Space and time variability of the <scp>S</scp>outhern <scp>O</scp>cean carbon budget

Rosso, Isabella; Mazloff, Matthew R.; Verdy, Ariane; Talley, Lynne D.

doi:10.1002/2016jc012646

Cited by 23 publications

(37 citation statements)

References 94 publications

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“…North of the ACC, water is subducted, allowing for carbon uptake. Departures from this background pattern are due to biological productivity acting as a carbon sink or due to locations of strong currents, as shown in the B‐SOSE carbon budget analysis carried out in Rosso et al (). The mean heat flux is large wherever the circulation is meridionally steered by bathymetry (Figure b).…”

Section: Resultsmentioning

confidence: 92%

Correlation Lengths for Estimating the Large‐Scale Carbon and Heat Content of the Southern Ocean

et al. 2018

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The spatial correlation scales of oceanic dissolved inorganic carbon, heat content, and carbon and heat exchanges with the atmosphere are estimated from a realistic numerical simulation of the Southern Ocean. Biases in the model are assessed by comparing the simulated sea surface height and temperature scales to those derived from optimally interpolated satellite measurements. While these products do not resolve all ocean scales, they are representative of the climate scale variability we aim to estimate. Results show that constraining the carbon and heat inventory between 35°S and 70°S on time‐scales longer than 90 days requires approximately 100 optimally spaced measurement platforms: approximately one platform every 20° longitude by 6° latitude. Carbon flux has slightly longer zonal scales, and requires a coverage of approximately 30° by 6°. Heat flux has much longer scales, and thus a platform distribution of approximately 90° by 10° would be sufficient. Fluxes, however, have significant subseasonal variability. For all fields, and especially fluxes, sustained measurements in time are required to prevent aliasing of the eddy signals into the longer climate scale signals. Our results imply a minimum of 100 biogeochemical‐Argo floats are required to monitor the Southern Ocean carbon and heat content and air‐sea exchanges on time‐scales longer than 90 days. However, an estimate of formal mapping error using the current Argo array implies that in practice even an array of 600 floats (a nominal float density of about 1 every 7° longitude by 3° latitude) will result in nonnegligible uncertainty in estimating climate signals.

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Section: Resultsmentioning

confidence: 92%

Correlation Lengths for Estimating the Large‐Scale Carbon and Heat Content of the Southern Ocean

et al. 2018

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“…We speculate that too much sea ice formation in B‐SOSE, and therefore too much brine rejection, drives a high salinity bias south of the PF in winter, likely influencing DIC and driving the wintertime pCO 2(nonT) bias. Indeed, Rosso et al () show the large effect of DIC dilution from sea ice melt and precipitation at these southerly latitudes.…”

Section: Discussionmentioning

confidence: 97%

The Observed Seasonal Cycle of Macronutrients in Drake Passage: Relationship to Fronts and Utility as a Model Metric

et al. 2019

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The Drake Passage Time‐series (DPT) is used to quantify the spatial and seasonal variability of historically undersampled, biogeochemically relevant properties across the Drake Passage. From 2004–2017, discrete ship‐based observations of surface macronutrients (silicate, nitrate, and phosphate), temperature, and salinity have been collected 5–8 times per year as part of the DPT program. Using the DPT and Antarctic Circumpolar Current (ACC) front locations derived from concurrent expendable bathythermograph data, the distinct physical and biogeochemical characteristics of ACC frontal zones are characterized. Biogeochemical‐Argo floats in the region confirm that the near‐surface sampling scheme of the DPT robustly captures mixed‐layer biogeochemistry. While macronutrient concentrations consistently increase toward the Antarctic continent, their meridional distribution, variability, and biogeochemical gradients are unique across physical ACC fronts, suggesting a combination of physical and biological processes controlling nutrient availability and nutrient front location. The Polar Front is associated with the northern expression of the Silicate Front, marking the biogeographically relevant location between silicate‐poor and silicate‐rich waters. South of the northern Silicate Front, the silicate‐to‐nitrate ratio increases, with the sharpest gradient in silicate associated with the Southern ACC Front (i.e., the southern expression of the Silicate Front). Nutrient cycling is an important control on variability in the surface ocean partial pressure of carbon dioxide (pCO2). The robust characterization of the spatiotemporal variability of nutrients presented here highlights the utility of biogeochemical time series for diagnosing and potentially reducing biases in modeling Southern Ocean pCO2 variability, and by inference, air‐sea CO2 flux.

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“…The Biogeochemical Southern Ocean State Estimate assimilates both physical and biogeochemical observations to produce a hindcast of the carbon, oxygen, nutrients, and physical state (Verdy & Mazloff, ). Rosso et al () analyzed the upper WG area integrated carbon budget in B‐SOSE, showing that biological processes and dilution by addition of freshwater acted together to considerably draw down the carbon content in austral spring and summer. Some of this was compensated by an increase in atmospheric CO2 uptake.…”

Section: Modeling the Wgmentioning

confidence: 99%

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

Vernet

Geibert

Hoppema

et al. 2019

Reviews of Geophysics

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The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the state‐of‐the art knowledge concerning the WG from an interdisciplinary perspective, uncovering critical aspects needed to understand this system's role in shaping the future evolution of oceanic heat and carbon uptake over the next decades. The main limitations in our knowledge are related to the conditions in this extreme and remote environment, where the polar night, very low air temperatures, and presence of sea ice year‐round hamper field and remotely sensed measurements. We highlight the importance of winter and under‐ice conditions in the southern WG, the role that new technology will play to overcome present‐day sampling limitations, the importance of the WG connectivity to the low‐latitude oceans and atmosphere, and the expected intensification of the WG circulation as the westerly winds intensify. Greater international cooperation is needed to define key sampling locations that can be visited by any research vessel in the region. Existing transects sampled since the 1980s along the Prime Meridian and along an East‐West section at ~62°S should be maintained with regularity to provide answers to the relevant questions. This approach will provide long‐term data to determine trends and will improve representation of processes for regional, Antarctic‐wide, and global modeling efforts—thereby enhancing predictions of the WG in global ocean circulation and climate.

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Space and time variability of the Southern Ocean carbon budget

Cited by 23 publications

References 94 publications

Correlation Lengths for Estimating the Large‐Scale Carbon and Heat Content of the Southern Ocean

Correlation Lengths for Estimating the Large‐Scale Carbon and Heat Content of the Southern Ocean

The Observed Seasonal Cycle of Macronutrients in Drake Passage: Relationship to Fronts and Utility as a Model Metric

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

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