Southern Ocean carbon-wind stress feedback

Bronselaer, Ben; Zanna, Laure; Munday, David R.; Lowe, Jason

doi:10.1007/s00382-017-4041-y

Cited by 9 publications

(6 citation statements)

References 49 publications

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“…Although the mean p CO 2 differs substantially between basins, particularly in the PFZ, the amplitude of the seasonal cycle, as well as the thermal and nonthermal components of p CO 2 variability, are equivalent across sectors within each frontal zone (Figure S2b in Supporting Information S1). Thus, preferential outgassing in the Indo‐Pacific must result from the processes that set the mean surface p CO 2 value, namely, the balance between physical transport of carbon to the mixed layer and biological drawdown (Bronselaer et al., 2018).…”

Section: Resultsmentioning

confidence: 99%

Indo‐Pacific Sector Dominates Southern Ocean Carbon Outgassing

Prend

Gray

Talley

et al. 2022

Global Biogeochemical Cycles

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The Southern Ocean accounts for a disproportionately large percentage of the total oceanic anthropogenic carbon uptake, which results from the region's unique role in the global overturning circulation (Frölicher et al., 2015;Khatiwala et al., 2009). In the southern portion of the Antarctic Circumpolar Current (ACC), deep water returns to the upper ocean via wind-driven upwelling and is transformed into northward-flowing intermediate and bottom waters (J. Marshall & Speer, 2012). These upwelled deep waters have been isolated from the atmosphere since preindustrial times, and thus are poised both to absorb anthropogenic CO 2 and to release natural carbon that has accumulated over centuries through the remineralization of organic matter (Lovenduski et al., 2008). The net air-sea carbon exchange in the Southern Ocean is, therefore, a balance between opposing processes of carbon uptake and outgassing (DeVries et al., 2017;Gruber et al., 2019).Both uptake of anthropogenic CO 2 and outgassing of natural carbon are fundamentally tied to the physical transport of water between the surface mixed layer and ocean interior. While the circulation of the Southern Ocean has

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Section: Resultsmentioning

confidence: 99%

Indo‐Pacific Sector Dominates Southern Ocean Carbon Outgassing

Prend

Gray

Talley

et al. 2022

Global Biogeochemical Cycles

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“…This outgassing variability has been linked to climate-mode forced variations in wind-driven upwelling that comprises the surfacing of deep waters with high concentrations in dissolved inorganic carbon (DIC) resulting in widespread but variable outgassing of CO 2 in the subpolar region, which counteracts the CO 2 uptake flux 2 , 9 , 10 . However, it is not well understood what role the daily-to-seasonal physics of the surface mixed layer, the critical boundary between the atmosphere and the upwelled reservoir of DIC, plays in modulating the magnitude of this outgassing flux 11 , 12 .…”

Section: Introductionmentioning

confidence: 99%

Storms drive outgassing of CO2 in the subpolar Southern Ocean

Nicholson¹,

Fer

Plessis

et al. 2022

Nat Commun

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The subpolar Southern Ocean is a critical region where CO2 outgassing influences the global mean air-sea CO2 flux (FCO2). However, the processes controlling the outgassing remain elusive. We show, using a multi-glider dataset combining FCO2 and ocean turbulence, that the air-sea gradient of CO2 (∆pCO2) is modulated by synoptic storm-driven ocean variability (20 µatm, 1–10 days) through two processes. Ekman transport explains 60% of the variability, and entrainment drives strong episodic CO2 outgassing events of 2–4 mol m−2 yr−1. Extrapolation across the subpolar Southern Ocean using a process model shows how ocean fronts spatially modulate synoptic variability in ∆pCO2 (6 µatm2 average) and how spatial variations in stratification influence synoptic entrainment of deeper carbon into the mixed layer (3.5 mol m−2 yr−1 average). These results not only constrain aliased-driven uncertainties in FCO2 but also the effects of synoptic variability on slower seasonal or longer ocean physics-carbon dynamics.

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“…A range of tracer budgets have been used for this purpose across diverse space and time scales. As the necessary data is more readily available, there have been numerous DIC budgets constructed from model output, including from coupled models (Dufour et al., 2013; Hauck et al., 2013; Levy et al., 2013), idealized models (Bronselaer et al., 2018) and data‐assimilating models (Carroll et al., 2022; DeVries, 2014; Jersild & Ito, 2020; Rosso et al., 2017). However, these model‐based budgets often average the entire ocean south of a given latitude (usually 44°S) and are computed over a fixed depth.…”

Section: Introductionmentioning

confidence: 99%

Carbon Outgassing in the Antarctic Circumpolar Current Is Supported by Ekman Transport From the Sea Ice Zone in an Observation‐Based Seasonal Mixed‐Layer Budget

Sauvé,

Gray,

Prend

et al. 2023

JGR Oceans

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Despite its importance for the global cycling of carbon, there are still large gaps in our understanding of the processes driving annual and seasonal carbon fluxes in the high‐latitude Southern Ocean. This is due in part to a historical paucity of observations in this remote, turbulent, and seasonally ice‐covered region. Here, we use autonomous biogeochemical float data spanning 6 full seasonal cycles and with circumpolar coverage of the Southern Ocean, complemented by atmospheric reanalysis, to construct a monthly climatology of the mixed layer budget of dissolved inorganic carbon (DIC). We investigate the processes that determine the annual mean and seasonal cycle of DIC fluxes in two different zones of the Southern Ocean—the Sea Ice Zone (SIZ) and Antarctic Southern Zone (ASZ). We find that, annually, mixing with carbon‐rich waters at the base of the mixed layer supplies DIC which is, in the ASZ, either used for net biological production or outgassed to the atmosphere. In contrast, in the SIZ, where carbon outgassing and the biological pump are weaker, the surplus of DIC is instead advected northward to the ASZ. In other words, carbon outgassing in the southern Antarctic Circumpolar Current (ACC), which has been attributed to remineralized carbon from deep water upwelled in the ACC, is also due to the wind‐driven transport of DIC from the SIZ. These results stem from the first observation‐based carbon budget of the circumpolar Southern Ocean and thus provide a useful benchmark to evaluate climate models, which have significant biases in this region.

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Southern Ocean carbon-wind stress feedback

Cited by 9 publications

References 49 publications

Indo‐Pacific Sector Dominates Southern Ocean Carbon Outgassing

Indo‐Pacific Sector Dominates Southern Ocean Carbon Outgassing

Storms drive outgassing of CO2 in the subpolar Southern Ocean

Carbon Outgassing in the Antarctic Circumpolar Current Is Supported by Ekman Transport From the Sea Ice Zone in an Observation‐Based Seasonal Mixed‐Layer Budget

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