Importance of the Antarctic Slope Current in the Southern Ocean Response to Ice Sheet Melt and Wind Stress Change

Beadling, R. L.; Krasting, John P.; Griffies, Stephen M.; Hurlin, William J.; Bronselear, B.; Russell, J. L.; MacGilchrist, Graeme A.; Tesdal, Jan‐Erik; Winton, Michael

doi:10.1029/2021jc017608

Cited by 20 publications

(103 citation statements)

References 90 publications

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“…As both models share many characteristics, we review similarities and key differences relevant for the SO. We limit our description here to the ocean and sea ice components in each model as Beadling et al (2022) and references therein, including Held et al (2019) and Dunne et al (2020), provide complete model component descriptions for CM4 and ESM4.…”

Section: Modelsmentioning

confidence: 99%

“…We investigated the steady-state connections between WMT, MOC, and ocean ventilation in the SO and their transient response to idealized freshwater and wind stress perturbations. The perturbation experiments are designed to represent the increased melting of the Antarctic Ice Sheet (AIS) and an increase and poleward shift of the Southern Hemisphere westerlies projected to occur near the middle of the twenty-first century under a high emissions scenario (Beadling et al, 2022;DeConto & Pollard, 2016;Gregory et al, 2016). The four experiments analyzed in this study include (1) the previously spun-up pre-industrial control (piControl) simulation contributed to CMIP6 (Eyring et al, 2016) (referred to hereafter as Control), ( 2) an experiment with a 0.1 Sv freshwater perturbation entering at the Antarctic coast (referred to hereafter as Antwater), (3) an experiment imposing zonal and meridional wind stress perturbations (referred to here-after as Stress), and (4) an experiment that simultaneously imposes the freshwater and momentum perturbations (referred to as AntwaterStress).…”

Section: Experimental Designmentioning

confidence: 99%

“…All perturbation experiments branch from each model's Control integration. The experiments in this study are identical to those described in Beadling et al (2022) and readers are referred to the experimental design described therein, but we summarize several key points here.…”

Section: Experimental Designmentioning

confidence: 99%

“…Studies utilizing idealized perturbation experiments have either focused on the response to wind stress change (Spence, Sebille, et al, 2014;Hogg et al, 2017;Bishop et al, 2016;Downes et al, 2017) or AIS melting individually (Fogwill et al, 2015;Lago & England, 2019;Moorman et al, 2020). However, recent work by Bronselaer et al (2020) and Beadling et al (2022), highlight that both the projected wind stress changes and AIS melting are critical to consider together when investigating the transient response of the SO, given their competing effects on SO ventilation and the thermal response on the Antarctic shelf. Previous studies suggest opposing imprints of wind and AIS melt perturbations on SO water masses and circulation, with contributions that are likely not a simple linear combination of separate perturbation responses (Dias et al, 2021;Beadling et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…However, recent work by Bronselaer et al (2020) and Beadling et al (2022), highlight that both the projected wind stress changes and AIS melting are critical to consider together when investigating the transient response of the SO, given their competing effects on SO ventilation and the thermal response on the Antarctic shelf. Previous studies suggest opposing imprints of wind and AIS melt perturbations on SO water masses and circulation, with contributions that are likely not a simple linear combination of separate perturbation responses (Dias et al, 2021;Beadling et al, 2022). This non-linear response precludes the possibility of attributing changes in the SO MOC to individual contributions from AIS melt and wind stress change in previous studies that have not considered both forcings in tandem.…”

Section: Introductionmentioning

confidence: 99%

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The nonlinear impact of surface forcing changes on bottom water formation and overturning in the Southern Ocean

