Article
Environmental Sciences
Keith B. Rodgers, Jorg Schwinger, Andrea J. Fassbender, Peter Landschutzer, Ryohei Yamaguchi, Hartmut Frenzel, Karl Stein, Jens Daniel Mueller, Nadine Goris, Sahil Sharma, Seth Bushinsky, Thi-Tuyet-Trang Chau, Marion Gehlen, M. Angeles Gallego, Lucas Gloege, Luke Gregor, Nicolas Gruber, Judith Hauck, Yosuke Iida, Masao Ishii, Lydia Keppler, Ji-Eun Kim, Sarah Schlunegger, Jerry Tjiputra, Katsuya Toyama, Pradeebane Vaittinada Ayar, Anton Velo
Summary: The study reveals discrepancies in the estimation of the seasonal cycle of surface ocean pCO(2) flux between models and observations. Over the past three decades, the amplitude of the pCO(2) seasonal cycle has increased globally, with different drivers in different regions. Human-induced CO2 absorption is the dominant driver in subtropical and Southern Ocean biomes, while Cant invasion and climate change play a combined role in other biomes. The study highlights the importance of sustained high-quality measurements for accurately capturing the seasonal variability of pCO(2) over certain regions.
GLOBAL BIOGEOCHEMICAL CYCLES
(2023)
Article
Environmental Sciences
Judith Hauck, Luke Gregor, Cara Nissen, Lavinia Patara, Mark Hague, Precious Mongwe, Seth Bushinsky, Scott C. Doney, Nicolas Gruber, Corinne Le Quere, Manfredi Manizza, Matthew Mazloff, Pedro M. S. Monteiro, Jens Terhaar
Summary: Based on data from the RECCAP2 project, we assessed the CO2 uptake in the Southern Ocean and found that it is only half of what was previously estimated. Furthermore, there is a knowledge gap in understanding the increase in CO2 sink since 2000. It is important to improve our observation and understanding of the drivers of the carbon cycle in order to accurately assess the Southern Ocean's role in CO2 absorption.
GLOBAL BIOGEOCHEMICAL CYCLES
(2023)
Article
Geosciences, Multidisciplinary
Riley X. Brady, Mathew E. Maltrud, Phillip J. Wolfram, Henri F. Drake, Nicole S. Lovenduski
Summary: This study used a high-resolution ocean model simulation to show that Southern Ocean bathymetry plays a key role in bringing carbon-rich deep waters to the surface. The results indicate that 71% of carbon-enriched water upwelling across 1,000 m is concentrated near topographic features, and once upwelled to the near-surface layer, they exhibit relatively uniform pCO2 levels and DIC decorrelation timescales.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Oceanography
Manami Tozawa, Daiki Nomura, Shin-ichiro Nakaoka, Masaaki Kiuchi, Kaihe Yamazaki, Daisuke Hirano, Shigeru Aoki, Hiroko Sasaki, Hiroto Murase
Summary: To assess the inorganic carbon cycle in the eastern Indian sector of the Southern Ocean, various parameters were measured during the KY18 survey. It was found that the ocean in this region acts as a weak CO2 sink, with the CO2 flux being influenced by biological activity and temperature. The study also showed an increase in oceanic and atmospheric CO2 concentrations over time, primarily driven by the rise in atmospheric CO2 and changes in water-mass distribution.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Oceanography
Matthis Auger, Jean-Baptiste Sallee, Pierre Prandi, Alberto C. Naveira Garabato
Summary: A novel multi-satellite product is used to study the seasonal cycle of sea surface height and geostrophic circulation in the subpolar Southern Ocean. Three main modes of variability are identified, all primarily driven by wind forcing. The first mode is associated with the seasonal variation of the subpolar gyres, consistent with Sverdrup dynamics. The second mode is related to the Antarctic Slope Current, showing a rapid circumpolar propagation along the continental slope consistent with the Southern Mode. The third mode appears to be driven by sea ice-modulated surface stress and leads to an offshore extension of the Antarctic Slope Current.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Meteorology & Atmospheric Sciences
Elizabeth Ellison, Laura Cimoli, Ali Mashayek
Summary: Oceanic cross-density mixing is crucial for maintaining ocean density stratification and meridional overturning circulation. Changes in mixing in the Southern Ocean can cause significant alterations to biogeochemical tracer distributions, impacting both short and long-term scales.
