29006/1564-2291.jor-2020.48(3).10.

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In 2020, the Woods Hole Oceanographic Institution (WHOI) celebrates 90 years of research, education, and exploration of the World Ocean. Since inception this has included Arctic studies. In fact, WHOI’s first technical report is on the oceanographic data obtained during the submarine “Nautilus” polar expedition in 1931. In 1951 and 1952, WHOI scientists supervised the collection of hydrographic data during the U.S. Navy SkiJump I & II expeditions utilizing ski-equipped aircraft landings in the Beaufort Sea, and inferred the Beaufort Gyre circulation cell and existence of a mid-Arctic ridge. Later classified studies, particularly concerning under-ice acoustics, were conducted by WHOI personnel from Navy and Air Force ice camps. With the advent of simple satellite communications and positioning, WHOI oceanographers began to deploy buoys on sea ice to obtain surface atmosphere, ice, and upper ocean time series data in the central Arctic beginning in 1987. Observations from these first systems were limited technologically to discrete depths and constrained by power considerations, satellite throughput, as well as high costs. As technologies improved, WHOI developed the drifting Ice-Tethered Profiler (ITP) to obtain vertically continuous upper ocean data several times per day in the ice-covered basins and telemeter the data back in near real time to the lab. Since the 1980s, WHOI scientists have also been involved in geological, biological, ecological and geochemical studies of Arctic waters, typically from expeditions utilizing icebreaking vessels, or air supported drifting platforms. Since the 2000s, WHOI has maintained oceanographic moorings on the Beaufort Shelf and in the deep Canada Basin, the latter an element of the Beaufort Gyre Observing System (BGOS). BGOS maintains oceanographic moorings via icebreaker, and conducts annual hydrographic and geochemical surveys each summer to document the Beaufort Gyre freshwater reservoir that has changed significantly since earlier investigations from the 1950s–1980s. With the experience and results demonstrated over the past decades for furthering Arctic research, WHOI scientists are well positioned to continue to explore and study the polar oceans in the decades ahead

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16

Zhao, Bowen y Mary-Louise Timmermans. "Topographic Rossby Waves in the Arctic Ocean's Beaufort Gyre". Journal of Geophysical Research: Oceans 123, n.º 9 (septiembre de 2018): 6521–30. http://dx.doi.org/10.1029/2018jc014233.

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17

Reimnitz, Erk, P. W. Barnes y W. S. Weber. "Particulate matter in pack ice of the Beaufort Gyre". Journal of Glaciology 39, n.º 131 (1993): 186–98. http://dx.doi.org/10.1017/s0022143000015823.

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Abstract Ice observations and sediment samples were collected in the Beaufort Gyre in 1988. Fine sediment occurred in very small patches of turbid ice, as thin spotty surface layers, in mud pellets or in old snowdrifts. The latter were widespread south of 74°N, containing an estimated 22 tonnes of silt and clay km−2. Average particle concentration in sea ice (40mg l−1) was much higher than in sea water (0.8 mg l−1) or in new snow, but the sediment load was significantly smaller and of finer texture compared to that observed in a shelfal source area after a major entrainment event. About 30% of the sediment consisted of small pellets. Mud in pellets has similar texture, clay minerals and organic/inorganic carbon content as dispersed mud. Particle sizes <16μm dominate, sand is less than 1%, compared to as much as 8% in four samples obtained in 1971 and 1972. Organic carbon content is about 2%, illite dominates clay minerals (~50%), and diatoms suggest a shelf sediment source. From the prevalence of wind-reworked surficial deposits, the spotty occurrence of only small patches of turbid ice in old clean ice, and the virtual lack of sand-size material, we assume the sediment had drifted at least 2 years since entrainment and was distant from its source. Assuming one-third of the load is released each year, the estimated deposition rate would equal the measured Holocene rate (~2cm 1000year−1). Therefore, modern sea-ice rafting represents a substantial fraction of the total Arctic Ocean sediment budget.

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Reimnitz, Erk, P. W. Barnes y W. S. Weber. "Particulate matter in pack ice of the Beaufort Gyre". Journal of Glaciology 39, n.º 131 (1993): 186–98. http://dx.doi.org/10.3189/s0022143000015823.

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AbstractIce observations and sediment samples were collected in the Beaufort Gyre in 1988. Fine sediment occurred in very small patches of turbid ice, as thin spotty surface layers, in mud pellets or in old snowdrifts. The latter were widespread south of 74°N, containing an estimated 22 tonnes of silt and clay km−2. Average particle concentration in sea ice (40mg l−1) was much higher than in sea water (0.8 mg l−1) or in new snow, but the sediment load was significantly smaller and of finer texture compared to that observed in a shelfal source area after a major entrainment event. About 30% of the sediment consisted of small pellets. Mud in pellets has similar texture, clay minerals and organic/inorganic carbon content as dispersed mud. Particle sizes <16μm dominate, sand is less than 1%, compared to as much as 8% in four samples obtained in 1971 and 1972. Organic carbon content is about 2%, illite dominates clay minerals (~50%), and diatoms suggest a shelf sediment source. From the prevalence of wind-reworked surficial deposits, the spotty occurrence of only small patches of turbid ice in old clean ice, and the virtual lack of sand-size material, we assume the sediment had drifted at least 2 years since entrainment and was distant from its source. Assuming one-third of the load is released each year, the estimated deposition rate would equal the measured Holocene rate (~2cm 1000year−1). Therefore, modern sea-ice rafting represents a substantial fraction of the total Arctic Ocean sediment budget.