Tesdal

MacGilchrist

Beadling

et al. 2022

Preprint

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Two coupled climate models, differing primarily in horizontal resolution and treatment of mesoscale eddies, were used to assess the impact of perturbations in wind stress and Antarctic ice sheet (AIS) melting on the Southern Ocean meridional overturning circulation (SO MOC), which plays an important role in global climate regulation. The largest impact is found in the SO MOC lower limb, associated with the formation of Antarctic Bottom Water (AABW), which in both models is enhanced by wind and weakened by AIS meltwater perturbations. Even though both models under the AIS melting perturbation show similar AABW transport reductions of 4-5 Sv (50-60%), the volume deflation of AABW south of 30@S is four times greater in the higher resolution simulation (-20 vs -5 Sv). Water mass transformation (WMT) analysis reveals that surface-forced dense water formation on the Antarctic shelf is absent in the higher resolution and reduced by half in the lower resolution model in response to the increased AIS melting. However, the decline of the AABW volume (and its inter-model difference) far exceeds the surface-forced WMT changes alone, which indicates that the divergent model responses arise from interactions between changes in surface forcing and interior mixing processes. This model divergence demonstrates an important source of uncertainty in climate modeling, and indicates that accurate shelf processes together with scenarios accounting for AIS melting are necessary for robust projections of the deep ocean's response to anthropogenic forcing and role as the largest sink in Earth's energy budget.

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Section: Modelsmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The nonlinear impact of surface forcing changes on bottom water formation and overturning in the Southern Ocean

Tesdal

MacGilchrist

Beadling

et al. 2022

Preprint

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Future Response of Antarctic Continental Shelf Temperatures to Ice Shelf Basal Melting and Calving

Thomas,

Ridley,

Smith

et al. 2023

Geophysical Research Letters

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We investigate feedbacks between subsurface continental shelf ocean temperatures and Antarctic glacial melt using a coupled climate model. The model was forced with SSP5‐8.5 and an uncoupled projection of basal melt and calving fluxes. SSP5‐8.5 forcing with fixed pre‐industrial glacial melt warms all continental shelves, such that historically “cool” and “fresh” shelves transition to “warm.” Additional glacial melt, added at depth, cools the Eastern Ross, Amundsen, and Bellingshausen seas, suggesting a negative feedback on basal melt—a novel result for a coarse resolution coupled model. From the Weddell Sea, along East Antarctica, and into the western Ross Sea—where continental shelves transition to a “warm” state—additional glacial melt increases temperatures at the continental shelf sea floor, suggesting a positive feedback. The sign of the glacial melt–subsurface temperature feedback is critically dependent on continental shelf properties, climate state, and the vertical distribution of glacial melt inputs.

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Pathways and Timescales of Connectivity Around the Antarctic Continental Shelf

et al. 2023

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The Antarctic Slope Current (ASC) and Antarctic Coastal Current advect heat, freshwater, nutrients, and biological organisms westward around the Antarctic margin, providing a connective link between different sectors of the continental shelf. Yet the strength and pathways of connectivity around the continent, and the timescales of advection, remain poorly understood. We use daily velocity fields from a global high‐resolution ocean‐sea ice model, combined with Lagrangian particle tracking, to shed light on these timescales and improve our understanding of circumpolar connectivity around Antarctica. Virtual particles were released along vertical transects over the continental shelf every 5 days for a year and were tracked forward in time for 21 years. Analysis of the resulting particle trajectories highlights that the West Antarctic sector has widespread connectivity with all regions of the Antarctic shelf. Advection around the continent is typically rapid with peak transit times of 1–5 years for particles to travel 90° of longitude downstream. The ASC plays a key role in driving connectivity in East Antarctica and the Weddell Sea, while the Coastal Current controls connectivity in West Antarctica, the eastern Antarctic Peninsula, and along the continental shelf east of Prydz Bay. Connectivity around the shelf is impeded in two main locations, namely, the tip of the Antarctic Peninsula and Cape Adare in the Ross Sea, where significant export of water from the continental shelf is found. These findings help to understand the locations and timescales over which anomalies, such as meltwater from the Antarctic Ice Sheet, can be redistributed downstream.

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Importance of the Antarctic Slope Current in the Southern Ocean Response to Ice Sheet Melt and Wind Stress Change

Cited by 20 publications

References 90 publications

The nonlinear impact of surface forcing changes on bottom water formation and overturning in the Southern Ocean

The nonlinear impact of surface forcing changes on bottom water formation and overturning in the Southern Ocean

Future Response of Antarctic Continental Shelf Temperatures to Ice Shelf Basal Melting and Calving

Pathways and Timescales of Connectivity Around the Antarctic Continental Shelf

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