Profiling Floats in SOCCOM: Technical Capabilities for Studying the Southern Ocean

Riser, Stephen C.; Swift, Dana D.; Drucker, Robert

doi:10.1002/2017jc013419

Cited by 60 publications

(62 citation statements)

References 29 publications

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“…The SOCCOM floats used in this study were APEX and BGC‐Navis (Johnson et al, ; Riser et al, ), while the SOCLIM floats were PROVBIO‐2 and PROVAL (Leymarie et al, ). All floats were equipped with CTD and bio‐optical sensors, which measured temperature, salinity, pressure, nitrate, dissolved oxygen, chlorophyll fluorescence, and optical backscatter coefficient.…”

Section: Methodsmentioning

confidence: 99%

Southern Ocean Phytoplankton Blooms Observed by Biogeochemical Floats

et al. 2019

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The spring bloom in the Southern Ocean is the rapid-growth phase of the seasonal cycle in phytoplankton. Many previous studies have characterized the spring bloom using chlorophyll estimates from satellite ocean color observations. Assumptions regarding the chlorophyll-to-carbon ratio within phytoplankton and vertical structure of biogeochemical variables lead to uncertainty in satellite-based estimates of phytoplankton carbon biomass. Here, we revisit the characterizations of the bloom using optical backscatter from biogeochemical floats deployed by the Southern Ocean Carbon and Climate Observations and Modeling and Southern Ocean and Climate Field Studies with Innovative Tools projects. In particular, by providing a three-dimensional view of the seasonal cycle, we are able to identify basin-wide bloom characteristics corresponding to physical features; biomass is low in Ekman downwelling regions north of the Antarctic Circumpolar Current region and high within and south of the Antarctic Circumpolar Current. Plain Language SummaryThe advent of satellites has allowed us to observe the ocean surface on unprecedented scale. One of the major biogeochemical findings from these observations was that phytoplankton in the Southern Ocean repeatedly went through a dramatic phase of growth every spring basin wide. Phytoplankton, however, exist not only at the ocean surface but also in the interior, generally in the top 100 m. In our study, we revisit the characterization of this spring growth using autonomous floats that vertically profile biogeochemical properties including phytoplankton concentration, providing three-dimensional estimates of phytoplankton. Our results support the conventional knowledge of there being a robust seasonal cycle in phytoplankton within and south of the Antarctic Circumpolar Current region, an energetic eastward current that wraps around Antarctica.

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Section: Methodsmentioning

confidence: 99%

Southern Ocean Phytoplankton Blooms Observed by Biogeochemical Floats

et al. 2019

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“…Successful deployments of AUVs in the pan-Arctic area provide new physical and biogeochemical insights, even in the presence of sea ice (e.g., Laney et al, 2014;Wulff et al, 2016). Nowadays, BGC-Argo floats are largely used to evaluate the NCP in different ocean basins (e.g., Bushinsky & Emerson, 2015;Hennon et al, 2016;Plant et al, 2016;Riser et al, 2018;Yang et al, 2017). Here invaluable observations over multiple years from BGC-Argo floats that sampled the SIZ of the Greenland Sea, mainly under the sea ice in winter and at the MIZ in summer, are discussed.…”

Section: Introductionmentioning

confidence: 99%

Assessing Phytoplankton Activities in the Seasonal Ice Zone of the Greenland Sea Over an Annual Cycle

et al. 2018

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In seasonal ice zones (SIZs), such as the one of the Greenland Sea, the sea ice growth in winter and subsequent melting in summer influence the phytoplankton activity. However, studies assessing phytoplankton activities over complete annual cycles and at a fine temporal resolution are lacking in this environment. Biogeochemical‐Argo floats, which are able to sample under the ice, were used to collect physical and biogeochemical data along vertical profiles and at 5‐day resolution during two complete annual cycles in the Greenland Sea SIZ. Three phytoplankton activity phases were distinct within an annual cycle: one under ice, a second at the ice edge, and a third one around an open‐water subsurface chlorophyll maximum. As expected, the light and nitrate availabilities controlled the phytoplankton activity and the establishment of these phases. On average, most of the annual net community production occurred equally under ice and at the ice edge. The open‐water subsurface chlorophyll maximum phase contribution, on the other hand, was much smaller. Phytoplankton biomass accumulation and production thus occur over a longer period than might be assumed if under ice blooms were neglected. This also means that satellite‐based estimates of phytoplankton biomass and production in this SIZ are likely underestimated. Simulations with the Arctic‐based physical‐biologically coupled SINMOD model suggest that most of the annual net community production in this SIZ results from local processes rather than due to advection of nitrate from the East Greenland and Jan Mayen Currents.

