Deepening of the Winter Mixed Layer in the Canada Basin, Arctic Ocean Over 2006–2017

Cole, Sylvia T.; Stadler, James

doi:10.1029/2019jc014940

Cited by 18 publications

(18 citation statements)

References 30 publications

(70 reference statements)

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“…Western Arctic mixed layers are highly seasonal, with summer ice melt creating a thin and very fresh mixed layer, with sharp stratification at its base separating it from halocline waters (Toole et al., 2010). Beginning in autumn and continuing through the winter, storms deepen the mixed layer, with typical maximum thickness in the spring of 40–50 m (Cole & Stadler, 2019). In the current study, we do not observe mixed layer depth, and thus cannot separate the influence of either mixed layer depth or the strength of stratification at the base of the mixed layer from changes in ice concentration and draft, which are also highly seasonal (Figure 6).…”

Section: Discussionmentioning

confidence: 99%

Decadal Observations of Internal Wave Energy, Shear, and Mixing in the Western Arctic Ocean

Fine

Cole

2022

JGR Oceans

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As Arctic sea ice declines, wind energy has increasing access to the upper ocean, with potential consequences for ocean mixing, stratification, and turbulent heat fluxes. Here, we investigate the relationships between internal wave energy, turbulent dissipation, and ice concentration and draft using mooring data collected in the Beaufort Sea during 2003–2018. We focus on the 50–300 m depth range, using velocity and CTD records to estimate near‐inertial shear and energy, a finescale parameterization to infer turbulent dissipation rates, and ice draft observations to characterize the ice cover. All quantities varied widely on monthly and interannual timescales. Seasonally, near‐inertial energy increased when ice concentration and ice draft were low, but shear and dissipation did not. We show that this apparent contradiction occurred due to the vertical scales of internal wave energy, with open water associated with larger vertical scales. These larger vertical scale motions are associated with less shear, and tend to result in less dissipation. This relationship led to a seasonality in the correlation between shear and energy. This correlation was largest in the spring beneath full ice cover and smallest in the summer and fall when the ice had deteriorated. When considering interannually averaged properties, the year‐to‐year variability and the short ice‐free season currently obscure any potential trend. Implications for the future seasonal and interannual evolution of the Arctic Ocean and sea ice cover are discussed.

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Section: Discussionmentioning

confidence: 99%

Decadal Observations of Internal Wave Energy, Shear, and Mixing in the Western Arctic Ocean

Fine

Cole

2022

JGR Oceans

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“…Depth profile analysis in this study highlights the variability at depths shallower than 55 m and between 55 and 207 m for deeper layer comparisons. Past research has commonly defined the mixed layer depth as the depth where the density increase above the mixed layer reaches 0.25 kg/m 3 , which is consistently deeper than 10 m in the BG and can reach 30 m in the winter [34,41,42]. In contrast, Jackson et al [43] emphasize that the alteration of the upper 100 m of the Canadian Basin has been influenced by heightened temperatures and freshwater levels where the mixed layer depth during winter months shoaled from 50 m prior to the 1970s to around 24 m more recently.…”

Section: Vertical Salinity Structurementioning

confidence: 99%

Intercomparison of Salinity Products in the Beaufort Gyre and Arctic Ocean

2021

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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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“…These papers shed light on the origins of various layer types associated with heat and salt transport, as well as the role of turbulence in limiting double‐diffusive heat fluxes. Cole and Stadler () investigate the surface ocean and report a deepening by 9 m (about 20%) of the winter mixed layer in the Beaufort Gyre region in 2013‐2017 relative to 2006‐2012 and discuss potential causes for this deepening. Chanona et al () analyze a large number of conductivity‐temperature‐pressure profiles to characterize internal wave‐driven turbulent dissipation rates; they find a weak seasonal cycle and an absence of interannual variability and trends in the rates of dissipation.…”

Section: Beaufort Gyre Phenomenon: Multicomponent System Mechanisms Amentioning

confidence: 99%

“…Cole and Stadler (2019) investigate the surface ocean and report a deepening by 9 m 10.1029/2019JC015400 (about 20%) of the winter mixed layer in the Beaufort Gyre region in 2013-2017 relative to 2006-2012 and discuss potential causes for this deepening.Chanona et al (…”

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confidence: 99%

Introduction to Special Collection on Arctic Ocean Modeling and Observational Synthesis (FAMOS) 2: Beaufort Gyre Phenomenon

2020

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One of the foci of the Forum for Artic Modeling and Observational Synthesis (FAMOS) project is improving Arctic regional ice‐ocean models and understanding of physical processes regulating variability of Arctic environmental conditions based on synthesis of observations and model results. The Beaufort Gyre, centered in the Canada Basin of the Arctic Ocean, is an ideal phenomenon and natural laboratory for application of FAMOS modeling capabilities to resolve numerous scientific questions related to the origin and variability of this climatologic freshwater reservoir and flywheel of the Arctic Ocean. The unprecedented volume of data collected in this region is nearly optimal to describe the state and changes in the Beaufort Gyre environmental system at synoptic, seasonal, and interannual time scales. The in situ and remote sensing data characterizing ocean hydrography, sea surface heights, ice drift, concentration and thickness, ocean circulation, and biogeochemistry have been used for model calibration and validation or assimilated for historic reconstructions and establishing initial conditions for numerical predictions. This special collection of studies contributes time series of the Beaufort Gyre data; new methodologies in observing, modeling, and analysis; interpretation of measurements and model output; and discussions and findings that shed light on the mechanisms regulating Beaufort Gyre dynamics as it transitions to a new state under different climate forcing.

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Deepening of the Winter Mixed Layer in the Canada Basin, Arctic Ocean Over 2006–2017

Cited by 18 publications

References 30 publications

Decadal Observations of Internal Wave Energy, Shear, and Mixing in the Western Arctic Ocean

Decadal Observations of Internal Wave Energy, Shear, and Mixing in the Western Arctic Ocean

Intercomparison of Salinity Products in the Beaufort Gyre and Arctic Ocean

Introduction to Special Collection on Arctic Ocean Modeling and Observational Synthesis (FAMOS) 2: Beaufort Gyre Phenomenon

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