Review
Multidisciplinary Sciences
Sandy J. Thomalla, Marcel Du Plessis, Nicolas Fauchereau, Isabelle Giddy, Luke Gregor, Stephanie Henson, Warren R. Joubert, Hazel Little, Pedro M. S. Monteiro, Thato Mtshali, Sarah Nicholson, Thomas J. Ryan-Keogh, Sebastiaan Swart
Summary: This review article summarizes relevant research that highlights the important role of fine-scale dynamics in connecting physical forcing mechanisms to biogeochemical responses. It emphasizes the potential for integrating autonomous and remote sensing observations of fine scale dynamics to derive regionally optimized biogeochemical parameterizations for Southern Ocean models. Ongoing development in both the observational and modeling fields will generate new insights for improved predictions of the sensitivity of the Southern Ocean BCP to climate change.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Geosciences, Multidisciplinary
Cole F. Persch, Pedro Dinezio, Nicole S. Lovenduski
Summary: The study reveals the correlation between orbital precession and CO2 outgassing in the Southern Ocean. During periods of high precession, there is an anomalous release of CO2 from the Southern Ocean, which can be attributed to the poleward shift in the southern westerly winds, enhanced Southern Ocean meridional overturning, and an increase in the surface ocean partial pressure of CO2 along the core of the Antarctic Circumpolar Current.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Meteorology & Atmospheric Sciences
Takamitsu Ito
Summary: This study develops a new regional model of the Southern Ocean that accurately simulates the partial pressure of carbon dioxide and net primary production. The model performs well on seasonal to interannual timescales and is validated against observational data.
JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS
(2022)
Article
Multidisciplinary Sciences
J. B. Sallee, E. P. Abrahamsen, C. Allaigre, M. Auger, H. Ayres, R. Badhe, J. Boutin, J. A. Brearley, C. de Lavergne, A. M. M. ten Doeschate, E. S. Droste, M. D. du Plessis, D. Ferreira, I. S. Giddy, B. Guelk, N. Gruber, M. Hague, M. Hoppema, S. A. Josey, T. Kanzow, M. Kimmritz, M. R. Lindeman, P. J. Llanillo, N. S. Lucas, G. Madec, D. P. Marshall, A. J. S. Meijers, M. P. Meredith, M. Mohrmann, P. M. S. Monteiro, C. Mosneron Dupin, K. Naeck, A. Narayanan, A. C. Naveira Garabato, S-a. Nicholson, A. Novellino, M. oedalen, S. osterhus, W. Park, R. D. Patmore, E. Piedagnel, F. Roquet, H. S. Rosenthal, T. Roy, R. Saurabh, Y. Silvy, T. Spira, N. Steiger, A. F. Styles, S. Swart, L. Vogt, B. Ward, S. Zhou
Summary: The Southern Ocean plays a crucial role in regulating the global climate by controlling heat and carbon exchanges between the atmosphere and the ocean. However, there is limited knowledge about the oceanic processes in this extreme environment due to a lack of observations and the difficulty of capturing intermittent processes in current Earth system models. The Southern Ocean Carbon and Heat Impact on Climate programme aims to address this knowledge gap by studying the physical processes controlling exchanges between the atmosphere, ocean, and sea ice through a combination of observational and modeling approaches.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Environmental Sciences
R. M. Wright, C. Le Quere, N. Mayot, A. Olsen, D. C. E. Bakker
Summary: The Southern Ocean is crucial for carbon uptake, transport, and storage by the global oceans. It is the largest CO2 sink but has low storage of anthropogenic carbon due to the unique combination of upwelling of deep waters and northward transport of surface carbon driven by high winds. Through modeling and observations, we isolate the direct effect of increasing anthropogenic CO2 from the indirect effect of climate variability and change on carbon reorganization in the Southern Ocean. Climate variability and change have a significant impact on carbon storage in the Southern Ocean, comparable to the effect of anthropogenic CO2.
GLOBAL BIOGEOCHEMICAL CYCLES
(2023)
Article
Meteorology & Atmospheric Sciences
Jia-Jia Chen, Neil C. Swart, Xuhua Cheng
Summary: Since the 1950s, the Southern Ocean has been warming in the south and cooling in the north. The exact drivers of these opposing latitudinal patterns of change were not well understood. However, analysis of atmosphere-ocean general circulation models shows that subsurface cooling in the north is a result of a combination of weak warming from greenhouse gases and cooling forced by aerosols.