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19

Warn-Varnas, Alex, Richard Allard y Steve Piacsek. "Synoptic and seasonal variations of the ice-ocean circulation in the Arctic: a numerical study". Annals of Glaciology 15 (1991): 54–62. http://dx.doi.org/10.3189/1991aog15-1-54-62.

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The circulations of the Arctic ice cover and ocean are investigated using a coupled ice-ocean model. The coupling is strong and two-way for synoptic time scales, but is limited on seasonal time scales: the geostrophic ocean currents are not changed by the computed heat and salt fluxes. The ice-drift motion, Ekman transports and the wind-driven part of the barotropic circulation are examined for the months of February and August 1986, representing different atmospheric forcing, ice-thickness and ice-strength regimes. Initial examination of the results revealed no significant seasonal dependence of ice-drift response on the synoptic time scale, other than larger velocities with larger wind stresses. Daily maximum ice-drift velocities range from 20-40 cm s−1 in February, and 15-30 cm s−1 in August. The corresponding mean monthly maximum drifts were 11 and 9 cm, respectively. The drag associated with the geostrophic currents plays a much bigger role in the summer because of the lighter atmospheric stresses. The well-known reversal of the normally clockwise Beaufort Gyre to a cyclonic system in August takes place in a few days and lasts well into September. In February, the Beaufort Gyre varies between a large, clockwise system covering all the Canadian Basin to a small, tight gyre centered over the southern Beaufort Sea, without any hint of reversal or disappearance. Large areas of strong divergence were found in the Ekman transport patterns, as well as the ice-divergence fields, indicating areas where ice thinning, openings and new ice formation might occur. In August this occurred in the Chukchi Sea, and in February just north of Novaya Zemlya.

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Warn-Varnas, Alex, Richard Allard y Steve Piacsek. "Synoptic and seasonal variations of the ice-ocean circulation in the Arctic: a numerical study". Annals of Glaciology 15 (1991): 54–62. http://dx.doi.org/10.1017/s026030550000954x.

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The circulations of the Arctic ice cover and ocean are investigated using a coupled ice-ocean model. The coupling is strong and two-way for synoptic time scales, but is limited on seasonal time scales: the geostrophic ocean currents are not changed by the computed heat and salt fluxes. The ice-drift motion, Ekman transports and the wind-driven part of the barotropic circulation are examined for the months of February and August 1986, representing different atmospheric forcing, ice-thickness and ice-strength regimes. Initial examination of the results revealed no significant seasonal dependence of ice-drift response on the synoptic time scale, other than larger velocities with larger wind stresses. Daily maximum ice-drift velocities range from 20-40 cm s−1 in February, and 15-30 cm s−1 in August. The corresponding mean monthly maximum drifts were 11 and 9 cm, respectively. The drag associated with the geostrophic currents plays a much bigger role in the summer because of the lighter atmospheric stresses. The well-known reversal of the normally clockwise Beaufort Gyre to a cyclonic system in August takes place in a few days and lasts well into September. In February, the Beaufort Gyre varies between a large, clockwise system covering all the Canadian Basin to a small, tight gyre centered over the southern Beaufort Sea, without any hint of reversal or disappearance. Large areas of strong divergence were found in the Ekman transport patterns, as well as the ice-divergence fields, indicating areas where ice thinning, openings and new ice formation might occur. In August this occurred in the Chukchi Sea, and in February just north of Novaya Zemlya.

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21

Manucharyan, Georgy E., Andrew F. Thompson y Michael A. Spall. "Eddy Memory Mode of Multidecadal Variability in Residual-Mean Ocean Circulations with Application to the Beaufort Gyre". Journal of Physical Oceanography 47, n.º 4 (abril de 2017): 855–66. http://dx.doi.org/10.1175/jpo-d-16-0194.1.