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“…Of the 12 floats, the 8 Apex floats functioned as expected, equivalent to the success rate of the global core Argo fleet (Riser et al, ), and 7 are currently providing data past their third winter cycles. One Apex float worked for 66 profiles (PFZ float 5904473) but lost buoyancy and hence telemetering capability in December 2016.…”

Section: Ps89/a12 Deployments and Outcomesmentioning

confidence: 85%

“…Each includes core Argo sensors (temperature, conductivity, and pressure) and, to the greatest extent possible, all BGC sensors (oxygen, nitrate, pH, and optical sensors—either chlorophyll fluorescence and backscatter on Apex or these plus fluorescence by color dissolved material on Navis floats), and ice avoidance software to enable winter profiling. SOCCOM follows Argo protocols for core properties (temperature, salinity, and pressure), cycling (parking at 1,000 m, profiling every 10 days from 2,000 m to the sea surface; Riser et al, ; Roemmich et al, ), and data management. SOCCOM core and BGC data are posted through the public real‐time and delayed mode Argo data stream (http://jcommops.org).…”

Section: Elements Of the Soccom Float Deployment Strategymentioning

confidence: 99%

“…A marriage between ice‐capable core Argo and maturing biogeochemical (BGC) sensing that resolves seasonal cycles in oxygen, nutrients, and carbon (Johnson et al, ) now allows us to map, quantify, and understand the unique biogeochemical and physical processes and their seasonal cycles in the Southern Ocean, where there have been almost no prior in situ winter biogeochemical observations. SOCCOM floats are BGC Argo floats (Biogeochemical‐Argo Planning Group, ), following the same protocols as core Argo floats (10‐day profiling from surface to 2,000 m, parking depth 1,000 m), with added BGC sensors (Riser et al, ). SOCCOM data are already improving forward ocean and climate models through direct comparison and state estimates that combine data and models (Russell et al, ).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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Biogeochemical Argo floats, profiling to 2,000‐m depth, are being deployed throughout the Southern Ocean by the Southern Ocean Carbon and Climate Observations and Modeling program (SOCCOM). The goal is 200 floats by 2020, to provide the first full set of annual cycles of carbon, oxygen, nitrate, and optical properties across multiple oceanographic regimes. Building from no prior coverage to a sparse array, deployments are based on prior knowledge of water mass properties, mean frontal locations, mean circulation and eddy variability, winds, air‐sea heat/freshwater/carbon exchange, prior Argo trajectories, and float simulations in the Southern Ocean State Estimate and Hybrid Coordinate Ocean Model (HYCOM). Twelve floats deployed from the 2014–2015 Polarstern cruise from South Africa to Antarctica are used as a test case to evaluate the deployment strategy adopted for SOCCOM's 20 deployment cruises and 126 floats to date. After several years, these floats continue to represent the deployment zones targeted in advance: (1) Weddell Gyre sea ice zone, observing the Antarctic Slope Front, and a decadally‐rare polynya over Maud Rise; (2) Antarctic Circumpolar Current (ACC) including the topographically steered Southern Zone chimney where upwelling carbon/nutrient‐rich deep waters produce surprisingly large carbon dioxide outgassing; (3) Subantarctic and Subtropical zones between the ACC and Africa; and (4) Cape Basin. Argo floats and eddy‐resolving HYCOM simulations were the best predictors of individual SOCCOM float pathways, with uncertainty after 2 years of order 1,000 km in the sea ice zone and more than double that in and north of the ACC.

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Profiling Floats in SOCCOM: Technical Capabilities for Studying the Southern Ocean

Cited by 60 publications

References 29 publications

Southern Ocean Phytoplankton Blooms Observed by Biogeochemical Floats

Southern Ocean Phytoplankton Blooms Observed by Biogeochemical Floats

Assessing Phytoplankton Activities in the Seasonal Ice Zone of the Greenland Sea Over an Annual Cycle

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

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