JOURNAL OF CLIMATE
(2022)
Article
Environmental Sciences
Tim Devries, Kana Yamamoto, Rik Wanninkhof, Nicolas Gruber, Judith Hauck, Jens Daniel Mueller, Laurent Bopp, Dustin Carroll, Brendan Carter, Thi-Tuyet-Trang Chau, Scott C. Doney, Marion Gehlen, Lucas Gloege, Luke Gregor, Stephanie Henson, Ji Hyun Kim, Yosuke Iida, Tatiana Ilyina, Peter Landschuetzer, Corinne Le Quere, David Munro, Cara Nissen, Lavinia Patara, Fiz F. Perez, Laure Resplandy, Keith B. Rodgers, Joerg Schwinger, Roland Seferian, Valentina Sicardi, Jens Terhaar, Joaquin Trinanes, Hiroyuki Tsujino, Andrew Watson, Sayaka Yasunaka, Jiye Zeng
Summary: This contribution analyzes the processes that determine the global ocean carbon sink and its trends and variability over the period 1985-2018 using models and observation-based products. The study finds that anthropogenic CO2 dominates the ocean CO2 sink, while climate-driven variability is potentially large but highly uncertain.
GLOBAL BIOGEOCHEMICAL CYCLES
(2023)
Article
Multidisciplinary Sciences
Jeongmin Yun, Sujong Jeong, Nicolas Gruber, Luke Gregor, Chang-Hoi Ho, Shilong Piao, Philippe Ciais, David Schimel, Eun Young Kwon
Summary: The seasonal amplitude of atmospheric CO2 is increasing globally, with strong positive trends observed in the southern high latitudes after 2000. This increase is largely attributed to the increasing seasonality of air-sea CO2 exchange over the Southern Ocean around 2000.
Article
Geosciences, Multidisciplinary
Jinlong Du, Ying Ye, Xu Zhang, Christoph Voelker, Jun Tian
Summary: The mechanisms accounting for atmospheric pCO(2) drawdown during glacial periods have been proposed to be critical, particularly those operating in the North Atlantic (NA) and Southern Ocean (SO). This study conducted simulations to examine their effects during idealized glacial stages, revealing that cooling in the SO can trigger an initial pCO(2) drawdown, while further cooling in the NA enhances ocean carbon uptake and the SO-induced stronger deep stratification prevents carbon exchange between deep and upper ocean.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Biodiversity Conservation
Juliano Palacios-Abrantes, Thomas L. Frolicher, Gabriel Reygondeau, U. Rashid Sumaila, Alessandro Tagliabue, Colette C. C. Wabnitz, William W. L. Cheung
Summary: Climate change is causing shifts in the distribution of shared fish stocks between neighboring countries, affecting international fisheries governance. By 2030, 23% of transboundary stocks will have shifted, and by the end of the century, projections show that 45% of stocks globally will have shifted. Countries highly dependent on fisheries will be hotspots for these shifts.
GLOBAL CHANGE BIOLOGY
(2022)
Article
Environmental Sciences
Anh Le-Duy Pham, Olivier Aumont, Lavenia Ratnarajah, Alessandro Tagliabue
Summary: Marine free-living bacteria play a crucial role in the cycling of essential biogeochemical elements, and their growth is regulated by nutrient availability, particularly iron. Understanding the factors limiting bacterial growth and their role in the iron cycle is important for understanding biogeochemical cycling.