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AbstractMesoscale eddies shape the Beaufort Gyre response to Ekman pumping, but their transient dynamics are poorly understood. Climate models commonly use the Gent–McWilliams (GM) parameterization, taking the eddy streamfunction to be proportional to an isopycnal slope s and an eddy diffusivity K. This local-in-time parameterization leads to exponential equilibration of currents. Here, an idealized, eddy-resolving Beaufort Gyre model is used to demonstrate that carries a finite memory of past ocean states, violating a key GM assumption. As a consequence, an equilibrating gyre follows a spiral sink trajectory implying the existence of a damped mode of variability—the eddy memory (EM) mode. The EM mode manifests during the spinup as a 15% overshoot in isopycnal slope (2000 km3 freshwater content overshoot) and cannot be explained by the GM parameterization. An improved parameterization is developed, such that is proportional to an effective isopycnal slope , carrying a finite memory γ of past slopes. Introducing eddy memory explains the model results and brings to light an oscillation with a period ≈ 50 yr, where the eddy diffusion time scale TE ~ 10 yr and γ ≈ 6 yr are diagnosed from the eddy-resolving model. The EM mode increases the Ekman-driven gyre variance by γ/TE ≈ 50% ± 15%, a fraction that stays relatively constant despite both time scales decreasing with increased mean forcing. This study suggests that the EM mode is a general property of rotating turbulent flows and highlights the need for better observational constraints on transient eddy field characteristics.

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22

Spall, Michael. "Potential Vorticity Dynamics of the Arctic Halocline". Journal of Physical Oceanography 50, n.º 9 (1 de septiembre de 2020): 2491–506. http://dx.doi.org/10.1175/jpo-d-20-0056.1.

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AbstractAn idealized two-layer shallow water model is applied to the study of the dynamics of the Arctic Ocean halocline. The model is forced by a surface stress distribution reflective of the observed wind stress pattern and ice motion and by an inflow representing the flow of Pacific Water through Bering Strait. The model reproduces the main elements of the halocline circulation: an anticyclonic Beaufort Gyre in the western basin (representing the Canada Basin), a cyclonic circulation in the eastern basin (representing the Eurasian Basin), and a Transpolar Drift between the two gyres directed from the upwind side of the basin to the downwind side of the basin. Analysis of the potential vorticity budget shows a basin-averaged balance primarily between potential vorticity input at the surface and dissipation at the lateral boundaries. However, advection is a leading-order term not only within the anticyclonic and cyclonic gyres but also between the gyres. This means that the eastern and western basins are dynamically connected through the advection of potential vorticity. Both eddy and mean fluxes play a role in connecting the regions of potential vorticity input at the surface with the opposite gyre and with the viscous boundary layers. These conclusions are based on a series of model runs in which forcing, topography, straits, and the Coriolis parameter were varied.

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23

Lu, Jinling, Ling Du y Shuhao Tao. "Long-term eddy modulation affects the meridional asymmetry of the halocline in the Beaufort Gyre". Ocean Science 19, n.º 6 (13 de diciembre de 2023): 1773–89. http://dx.doi.org/10.5194/os-19-1773-2023.

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Abstract. Against the background of wind-forcing change along with Arctic sea ice retreat, the mesoscale processes undergoing distinct variation in the Beaufort Gyre (BG) region are increasingly important to oceanic transport and energy cascades, and these changes subsequently put oceanic stratification into a new state. Here, the varying number and strength of eddies in the central Canada Basin (CB) and Chukchi–Beaufort continental slope are obtained based on mooring observations (2003–2018), altimetry measurements (1993–2019), and reanalysis data (1980–2020). In this paper, the variability in the BG halocline, representing the adjustment of stratification in the upper layer, is shown in order to analyse how variability occurs under changing mesoscale processes. We find that over almost the last 2 decades the halocline depth has deepened by ∼ 40 m in the south of the central gyre, while that in the north has deepened by ∼ 70 m according to multiple datasets. Surrounding the central gyre, the asymmetry of the halocline, with much steeper and deeper isopycnals over the southern continental slope, reduced after 2014. In the meantime, eddy activities in the upper layer from the southern margin of the BG to the abyssal plain have been enhanced. Moreover, the convergence of the eddy lateral flux has increased as the halocline structures on either side, which is at least 120 km from the central gyre, have reached a nearly identical and stable regime. It has been clarified that long-term dynamic eddy modulation through eddy fluxes, facilitating the freshwater redistribution, affects the meridional asymmetry of the BG halocline. Our results provide a better understanding of the eddy modulation processes and their influence on the halocline structure.

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24

Zhao, Mengnan, Mary‐Louise Timmermans, Richard Krishfield y Georgy Manucharyan. "Partitioning of Kinetic Energy in the Arctic Ocean's Beaufort Gyre". Journal of Geophysical Research: Oceans 123, n.º 7 (julio de 2018): 4806–19. http://dx.doi.org/10.1029/2018jc014037.

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25

Kelly, S. J., A. Proshutinsky, E. K. Popova, Y. K. Aksenov y A. Yool. "On the Origin of Water Masses in the Beaufort Gyre". Journal of Geophysical Research: Oceans 124, n.º 7 (julio de 2019): 4696–709. http://dx.doi.org/10.1029/2019jc015022.

