Phased Response of the Subpolar Southern Ocean to Changes in Circumpolar Winds

Garabato, Alberto C. Naveira; Dotto, Tiago S.; Hooley, Jack; Bacon, Sheldon; Ridout, A.; Frajka‐Williams, Eleanor; Herráiz‐Borreguero, Laura; Holland, Paul R.; Heorton, Harry; Meredith, Michael P.

doi:10.1029/2019gl082850

Cited by 28 publications

(36 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This suggests that the variability in barotropic transport is indeed connected with remote forcing. In fact, Naveira Garabato et al (2019) has already shown the connection between sea‐level anomalies and circumpolar winds and our results support their discussion with in situ observations. Also, the correlation between barotropic flow and surface stress is valid, regardless of whether or not sea ice concentration/velocity were accounted for in the method used to calculate the surface stress.…”

Section: Discussionsupporting

confidence: 92%

Coherent Seasonal Acceleration of the Weddell Sea Boundary Current System Driven by Upstream Winds

et al. 2020

View full text Add to dashboard Cite

The Weddell Sea is of global importance in the formation of dense bottom waters associated with sea ice formation and ocean-ice sheet interaction occurring on the shelf areas. In this context, the Weddell Sea boundary current system (BCS) presents a major conduit for transporting relatively warm water to the Weddell Sea ice shelves and for exporting some modified form of Wedell Sea deep and bottom waters into the open ocean. This study investigates the downstream evolution of the structure and the seasonality of the BCS along the Weddell Sea continental slope, combining ocean data collected for the past two decades at three study locations. The interannual-mean geostrophic flow, which follows planetary potential vorticity contours, shifts from being surface intensified to bottom intensified along stream. The shift occurs due to the densification of water masses and the decreasing surface stress that occurs westward, toward the Antarctic Peninsula. A coherent along-slope seasonal acceleration of the barotropic flow exists, with maximum speed in austral autumn and minimum speed in austral summer. The barotropic flow significantly contributes to the seasonal variability in bottom velocity along the tip of the Antarctic Peninsula. Our analysis suggests that the winds on the eastern/northeastern side of the gyre determines the seasonal acceleration of the barotropic flow. In turn, they might control the export of Weddell Sea Bottom Water on seasonal time scales. The processes controlling the baroclinic seasonality of the flow need further investigation. Plain Language Summary In the Weddell Sea, large amounts of seawater are cooled to become dense and sink, carrying signals of human-induced changes such as atmospheric carbon into the abyss of the ocean. Understanding the variability of the ocean currents at the Antarctic continental margin is critical because it controls both the export of the dense water formed in these areas and the access of warm water that may melt the Antarctic ice sheet. This study investigates the structure and the seasonality of the flow at the continental margin in the Atlantic sector of the Southern Ocean, using in situ observations upstream and downstream of the dense water formation regions. Following the bathymetry, ocean currents flow from East to West along the continental shelf edge. As water densifies along this path, the flow speed changes from being maximum at the ocean surface to be maximum at the bottom. The depth-averaged current varies with a synchronized seasonality along the continental shelf break, reaching a maximum in austral autumn. Our analysis suggests that the winds on the eastern/northeastern margin drives the seasonality of the depth-averaged flow along the shelf break, significantly contributing to changes in bottom velocity near the export region.

show abstract

Section: Discussionsupporting

confidence: 92%

Coherent Seasonal Acceleration of the Weddell Sea Boundary Current System Driven by Upstream Winds

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Here, we provide a fit-for-purpose seasonal climatology of the subpolar Southern Ocean and propose two ASF proxies to fill this gap. Beyond representing an important benchmark for the evaluation of the ocean and climate models in this critical part of the world, our results are timely and complementary to the validation and usage of the currently growing development of satellite altimetrybased products of sea surface height in the sea ice sectors, which will undoubtedly bring an important new sight on ASF dynamics in the coming years (Armitage et al 2018;Dotto et al 2018;Naveira Garabato et al 2019).…”

Section: Discussionmentioning

confidence: 92%

Seasonal Variation of the Antarctic Slope Front Occurrence and Position Estimated from an Interpolated Hydrographic Climatology

Pauthenet

Sallée

Schmidtko

et al. 2021

Journal of Physical Oceanography

View full text Add to dashboard Cite

The Antarctic Slope Front (ASF) is a fundamental feature of the subpolar Southern Ocean that is still poorly observed. In this study we build a statistical climatology of the temperature and salinity fields of the upper 380 m of the Antarctic margin. We use a comprehensive compilation of observational datasets including the profiles gathered by instrumented marine mammals. The mapping method consists first of a decomposition in vertical modes of the combined temperature and salinity profiles. Then the resulting principal components are optimally interpolated on a regular grid and the monthly climatological profiles are reconstructed, providing a physically plausible representation of the ocean. The ASF is located with a contour method and a gradient method applied on the temperature field, two complementary approaches that provide a complete view of the ASF structure. The front extends from the Amundsen Sea to the eastern Weddell Sea and closely tracks the continental shelf break. It is associated with a sharp temperature gradient that is stronger in Winter and weaker in Summer. The emergence of the front in the Amundsen and Bellingshausen sector appears seasonally variable (slightly more westward in Winter than in Summer). The investigation of the density gradients across the shelf break indicates a Winter slowdown of the baroclinic component of the Antarctic Slope Current at the near-surface, in contrast with the seasonal variability of the temperature gradient.

show abstract

“…Indeed, the lower‐frequency variability in the barotropic velocities decreases with the presence of sea ice, suggesting that atmospheric forcing is (at least in part) important. The low‐frequency variability could be related to wind‐driven changes on the continental slope, either linked to local winds (Dotto et al., 2019) or large‐scale wind forcing (Naveira Garabato et al., 2019).…”

Section: Summary and Discussionmentioning

confidence: 99%

Rates and Mechanisms of Turbulent Mixing in a Coastal Embayment of the West Antarctic Peninsula

et al. 2021

Self Cite

View full text Add to dashboard Cite

Ice shelves in the West Antarctic sector are experiencing the greatest mass loss anywhere in Antarctica, with basal melt rates of up to ∼5 m yr −1 (Rignot et al., 2013). The melting and thinning of these floating tongues of land-based ice cause the grounded glaciers that feed them to accelerate, contributing significantly to sea level rise (Dupont & Alley, 2005;Rott et al., 2002). The West Antarctic Peninsula (WAP) also contains hundreds of marine-terminating glaciers, the majority of which are retreating, with the potential to further raise global sea level (Cook et al., 2016;Huss & Farinotti, 2014). The ice shelf and glacial melting have been attributed to an increased intrusion of warm, saline Circumpolar Deep Water (CDW), which originates in the mid-layers of the Antarctic Circumpolar Current (ACC; Cook et al., 2016;Jacobs et al., 1996). Off

show abstract

Phased Response of the Subpolar Southern Ocean to Changes in Circumpolar Winds

Cited by 28 publications

References 48 publications

Coherent Seasonal Acceleration of the Weddell Sea Boundary Current System Driven by Upstream Winds

Coherent Seasonal Acceleration of the Weddell Sea Boundary Current System Driven by Upstream Winds

Seasonal Variation of the Antarctic Slope Front Occurrence and Position Estimated from an Interpolated Hydrographic Climatology

Rates and Mechanisms of Turbulent Mixing in a Coastal Embayment of the West Antarctic Peninsula

Contact Info

Product

Resources

About