GLOBAL BIOGEOCHEMICAL CYCLES
(2022)
Article
Oceanography
M. D. du Plessis, S. Swart, L. C. Biddle, I. S. Giddy, P. M. S. Monteiro, C. J. C. Reason, A. F. Thompson, S-A Nicholson
Summary: This study investigates the impact of buoyancy forcing and wind-driven processes on mixed layer thermohaline variability in three Southern Ocean regions. The results show that heat flux is the main driver of buoyancy gain, and shallow mixed layers and strong stratification enhance buoyancy gain in certain regions. The study also reveals the importance of surface forcing occurring between 1 and 10 days on water mass transformation in the Southern Ocean.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Oceanography
Estel Font, Bastien Y. Queste, Sebastiaan Swart
Summary: The study uses high-resolution underwater glider data and reanalysis data sets to describe the spatial and temporal variability of the mixed layer in the Gulf of Oman during winter and spring. It evaluates the effects of surface forcing and submesoscale processes on upper ocean buoyancy and mixed layer stratification, highlighting the impact of wind events on intraseasonal deepening and restratification of the mixed layer.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Geosciences, Multidisciplinary
Johan M. Edholm, Sebastiaan Swart, Marcel D. Plessis, Sarah-Anne Nicholson
Summary: This study explores the impact of atmospheric rivers (ARs) on surface ocean buoyancy using high-resolution surface observations. It finds that when ARs combine with storms, precipitation is significantly enhanced, and the accumulated precipitation from ARs provides a buoyancy gain to the surface ocean equivalent to surface heat fluxes. The study also highlights that ARs play an important role in summer precipitation over the subpolar Southern Ocean and can alter the upper-ocean buoyancy budget across different timescales.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Fisheries
M. F. Cronin, S. Swart, C. A. Marandino, C. Anderson, P. Browne, S. Chen, W. R. Joubert, U. Schuster, R. Venkatesan, C. Addey, O. Alves, F. Ardhuin, S. Battle, M. A. Bourassa, Z. Chen, M. Chory, C. Clayson, R. B. de Souza, M. du Plessis, M. Edmondson, J. B. Edson, S. T. Gille, J. Hermes, V Hormann, S. A. Josey, M. Kurz, T. Lee, F. Maicu, E. H. Moustahfid, S-A Nicholson, E. S. Nyadjro, J. Palter, R. G. Patterson, S. G. Penny, L. P. Pezzi, N. Pinardi, J. E. J. Reeves Eyre, N. Rome, A. C. Subramanian, C. Stienbarger, T. Steinhoff, A. J. Sutton, H. Tomita, S. M. Wills, C. Wilson, L. Yu
Summary: The Observing Air-Sea Interactions Strategy (OASIS) is a program that aims to improve Earth system forecasts, CO2 uptake assessments, and provide ocean information for decision makers. It focuses on creating a global network of mobile air-sea observing platforms, a satellite network optimized for measuring air-sea fluxes, and improving the representation of air-sea coupling in Earth system models. The program consists of various activities such as network design, model improvement, partnership building, and best practices experiments.
ICES JOURNAL OF MARINE SCIENCE
(2023)
Article
Geosciences, Multidisciplinary
P. N. Sedwick, B. M. Sohst, K. N. Buck, S. Caprara, R. J. Johnson, D. C. Ohnemus, L. E. Sofen, A. Tagliabue, B. S. Twining, T. E. Williams
Summary: Constraining the role of dust deposition in regulating the concentration of iron in surface ocean waters requires understanding the flux of seawater-soluble iron in aerosols and the replacement time of dissolved iron in the euphotic zone. This study estimates these quantities using DFe data from the Bermuda Atlantic Time-series Study region and measurements of iron in aerosols and rain from Bermuda in 2019. The results suggest a seasonal variation in surface DFe concentrations and a mean euphotic-zone residence time of 0.8-1.9 years for DFe with respect to aeolian input.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Oceanography
I. S. Giddy, I. Fer, S. Swart, S. A. Nicholson
Summary: In this study, the seasonal warming of Antarctic Winter Water (WW) is investigated using glider measurements. It is found that the dissipation rates in the surface layer are mainly forced by winds, while mixing to the base of the mixed layer during strong wind events is suppressed by vertical stratification from sea ice melt. In addition, a subsurface layer of enhanced dissipation is maintained by double-diffusive convection (DDC) between the WW layer and the warm and saline circumpolar deep water. The study highlights the importance of adequately representing DDC in ocean models, as excluding it underestimates the warming of WW by 23%.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2023)
Review
Multidisciplinary Sciences
Sebastiaan Swart, Marcel D. D. du Plessis, Sarah-Anne Nicholson, Pedro M. S. Monteiro, Lilian A. A. Dove, Sandy Thomalla, Andrew F. F. Thompson, Louise C. C. Biddle, Johan M. M. Edholm, Isabelle Giddy, Karen J. J. Heywood, Craig Lee, Amala Mahadevan, Geoff Shilling, Ronald Buss de Souza
Summary: Interactions between the upper ocean and air-ice-ocean fluxes in the Southern Ocean have a crucial impact on global climate through their influence on circulation patterns and heat and carbon uptake. However, limited observational coverage and challenges in collecting accurate data at the right time and location have hindered progress in understanding the complex ocean-atmosphere system. Recent advances in observing fine-scale ocean processes using autonomous platforms have provided valuable insights into the Southern Ocean's mixed layer and its variability. This article reviews these advancements, as well as the ongoing efforts to study the connections between the ocean, atmosphere, and cryosphere.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Multidisciplinary Sciences
Thomas J. Ryan-Keogh, Sandy J. Thomalla, Pedro M. S. Monteiro, Alessandro Tagliabue
Summary: Southern Ocean primary productivity is affected by light and iron limitation, but the factors determining iron availability, accessibility, and demand are uncertain. In this study, we analyzed long-term data collected by Biogeochemical Argo floats and ship-based platforms to examine the effects of iron stress on phytoplankton photophysiology. We observed a significant multidecadal trend of increasing iron stress and declining regional net primary production. This trend is attributed to changes in the Southern Ocean mixed-layer physics and complex biological and chemical feedback, highlighting important ongoing changes in the Southern Ocean carbon cycle.