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26

Proshutinsky, A., R. Krishfield, J. M. Toole, M. ‐L Timmermans, W. Williams, S. Zimmermann, M. Yamamoto‐Kawai et al. "Analysis of the Beaufort Gyre Freshwater Content in 2003–2018". Journal of Geophysical Research: Oceans 124, n.º 12 (diciembre de 2019): 9658–89. http://dx.doi.org/10.1029/2019jc015281.

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27

Wendel, JoAnna. "Beaufort Gyre sea ice thins in recent decades, impacts climate". Eos, Transactions American Geophysical Union 95, n.º 22 (3 de junio de 2014): 192. http://dx.doi.org/10.1002/2014eo220011.

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28

Zhang, Jinlun, Michael Steele, Kay Runciman, Sarah Dewey, James Morison, Craig Lee, Luc Rainville et al. "The Beaufort Gyre intensification and stabilization: A model-observation synthesis". Journal of Geophysical Research: Oceans 121, n.º 11 (noviembre de 2016): 7933–52. http://dx.doi.org/10.1002/2016jc012196.

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29

Ma, Barry, Michael Steele y Craig M. Lee. "Ekman circulation in the Arctic Ocean: Beyond the Beaufort Gyre". Journal of Geophysical Research: Oceans 122, n.º 4 (abril de 2017): 3358–74. http://dx.doi.org/10.1002/2016jc012624.

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30

Dosser, Hayley V. y Mary-Louise Timmermans. "Inferring Circulation and Lateral Eddy Fluxes in the Arctic Ocean’s Deep Canada Basin Using an Inverse Method". Journal of Physical Oceanography 48, n.º 2 (febrero de 2018): 245–60. http://dx.doi.org/10.1175/jpo-d-17-0190.1.

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AbstractThe deep waters in the Canada Basin display a complex temperature and salinity structure, the evolution of which is poorly understood. The fundamental physical processes driving changes in these deep water masses are investigated using an inverse method based on tracer conservation combined with empirical orthogonal function analysis of repeat hydrographic measurements between 2003 and 2015. Changes in tracer fields in the deep Canada Basin are found to be dominated by along-isopycnal diffusion of water properties from the margins into the central basin, with advection by the large-scale Beaufort Gyre circulation as well as localized, vertical mixing playing important secondary roles. In the Barents Sea branch of the Atlantic Water layer, centered around 1200-m depth, diffusion is shown to be nearly twice as important as advection to lateral transport. Along-isopycnal diffusivity is estimated to be ~300–600 m2 s−1. Large-scale circulation patterns and lateral advective velocities associated with the anticyclonic Beaufort Gyre are inferred, with an average speed of 0.6 cm s−1. Below about 1500 m, along-isopycnal diffusivity is estimated to be ~200–400 m2 s−1.

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31

Forbes, J. R., R. W. Macdonald, E. C. Carmack, K. Iseki y M. C. O'Brien. "Zooplankton Retained in Sequential Sediment Traps along the Beaufort Sea Shelf Break during Winter". Canadian Journal of Fisheries and Aquatic Sciences 49, n.º 4 (1 de abril de 1992): 663–70. http://dx.doi.org/10.1139/f92-075.

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Zooplankton retained in four sediment traps deployed along the shelf break of the eastern Beaufort Sea, from September 1987 to March 1988, were used to investigate temporal and regional variations of the zooplankton community during winter. Despite trap selectivity, the species composition indicated that both the shelf community and Atlantic water community of the deep Arctic Ocean are excluded from the shelf break at this time of year. There was no evidence of off-shelf transport during the study period. Taxa collected, predominantly pteropods (Spiratella helicina) and calanoid copepods, were typical of the community in the upper 200 m of the central Arctic Ocean. The abundance of pteropods was strongly associated with ice cover. The easternmost trap, located at the entrance to Amundsen Gulf, had a distribution of animals distinct from those in the other traps. It lay outside the influence of the Beaufort Gyre and Beaufort Undercurrent, which apparently affected the other locations.

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32

Hall, Sarah B., Bulusu Subrahmanyam y James H. Morison. "Intercomparison of Salinity Products in the Beaufort Gyre and Arctic Ocean". Remote Sensing 14, n.º 1 (24 de diciembre de 2021): 71. http://dx.doi.org/10.3390/rs14010071.

