Southern Ocean [in “State of the Climate in 2020”]
TamsittSeth M. BushinskyZ LiMarcel du PlessisAnnie FoppertSarah T. GilleStephen R. RintoulElizabeth H. ShadwickAlessandro SilvanoSeth R. SuttonSebastiaan SwartBronte TilbrookNL Williams
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The Southern Ocean (SO) plays a unique role in the climate system and is responsible for 40%
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et al. 2021), and Deep Argo (Roemmich et al. 2019) have provided novel insights into seasonal
and interannual variability in SO properties and fluxes. Here, we present 2020 anomalies of SO
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Abstract Recent increases in resolution of coupled ocean‐atmosphere models have the potential to improve the representation of poleward heat transport within the climate system. Here we examine the interplay between model resolution‐dependent changes in Atlantic Ocean heat transport (AOHT) and surface heat fluxes. The different roles of changes in atmospheric and ocean resolution are isolated using three different climate models (The Centro Euro‐Mediterraneo sui Cambiamenti Climatici Climate Model 2, Hadley Centre Global Environmental Model 3 – Global Coupled configuration 2, and European Community Earth‐System Model 3.1) and comparing runs in which (a) only the ocean resolution changes, (b) only the atmosphere resolution changes, and (c) both change. Enhancing ocean resolution from eddy parameterized to eddy permitting increases the AOHT throughout the basin, values changing from 1.0 to 1.2 PW at 26°N, bringing the AOHT into the range of estimates from the RAPID observing array. This increase in AOHT is associated with higher North Atlantic sea surface temperatures and increased ocean heat loss to the atmosphere. Increasing the atmospheric resolution alone has little impact on the AOHT due to regionally compensating changes in the components of the net heat flux. Finally, in a fourth experiment the impact of resolution changes in both components and the transition to an eddy‐resolving ocean is assessed. This additional resolution increase is accompanied by a further change in the AOHT and improves agreement with observations in the tropics but not the subpolar regions. However, unlike with the increase to the eddy‐permitting ocean, when the greatest AOHT change occurs in the subtropics and subpolar region, the most significant increase now occurs in the tropics.
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Abstract The physical circulation of the Southern Ocean sets the surface concentration and thus air‐sea exchange of . However, we have a limited understanding of the three‐dimensional circulation that brings deep carbon‐rich waters to the surface. Here, we introduce and analyze a novel high‐resolution ocean model simulation with active biogeochemistry and online Lagrangian particle tracking. We focus our attention on a subset of particles with high dissolved inorganic carbon (DIC) that originate below 1,000 m and eventually upwell into the near‐surface layer (upper 200 m). We find that 71% of the DIC‐enriched water upwelling across 1,000 m is concentrated near topographic features, which occupy just 33% of the Antarctic Circumpolar Current. Once particles upwell to the near‐surface layer, they exhibit relatively uniform levels and DIC decorrelation timescales, regardless of their origin. Our results show that Southern Ocean bathymetry plays a key role in delivering carbon‐rich waters to the surface.
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The Southern Ocean plays a pivotal role in climate change by exchanging heat and carbon, and provides the primary window for the global deep ocean to communicate with the atmosphere. There has been a widespread focus on explaining atmospheric CO2 changes in terms of changes in wind forcing in the Southern Ocean. Here, we develop a dynamically-motivated metric, the residual upwelling, that measures the primary effect of Southern Ocean dynamics on atmospheric CO2 on centennial to millennial timescales by determining the communication with the deep ocean. The metric encapsulates the combined, net effect of winds and air–sea buoyancy forcing on both the upper and lower overturning cells, which have been invoked as explaining atmospheric CO2 changes for the present day and glacial-interglacial changes. The skill of the metric is assessed by employing suites of idealized ocean model experiments, including parameterized and explicitly simulated eddies, with online biogeochemistry and integrated for 10,000 years to equilibrium. Increased residual upwelling drives elevated atmospheric CO2 at a rate of typically 1–1.5 parts per million/106 m3 s−1 by enhancing the communication between the atmosphere and deep ocean. This metric can be used to interpret the long-term effect of Southern Ocean dynamics on the natural carbon cycle and atmospheric CO2, alongside other metrics, such as involving the proportion of preformed nutrients and the extent of sea ice cover.
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Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Geophysical Research Letters. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v1]The Disproportionate Role of Ocean Topography on the Upwelling of Carbon in the Southern OceanAuthorsRiley XavierBradyiDMathew EMaltrudPhillip JustinWolfram Jr.Henri FrancoisDrakeiDNicole SuzanneLovenduskiiDSee all authors Riley Xavier BradyiDCorresponding Author• Submitting AuthorUniversity of Colorado BoulderiDhttps://orcid.org/0000-0002-2309-8245view email addressThe email was not providedcopy email addressMathew E MaltrudLos Alamos National Laboratory (DOE)view email addressThe email was not providedcopy email addressPhillip Justin Wolfram Jr.Los Alamos National Laboratoryview email addressThe email was not providedcopy email addressHenri Francois DrakeiDMassachusetts Institute of TechnologyiDhttps://orcid.org/0000-0003-0135-0814view email addressThe email was not providedcopy email addressNicole Suzanne LovenduskiiDUniversity of Colorado BoulderiDhttps://orcid.org/0000-0001-5893-1009view email addressThe email was not providedcopy email address
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Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Journal of Geophysical Research - Oceans. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing an older version [v1]Go to new versionThree-dimensional Overturning Circulation Generated by Topography in the Southern Ocean and Its ImplicationsAuthorsMadeleine KYoungsiDGlenn RFlierlSee all authors Madeleine K YoungsiDCorresponding Author• Submitting AuthorNYU CourantiDhttps://orcid.org/0000-0002-3395-8165view email addressThe email was not providedcopy email addressGlenn R FlierlMITview email addressThe email was not providedcopy email address
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