Article
Geosciences, Multidisciplinary
I. S. Giddy, S. -A Nicholson, B. Y. Queste, S. Thomalla, S. Swart
Summary: This study reveals that increased sea-ice formation over winter leads to more intense phytoplankton blooms and higher carbon export in the Northeast Weddell Sea the following summer. However, carbon export beyond the winter mixed layer is not directly proportional to primary production, suggesting different mechanisms at play. The spatial variability in the response of phytoplankton blooms to sea-ice volume highlights the need to consider spatial heterogeneity in the biological carbon pump's response to future sea-ice changes.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Biodiversity Conservation
Alessandro Tagliabue, Benjamin S. Twining, Nicolas Barrier, Olivier Maury, Manon Berger, Laurent Bopp
Summary: Climate change scenarios indicate the need for large-scale carbon dioxide removal to combat global warming, putting the focus back on ocean iron fertilization (OIF). However, our study shows that while OIF can increase carbon sequestration, it may also intensify the decline of tropical ocean productivity and ecosystem biomass, with limited impact on atmospheric CO2. The interaction between OIF and ongoing climate change could lead to reduced animal biomass in tropical regions, particularly in coastal exclusive economic zones (EEZs), which could have implications for fisheries.
GLOBAL CHANGE BIOLOGY
(2023)
Article
Multidisciplinary Sciences
Alessandro Tagliabue, Kristen N. N. Buck, Laura E. E. Sofen, Benjamin S. S. Twining, Olivier Aumont, Philip W. W. Boyd, Salvatore Caprara, William B. B. Homoky, Rod Johnson, Daniela Konig, Daniel C. C. Ohnemus, Bettina Sohst, Peter Sedwick
Summary: Iron is important in regulating the ocean carbon cycle, with organic ligands playing a crucial role in stabilizing dissolved iron concentrations. However, the role of authigenic iron phases and the inconsistencies observed in dissolved iron cycling challenge the primary control of ligands. Through a study in the Bermuda Atlantic Time-series Study (BATS) region, it was found that upper-ocean dissolved iron dynamics are decoupled from ligands, indicating the need for a mechanism that allows dissolved iron to escape ligand stabilization and form a reservoir of settling iron particles. When this mechanism was implemented in a global-scale biogeochemical model, it successfully reproduced seasonal iron-cycle dynamics and global datasets where previous models failed.
Article
Ecology
Garrett Sharpe, Liang Zhao, Meredith G. Meyer, Weida Gong, Shannon M. Burns, Allesandro Tagliabue, Kristen N. Buck, Alyson E. Santoro, Jason R. Graff, Adrian Marchetti, Scott Gifford
Summary: Synechococcus, the most abundant cyanobacteria in high latitude regions, plays a significant role in annual marine net primary productivity. However, the uneven sampling of Synechococcus populations across the ocean, particularly in high-latitude, High Nutrient Low Chlorophyll (HNLC) regions, has limited our understanding of their adaptations to iron limitation and their influence on carbon, nitrogen, and iron cycles. This study focuses on Synechococcus populations in the subarctic North Pacific, a well-characterized HNLC region, and reveals their dependence on ammonium and other forms of recycled nitrogen, leading to reduced iron requirements. The findings have important implications for modeling the contribution of cyanobacteria to primary production and carbon export.
ISME COMMUNICATIONS
(2023)
Article
Ecology
Natasha Rene van Horsten, Helene Planquette, Geraldine Sarthou, Thomas James Ryan-Keogh, Nolwenn Lemaitre, Thato Nicholas Mtshali, Alakendra Roychoudhury, Eva Bucciarelli
Summary: The Southern Ocean is globally important in the carbon cycle, and the mesopelagic remineralisation processes likely have a longer timescale than previously thought, leading to higher carbon export efficiency in the southern region.