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Salinity is the primary determinant of the Arctic Ocean’s density structure. Freshwater accumulation and distribution in the Arctic Ocean have varied significantly in recent decades and certainly in the Beaufort Gyre (BG). In this study, we analyze salinity variations in the BG region between 2012 and 2017. We use in situ salinity observations from the Seasonal Ice Zone Reconnaissance Surveys (SIZRS), CTD casts from the Beaufort Gyre Exploration Project (BGP), and the EN4 data to validate and compare with satellite observations from Soil Moisture Active Passive (SMAP), Soil Moisture and Ocean Salinity (SMOS), and Aquarius Optimally Interpolated Sea Surface Salinity (OISSS), and Arctic Ocean models: ECCO, MIZMAS, HYCOM, ORAS5, and GLORYS12. Overall, satellite observations are restricted to ice-free regions in the BG area, and models tend to overestimate sea surface salinity (SSS). Freshwater Content (FWC), an important component of the BG, is computed for EN4 and most models. ORAS5 provides the strongest positive SSS correlation coefficient (0.612) and lowest bias to in situ observations compared to the other products. ORAS5 subsurface salinity and FWC compare well with the EN4 data. Discrepancies between models and SIZRS data are highest in GLORYS12 and ECCO. These comparisons identify dissimilarities between salinity products and extend challenges to observations applicable to other areas of the Arctic Ocean.

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33

Long, Z., W. Perrie, C. L. Tang, E. Dunlap y J. Wang. "Simulated Interannual Variations of Freshwater Content and Sea Surface Height in the Beaufort Sea*". Journal of Climate 25, n.º 4 (8 de febrero de 2012): 1079–95. http://dx.doi.org/10.1175/2011jcli4121.1.

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Abstract The authors investigate the interannual variations of freshwater content (FWC) and sea surface height (SSH) in the Beaufort Sea, particularly their increases during 2004–09, using a coupled ice–ocean model (CIOM), adapted for the Arctic Ocean to simulate the interannual variations. The CIOM simulation exhibits a (relative) salinity minimum in the Beaufort Sea and a warm Atlantic water layer in the Arctic Ocean, which is similar to the Polar Hydrographic Climatology (PHC), and captures the observed FWC maximum in the central Beaufort Sea, and the observed variation and rapid decline of total ice concentration, over the last 30 years. The model simulations of SSH and FWC suggest a significant increase in the central Beaufort Sea during 2004–09. The simulated SSH increase is about 8 cm, while the FWC increase is about 2.5 m, with most of these increases occurring in the center of the Beaufort gyre. The authors show that these increases are due to an increased surface wind stress curl during 2004–09, which increased the FWC in the Beaufort Sea by about 0.63 m yr−1 through Ekman pumping. Moreover, the increased surface wind is related to the interannual variation of the Arctic polar vortex at 500 hPa. During 2004–09, the polar vortex had significant weakness, which enhanced the Beaufort Sea high by affecting the frequency of synoptic weather systems in the region. In addition to the impacts of the polar vortex, enhanced melting of sea ice also contributes to the FWC increase by about 0.3 m yr−1 during 2004–09.

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34

Ivanov, N. E., D. M. Demchev y A. V. Nesterov. "Application of A.M. Obukhov’s theory of correlation of vectors for scientific research and engineering calculations of ice drift in the Arctic Ocean." IOP Conference Series: Earth and Environmental Science 1040, n.º 1 (1 de junio de 2022): 012024. http://dx.doi.org/10.1088/1755-1315/1040/1/012024.

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Abstract The theory of vectors correlation of Obukhov was used to describe an ice drift in the Arctic Ocean. The main features are defined by an area. The tracks tortuosity in Beaufort Gyre and Transarctic current varies threefold: 1.5 and 4.5. Year to year and seasonal variations indicate the position of the Beaufort Gyre and the speed of the Transarctic drift. The average speed does not exceed 10 cm/s. The drift increases in summer, and in winter it intensifies in Fram Strait. In Fram Strait the velocity month–over–month increases from June to December–March from 2.5 to 6.5 cm/s. Overall correlation drift and wind is 0.95 and 0.85 for ice fields and icebergs. The non-wind drift reproduces the cyclonic circulation between Frantz Josef Land and Novaya Zemlya. The wind drift specifies the coefficients and angles of drift evasion from the wind. The coefficient for total drift is 0.14–0.18, fore wind drift 0.10–0.15, and the angles are 15–30° and 10–15° in the Barents Sea. In the Fram Strait the drift and wind directions are stable, the trend considers the modulus and direction. The drift trend has the direction towards the south. It decreases to 5 % of variance in June and increases to 15% from December to March.

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35

Macdonald, R. W., E. C. Carmack, F. A. McLaughlin, K. K. Falkner y J. H. Swift. "Connections among ice, runoff and atmospheric forcing in the Beaufort Gyre". Geophysical Research Letters 26, n.º 15 (1 de agosto de 1999): 2223–26. http://dx.doi.org/10.1029/1999gl900508.

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36

Zhang, S., Y. Zuo, F. Xiao, L. Yuan, T. Geng y Y. Xuan. "PRELIMINARY RESULTS OF SEA ICE FREEBOARD MEASUREMENTS OF BEAUFORT SEA FROM CRYOSAT-2 ALTIMETRY". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W13 (5 de junio de 2019): 1811–15. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w13-1811-2019.

