The sea-air CO2 net fluxes in the South Atlantic Ocean and the role played by Agulhas eddies

Orselli, Iole B.M.; Kerr, Rodrigo; Azevedo, José Luiz Lima de; Galdino, Felippe; Araújo, Moacyr; Garcia, Carlos Alberto Eiras

doi:10.1016/j.pocean.2018.10.006

Cited by 19 publications

(43 citation statements)

References 84 publications

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“…As expected, the pH changes observed in the South Atlantic Ocean for the deep and bottom layers are smaller than all other layers, namely, −0.0010/−0.0000 yr −1 for the upper and lower varieties of CDW, −0.0005/−0.0000 yr −1 for upper and lower varieties of NADW, and −0.0000 yr −1 for AABW e.g., [3,5,6]. Additionally, Orselli et al [34] observed that the Agulhas eddies are capable of removing more CO 2 from the atmosphere than their surrounding waters. This intensification of CO 2 absorption at the sea surface is governed mainly by physical processes when the eddy is located in the Eastern basin of the South Atlantic Ocean.…”

Section: Introductionmentioning

confidence: 90%

“…The first leg (TAII_01) was conducted from October 24th to November 25th along 35 • S (from Rio Grande, Brazil, to Cape Town, South Africa) [38], and the second leg (TAII_02) was conducted from December 2nd to December 22nd in a Southwestern-Northeastern section (from Cape Town, South Africa, to Rio de Janeiro, Brazil). The FORSA cruise occurred in 2015 on board the Brazilian Navy RV, NPqHo Vital de Oliveira from June 27th to July 15th in a Southwestern-Northeastern section (from Cape Town, to South Africa to Arraial do Cabo, to Brazil) [34,39]. Along these cruise tracks, hydrographic conductivity-temperature-depth (CTD) stations were sampled: 93 in 2011 during the TAII and 12 in 2015 during the FORSA cruise.…”

Section: Cruises Surveysmentioning

confidence: 99%

“…In addition to physical data, discrete seawater samples were collected for chemical and biological analyses, which included dissolved oxygen (DO), phytoplankton pigments, and dissolved inorganic nutrients, using a combined Sea-Bird CTD/Carrousel 911+system ® equipped with 12 five liter and 24 twelve liter Niskin bottles for the TAII and FORSA cruises, respectively. We conducted continuous measurements when crossing six Agulhas eddies during the FORSA cruise [34], but in this work, we present the results from three of them, i.e., those in which CTD stations were performed throughout the water column. The TAII and FORSA datasets are available by request.…”

Section: Cruises Surveysmentioning

confidence: 99%

“…This intensification of CO 2 absorption at the sea surface is governed mainly by physical processes when the eddy is located in the Eastern basin of the South Atlantic Ocean. However, biological processes also influence the CO 2 uptake when these structures move to the Western basin [34].…”

Section: Introductionmentioning

confidence: 99%

“…Motivated by the facts that the Agulhas eddies carry surface to intermediate waters from the Indian Ocean to the South Atlantic Ocean [21,22], and because these structures are prone to absorb more CO 2 than the surrounding waters [34], we investigate their role in ocean biogeochemistry, which is still a matter of interest e.g., [35,36]. Thus, we propose: (i) to model the marine carbonate parameters in the South Atlantic Ocean, (ii) to quantify the C ant content in the 13 identified Agulhas eddies, and (iii) to investigate the impact of the Agulhas eddies on the ocean acidification state.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Agulhas Eddies on Absorption and Transport of Anthropogenic Carbon in the South Atlantic Ocean

