Southern Ocean Biogeochemical Float Deployment Strategy, With Example From the Greenwich Meridian Line (GO‐SHIP A12)

Talley, Lynne D.; Rosso, Isabella; Kamenkovich, Igor; Mazloff, Matthew R.; Wang, Jinbo; Boss, Emmanuel; Gray, Alison R.; Johnson, Kenneth S.; Key, Robert M.; Riser, Stephen C.; Williams, Nancy L.; Sarmiento, Jorge L.

doi:10.1029/2018jc014059

Cited by 30 publications

(26 citation statements)

References 107 publications

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“…The Southern Ocean is a critical region to the global carbon cycle, but our understanding of the regional carbon cycle is still limited. Observations have been highly seasonal until recently, where autonomous floats are starting to provide continuous coverage (Talley et al, 2019). The Drake Passage is the only region in the Southern Ocean with consistent year‐round sampling, making it an ideal region to investigate pCO 2 seasonality, but numerical models, including ours, still cannot fully reproduce the observed pCO 2 time series.…”

Section: Discussionmentioning

confidence: 99%

Physical and Biological Controls of the Drake Passage pCO₂ Variability

Jersild

Ito

2020

Global Biogeochemical Cycles

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The Southern Ocean is an important region of ocean carbon uptake, and observations indicate its air-sea carbon flux fluctuates from seasonal to decadal timescales. Carbon fluxes at regional scales remain highly uncertain due to sparse observation and intrinsic complexity of the biogeochemical processes. The objective of this study is to better understand the mechanisms influencing variability of carbon uptake in the Drake Passage. A regional circulation and biogeochemistry model is configured at the lateral resolution of 10 km, which resolves larger mesoscale eddies where the typical Rossby deformation radius is  (50 km). We use this model to examine the interplay between mean and eddy advection, convective mixing, and biological carbon export that determines the surface dissolved inorganic carbon and partial pressure of carbon dioxide variability. Results are validated against in situ observations, demonstrating that the model captures general features of observed seasonal to interannual variability. The model reproduces the two major fronts: Polar Front (PF) and Subantarctic Front (SAF), with locally elevated level of eddy kinetic energy and lateral eddy carbon flux, which play prominent roles in setting the spatial pattern, mean state and variability of the regional carbon budget. The uptake of atmospheric CO 2 , vertical entrainment during cool seasons, and mean advection are the major carbon sources in the upper 200 m of the region. These sources are balanced by the biological carbon export during warm seasons and mesoscale eddy transfer. Comparing the induced advective carbon fluxes, mean flow dominates in magnitude, however, the amplitude of variability is controlled by the eddy flux. Plain Language Summary The Southern Ocean, which surrounds Antarctica, is a critical component of global climate and carbon cycling. The Drake Passage is the region south of the tip of South America. It is one of the most well sampled sectors of the Southern Ocean, and the narrowest and southernmost constriction of the Antarctic Circumpolar Current. While the region is an overall carbon sink, its carbon uptake can fluctuate over time, and its uncertainty comes from sparse observations and the complex nature of the contributing processes. We use a regional ocean circulation and biogeochemical model to better understand the influencing mechanisms on the variability of carbon uptake to the region. Model results demonstrate that absorbed atmospheric carbon, strong wintertime mixing and vertical water movement, and mean ocean currents are the major source of carbon in the upper 200 m of the Drake Passage. These inputs of carbon into the ocean are balanced by smaller scale (10-100 km) movements called ocean eddies and the biological drawdown of carbon. This research allows for better comprehension of regional carbon fluxes and analysis of biophysical dynamics influencing the annual and interannual fluctuation.

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Section: Discussionmentioning

confidence: 99%

Physical and Biological Controls of the Drake Passage pCO₂ Variability

Jersild

Ito

2020

Global Biogeochemical Cycles

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“…This study uses in situ data from autonomous biogeochemical floats deployed by the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project (Talley et al, 2019). SOCCOM floats measure temperature, salinity, pressure, dissolved oxygen, nitrate, pH, fluorescence, and backscatter over the top 2,000 m of the water column every 10 days.…”

Section: Methodsmentioning

confidence: 99%

Weddell Sea Phytoplankton Blooms Modulated by Sea Ice Variability and Polynya Formation

Berg

Prend

Campbell

et al. 2020

Geophysical Research Letters

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Seasonal sea ice retreat is known to stimulate Southern Ocean phytoplankton blooms, but depth‐resolved observations of their evolution are scarce. Autonomous float measurements collected from 2015–2019 in the eastern Weddell Sea show that spring bloom initiation is closely linked to sea ice retreat timing. The appearance and persistence of a rare open‐ocean polynya over the Maud Rise seamount in 2017 led to an early bloom and high annual net community production. Widespread early ice retreat north of Maud Rise in 2017, however, had a similar effect, suggesting that the polynya most impacted the timing of bloom initiation. Still, higher productivity rates at Maud Rise relative to the surrounding region are observed in all years, likely supported by flow‐topography interactions. The longer growing season in 2017–2018 also allowed for separation of distinct spring and fall bloom signals, the latter of which was primarily subsurface and associated with mixed‐layer deepening.

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“…Another promising development is the deployment of Argo floats equipped with ice avoidance software. These floats are also beginning to carry sensors that measure nitrate, oxygen, pH, and fluorescence, and several have already been deployed in the WG (Briggs et al, ; Talley et al, ). Adding the ability to acoustically track the location of these floats when they are under the seasonal ice will improve their utility (Chamberlain et al, ).…”

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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143

147

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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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Southern Ocean Biogeochemical Float Deployment Strategy, With Example From the Greenwich Meridian Line (GO‐SHIP A12)

Cited by 30 publications

References 107 publications

Physical and Biological Controls of the Drake Passage pCO₂ Variability

Physical and Biological Controls of the Drake Passage pCO₂ Variability

Weddell Sea Phytoplankton Blooms Modulated by Sea Ice Variability and Polynya Formation

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

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Southern Ocean Biogeochemical Float Deployment Strategy, With Example From the Greenwich Meridian Line (GO‐SHIP A12)

Cited by 30 publications

References 107 publications

Physical and Biological Controls of the Drake Passage pCO2 Variability

Physical and Biological Controls of the Drake Passage pCO2 Variability

Weddell Sea Phytoplankton Blooms Modulated by Sea Ice Variability and Polynya Formation

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

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Product

Resources

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Physical and Biological Controls of the Drake Passage pCO₂ Variability

Physical and Biological Controls of the Drake Passage pCO₂ Variability