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<p><strong>Abstract.</strong> Satellite altimetry has been used to observe the Arctic sea ice in long term and large scale, and the records show a continued decline for Arctic sea ice thickness over decades. In this study, the sea ice freeboard in Beaufort Sea of Arctic have been estimated using CryoSat-2 data, and validated with Upward Looking Sonar (ULS) data of Beaufort Gyre Exploration Project (BGEP). The results show an obvious seasonal variation of the Beaufort Sea with a high reliability estimation of the sea ice freeboard. The average height of the sea ice freeboard increase from January to March and achieve the maximum value 0.38&thinsp;m in March. The sea ice melts after March and the average height of the sea ice freeboard reduces to the minimum 0.12&thinsp;m in August. In the next few months the sea water begins to freeze and the average height of the sea ice freeboard will increase to the maximum value.</p>

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37

Colosi, John A., Heriberto J. Vazquez, Bruce Cornuelle, Peter F. Worcester y Matthew A. Dzieciuch. "Estimation of surface layer and Pacific summer water properties from acoustic transmissions in the Beaufort duct using a tomographic array during 2016–2017". Journal of the Acoustical Society of America 154, n.º 4_supplement (1 de octubre de 2023): A133. http://dx.doi.org/10.1121/10.0023030.

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The 2016–2017 Canada Basin Acoustic Propagation Experiment (CANAPE) was conducted to assess the effects of the changing Beaufort Gyre on low-frequency underwater acoustic propagation and ambient sound. A 150-km radius ocean acoustic tomography array was deployed with six transceivers and a distributed vertical line array (DVLA) measuring the impulse responses every four hours with broadband signals centered from 172.5 to 275 Hz. The nominal transceiver source depth was 175-m, placing them near the Beaufort duct axis, and the 60 hydrophone DVLA spanned 50 to 600 m. The Beaufort duct (approximately 90-m to 240-m depth) and the surface layer (approximately 0 to 90-m depth) form a coupled double-duct system. Observed arrivals in this system show reverse dispersion with the lowest Beaufort duct modes arriving first and higher double duct modes making up a transmission finale. In this talk, we investigate the oceanographic information content contained in the first and last arrivals which are the easiest to detect and track. The first arrival shows fluctuations from eddies, tides/inertial oscillations, and small seasonal heating/cooling. The last arrival shows a strong seasonal heating/cooling signal but is un-trackable during periods of significant ice cover due to enhanced transmission loss.

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38

Preller, Ruth H. y Pamela G. Posey. "A numerical model simulation of a summer reversal of the Beaufort Gyre". Geophysical Research Letters 16, n.º 1 (enero de 1989): 69–72. http://dx.doi.org/10.1029/gl016i001p00069.

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39

Regan, Heather C., Camille Lique y Thomas W. K. Armitage. "The Beaufort Gyre Extent, Shape, and Location Between 2003 and 2014 From Satellite Observations". Journal of Geophysical Research: Oceans 124, n.º 2 (febrero de 2019): 844–62. http://dx.doi.org/10.1029/2018jc014379.

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40

Dainard, Paul G., Céline Guéguen, Natasha McDonald y William J. Williams. "Photobleaching of fluorescent dissolved organic matter in Beaufort Sea and North Atlantic Subtropical Gyre". Marine Chemistry 177 (diciembre de 2015): 630–37. http://dx.doi.org/10.1016/j.marchem.2015.10.004.

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41

DeGrandpre, Michael D., Chun‐Ze Lai, Mary‐Louise Timmermans, Richard A. Krishfield, Andrey Proshutinsky y Daniel Torres. "Inorganic Carbon andpCO2Variability During Ice Formation in the Beaufort Gyre of the Canada Basin". Journal of Geophysical Research: Oceans 124, n.º 6 (junio de 2019): 4017–28. http://dx.doi.org/10.1029/2019jc015109.

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42

Duda, Timothy F. "Prospects for acoustic remote sensing and acoustic system performance in the Beaufort Gyre region". Journal of the Acoustical Society of America 152, n.º 4 (octubre de 2022): A111. http://dx.doi.org/10.1121/10.0015716.

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In the Beaufort Gyre region north of Alaska, the vertical interleaving of the near-surface temperature maximum, the warm Pacific Summer Water (PSW), the cool Pacific Winter Water, and the Atlantic layer make for unusual acoustic conditions. The dynamics of these upper ocean layers cause typical complex and turbulent-like oceanic flow that causes geographically variable heat content and acoustics. A sound duct in the PWW, below the PSW and above the Atlantic Layer, filling ∼75 to 225 m depth, is prominent but not universal. Erosion of the PSW warm layer by either vertical or horizontal mixing processes often breaks the duct, with an additional seasonal cycle of ducting effectiveness, and allows sound to escape to interact with the scattering and attenuating surface. The duct enables communication and navigation signaling, but with that interruption caveat. It also allows passive sensing, best for sound that enters the duct and moves through it. A challenge is to utilize sound that exists outside the duct. This includes sounds emitted outside the duct by mammals, fracturing ice, or anything else. This sound will either cycle through the duct at steep angle, or stay above the duct and repeatedly reflect from the top boundary. The combination of unducted sound being subject to strong attenuation by ice or wave interaction (the typical high-latitude situation) and high variability of the duct effectiveness, imposes limitations on the usefulness of the otherwise convenient duct.