Orselli

Goyet²,

Kerr

et al. 2019

Climate

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The South Atlantic Ocean is currently undergoing significant alterations due to climate change. This region is important to the global carbon cycle, but marine carbon data are scarce in this basin. Additionally, this region is influenced by Agulhas eddies. However, their effects on ocean biogeochemistry are not yet fully understood. Thus, we aimed to model the carbonate parameters in this region and investigate the anthropogenic carbon (Cant) content in 13 eddies shed by the Agulhas retroflection. We used in situ data from the CLIVAR/WOCE/A10 section to elaborate total dissolved inorganic carbon (CT) and total alkalinity (AT) models and reconstruct those parameters using in situ data from two other Brazilian initiatives. Furthermore, we applied the Tracer combining Oxygen, inorganic Carbon, and total Alkalinity (TrOCA) method to calculate the Cant, focusing on the 13 identified Agulhas eddies. The CT and AT models presented root mean square errors less than 1.66 and 2.19 μmol kg−1, indicating Global Ocean Acidification Observing Network climate precision. The Cant content in the Agulhas eddies was 23% higher than that at the same depths of the surrounding waters. We observed that Agulhas eddies can play a role in the faster acidification of the South Atlantic Central Water.

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Section: Introductionmentioning

confidence: 90%

Section: Cruises Surveysmentioning

confidence: 99%

Section: Cruises Surveysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Effect of Agulhas Eddies on Absorption and Transport of Anthropogenic Carbon in the South Atlantic Ocean

Orselli

Goyet²,

Kerr

et al. 2019

Climate

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The impact of a Southern Ocean cyclonic eddy on mesopelagic micronekton

Penna

Llort

Moreau³

et al. 2021

Preprint

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Mesoscale eddies shape the foraging ecology of predators such as marine mammals and seabirds. A growing number of animal tracking studies show that predators alter their swimming, diving, and foraging behavior within mesoscale eddies. However, little is known about how Southern Ocean eddies influence the distribution of mesopelagic micronekton (fish, squid, and crustaceans), which are major prey items of megafauna. Studies in other oceanic regions have found that eddies can influence the abundance and community composition of micronekton. Here, we analyze acoustic observations from a 14-day survey of a cyclonic mesoscale eddy, its surrounding waters, and the Polar Frontal Zone (PFZ) waters where the eddy formed. We report and interpret spatial patterns of acoustic backscatter at 18 and 75 kHz, proxies indicating combined changes in species, size, and abundance of micronekton. We find that the vertical distribution of acoustic backscatter matched the underwater light conditions characteristic of the eddy core, periphery, and surrounding waters, at scales smaller than 10 km. The median water-column integrated acoustic backscatter values in the eddy core were only half of those measured in the Sub-Antarctic Zone waters surrounding the eddy, but similar to those measured in the PFZ, where the eddy originated 27 days prior. These results suggest that, as for physical and chemical tracers, the eddy maintained its biological characteristics from its source waters creating a unique habitat compared to its surroundings. Plain Language SummaryMesoscale eddies are rotating currents that are everywhere in the ocean.They are typically tens to one or two hundred km across, with lifetimes spanning weeks to months. Mesoscale eddies have a dramatic impact on the patterns of primary production in the open ocean, the transport of heat and salt across oceanic regions, global biogeochemical cycles, and the feeding behavior of marine predators such as pinnipeds, sharks, billfishes, and seabirds. In this study, we used underwater acoustic measurements to evaluate the effects of a Southern Ocean mesoscale eddy on the distribution of deep water micronekton, a diverse group of small animals including fish, crustacea, and squids. We found that the abundance and vertical distribution of micronekton inside the eddy differed from the surrounding waters. Micronekton distribution was instead more similar to where the eddy had originated a month prior to our sampling. Our results suggest that mesoscale eddies can maintain their biological characteristics from their source waters, creating a unique habitat compared to surrounding waters.

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Source waters contribution to the tropical Atlantic central layer: New insights on the Indo-Atlantic exchanges

Azar

Piñango

Wallner-Kersanach

et al. 2021

Deep Sea Research Part I: Oceanographic Research Papers

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The sea-air CO2 net fluxes in the South Atlantic Ocean and the role played by Agulhas eddies

Cited by 19 publications

References 84 publications

The Effect of Agulhas Eddies on Absorption and Transport of Anthropogenic Carbon in the South Atlantic Ocean

The Effect of Agulhas Eddies on Absorption and Transport of Anthropogenic Carbon in the South Atlantic Ocean

The impact of a Southern Ocean cyclonic eddy on mesopelagic micronekton

Source waters contribution to the tropical Atlantic central layer: New insights on the Indo-Atlantic exchanges

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