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43

Manucharyan, Georgy E. y Michael A. Spall. "Wind‐driven freshwater buildup and release in the Beaufort Gyre constrained by mesoscale eddies". Geophysical Research Letters 43, n.º 1 (6 de enero de 2016): 273–82. http://dx.doi.org/10.1002/2015gl065957.

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44

Zhong, Wenli, Jinping Zhao, Jiuxin Shi y Yong Cao. "The Beaufort Gyre variation and its impacts on the Canada Basin in 2003–2012". Acta Oceanologica Sinica 34, n.º 7 (julio de 2015): 19–31. http://dx.doi.org/10.1007/s13131-015-0657-0.

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45

Solomon, Amy, Céline Heuzé, Benjamin Rabe, Sheldon Bacon, Laurent Bertino, Patrick Heimbach, Jun Inoue et al. "Freshwater in the Arctic Ocean 2010–2019". Ocean Science 17, n.º 4 (17 de agosto de 2021): 1081–102. http://dx.doi.org/10.5194/os-17-1081-2021.

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Abstract. The Arctic climate system is rapidly transitioning into a new regime with a reduction in the extent of sea ice, enhanced mixing in the ocean and atmosphere, and thus enhanced coupling within the ocean–ice–atmosphere system; these physical changes are leading to ecosystem changes in the Arctic Ocean. In this review paper, we assess one of the critically important aspects of this new regime, the variability of Arctic freshwater, which plays a fundamental role in the Arctic climate system by impacting ocean stratification and sea ice formation or melt. Liquid and solid freshwater exports also affect the global climate system, notably by impacting the global ocean overturning circulation. We assess how freshwater budgets have changed relative to the 2000–2010 period. We include discussions of processes such as poleward atmospheric moisture transport, runoff from the Greenland Ice Sheet and Arctic glaciers, the role of snow on sea ice, and vertical redistribution. Notably, sea ice cover has become more seasonal and more mobile; the mass loss of the Greenland Ice Sheet increased in the 2010s (particularly in the western, northern, and southern regions) and imported warm, salty Atlantic waters have shoaled. During 2000–2010, the Arctic Oscillation and moisture transport into the Arctic are in-phase and have a positive trend. This cyclonic atmospheric circulation pattern forces reduced freshwater content on the Atlantic–Eurasian side of the Arctic Ocean and freshwater gains in the Beaufort Gyre. We show that the trend in Arctic freshwater content in the 2010s has stabilized relative to the 2000s, potentially due to an increased compensation between a freshening of the Beaufort Gyre and a reduction in freshwater in the rest of the Arctic Ocean. However, large inter-model spread across the ocean reanalyses and uncertainty in the observations used in this study prevent a definitive conclusion about the degree of this compensation.

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46

Rabe, B., P. Dodd, E. Hansen, E. Falck, U. Schauer, A. Mackensen, A. Beszczynska-Möller, G. Kattner, E. J. Rohling y K. Cox. "Export of Arctic freshwater components through the Fram Strait 1998–2010". Ocean Science Discussions 9, n.º 4 (14 de agosto de 2012): 2749–92. http://dx.doi.org/10.5194/osd-9-2749-2012.

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Abstract. The East Greenland Current in the Western Fram Strait is an important pathway for liquid freshwater export from the Arctic Ocean to the Nordic Seas and the North Atlantic subpolar gyre. We analysed five hydrographic surveys and data from moored current meters around 79° N in the Western Fram Strait between 1998 and 2010. To estimate the composition of southward liquid freshwater transports, inventories of liquid freshwater and components from Dodd et al. (2012) were combined with transport estimates from an inverse model between 10.6° W and 4° E. The southward liquid freshwater transports through the section averaged to 92 mSv (2900 km3 yr−1), relative to a salinity of 34.9. The transports consisted of 123 mSv water from rivers and precipitation (meteoric water), 28 mSv freshwater from the Pacific and 60 mSv freshwater deficit due to brine from ice formation. Variability in liquid freshwater and component transports appear to have been partly due to advection of these water masses to the Fram Strait and partly due to variations in the local volume transport; an exception are Pacific Water transports, which showed little co-variability with volume transports. An increase in Pacific Water transports from 2005 to 2010 suggests a release of Pacific Water from the Beaufort Gyre, in line with an observed expansion of Pacific Water towards the Eurasian Basin. The co-variability of meteoric water and brine from ice formation suggests joint processes in the main sea ice formation regions on the Arctic Ocean shelves. In addition, enhanced levels of sea ice melt observed in 2009 likely led to reduced transports of brine from ice formation. At least part of this additional ice melt appears to have been advected from the Beaufort Gyre and from north of the Bering Strait towards the Fram Strait. The observed changes in liquid freshwater component transports are much larger than known trends in the Arctic liquid freshwater inflow from rivers and the Pacific. Instead, recent observations of an increased storage of liquid freshwater in the Arctic Ocean suggest a decreased export of liquid freshwater. This raises the question how fast the accumulated liquid freshwater will be exported from the Arctic Ocean to the deep water formation regions in the North Atlantic and if an increased export will occur through the Fram Strait.

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47

Giles, Katharine A., Seymour W. Laxon, Andy L. Ridout, Duncan J. Wingham y Sheldon Bacon. "Western Arctic Ocean freshwater storage increased by wind-driven spin-up of the Beaufort Gyre". Nature Geoscience 5, n.º 3 (22 de enero de 2012): 194–97. http://dx.doi.org/10.1038/ngeo1379.

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48

Proshutinsky, A., R. H. Bourke y F. A. McLaughlin. "The role of the Beaufort Gyre in Arctic climate variability: Seasonal to decadal climate scales". Geophysical Research Letters 29, n.º 23 (diciembre de 2002): 15–1. http://dx.doi.org/10.1029/2002gl015847.

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49

Worcester, Peter F., Matthew A. Dzieciuch, Heriberto J. Vazquez, John A. Colosi y Richard A. Krishfield. "Acoustic transmission loss observed on a tomographic array in the Beaufort Gyre during 2016–2017". Journal of the Acoustical Society of America 154, n.º 4_supplement (1 de octubre de 2023): A83. http://dx.doi.org/10.1121/10.0022877.

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The Arctic Ocean is undergoing dramatic changes. The 2016–2017 Canada Basin Acoustic Propagation Experiment (CANAPE) was conducted to assess the effects of the changes in the sea ice and ocean structure in the Beaufort Gyre on low-frequency underwater acoustic propagation and ambient sound. An ocean acoustic tomography array with a radius of 150 km that consisted of six transceivers and a long vertical receiving array measured the impulse responses of the ocean every four hours using broadband signals with center frequencies that ranged from 172.5 to 275 Hz. Ice-profiling sonar data showed a gradual increase in ice draft over the winter with daily median ice drafts reaching maxima of about 1.5 m, suggesting that the ice was first-year ice. The transmission loss of early, resolved ray arrivals from steep ray paths with lower turning depths below 500 m was lowest when open water was present and increased as the ice draft increased. The transmission loss per surface reflection increased with center frequency and surface grazing angle. The values are greater than observed during the 1988–1989 Greenland Sea Tomography experiment, but the ice conditions likely differed significantly.

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50

Rella, S. F. y M. Uchida. "Sedimentary organic matter and carbonate variations in the Chukchi Borderland in association with ice sheet and ocean-atmosphere dynamics over the last 155 kyr". Biogeosciences 8, n.º 12 (6 de diciembre de 2011): 3545–53. http://dx.doi.org/10.5194/bg-8-3545-2011.

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Abstract. Knowledge on past variability of sedimentary organic carbon in the Arctic Ocean is important to assess natural carbon cycling and transport processes related to global climate changes. However, the late Pleistocene oceanographic history of the Arctic is still poorly understood. In the present study we show sedimentary records of total organic carbon (TOC), CaCO3, benthic foraminiferal δ18O and the coarse grain size fraction from a piston core recovered from the northern Northwind Ridge in the far western Arctic Ocean, a region potentially sensitively responding to past variability in surface current regimes and sedimentary processes such as coastal erosion. An age model based on oxygen stratigraphy, radiocarbon dating and lithological constraints suggests that the piston core records paleoenvironmental changes of the last 155 kyr. TOC shows orbital-scale increases and decreases that can be respectively correlated to the waxing and waning of large ice sheets dominating the Eurasian Arctic, suggesting advection of fine suspended matter derived from glacial erosion to the Northwind Ridge by eastward flowing intermediate water and/or surface water and sea ice during cold episodes of the last two glacial-interglacial cycles. At millennial scales, increases in TOC might correlate to a suite of Dansgaard-Oeschger Stadials between 120 and 45 ka before present (BP) indicating a possible response to abrupt northern hemispheric temperature changes. Between 70 and 45 ka BP, closures and openings of the Bering Strait could have additionally influenced TOC variability. CaCO3 content tends to anti-correlate with TOC on both orbital and millennial time scales, which we interpret in terms of enhanced sediment advection from the carbonate-rich Canadian Arctic via an extended Beaufort Gyre during warm periods of the last two glacial-interglacial cycles and increased organic carbon advection from the Siberian Arctic during cold periods when the Beaufort Gyre contracted. We propose that this pattern may be related to orbital- and millennial-scale variations of dominant atmospheric surface pressure systems expressed in mode shifts of the Arctic Oscillation.

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