Articles | Volume 19, issue 3
https://doi.org/10.5194/bg-19-907-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-19-907-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
14 Feb 2022
Research article |
| 14 Feb 2022
| 14 Feb 2022
Evaluating the Arabian Sea as a regional source of atmospheric CO2: seasonal variability and drivers
Center for Prototype Climate Modeling, New York University Abu Dhabi, Abu Dhabi, UAE
Arabian Center for Climate and Environmental Sciences, New York University Abu Dhabi, Abu Dhabi, UAE
Zouhair Lachkar
Center for Prototype Climate Modeling, New York University Abu Dhabi, Abu Dhabi, UAE
Arabian Center for Climate and Environmental Sciences, New York University Abu Dhabi, Abu Dhabi, UAE
Shafer Smith
Courant Institute of Mathematical Sciences, New York University, New York, USA
Arabian Center for Climate and Environmental Sciences, New York University Abu Dhabi, Abu Dhabi, UAE
Marina Lévy
Sorbonne Université (CNRS/IRD/MNHN), LOCEAN-IPSL, Paris, France
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Biogeosciences, 15, 7485–7504, https://doi.org/10.5194/bg-15-7485-2018, https://doi.org/10.5194/bg-15-7485-2018, 2018
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The OUTPACE cruise took place between New Caledonia and French Polynesia. The main purpose was to understand how micro-organisms can survive in a very poor environment. One main source of nutrients is at depth, below the euphotic layer where micro-organisms live. The purpose of the turbulence measurements was to determine to which extent turbulence may
upliftnutrients into the euphotic layer. The origin of the turbulence that was found contrasted along the transect was also determined.
Thierry Moutin, Thibaut Wagener, Mathieu Caffin, Alain Fumenia, Audrey Gimenez, Melika Baklouti, Pascale Bouruet-Aubertot, Mireille Pujo-Pay, Karine Leblanc, Dominique Lefevre, Sandra Helias Nunige, Nathalie Leblond, Olivier Grosso, and Alain de Verneil
Biogeosciences, 15, 2961–2989, https://doi.org/10.5194/bg-15-2961-2018, https://doi.org/10.5194/bg-15-2961-2018, 2018
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Surface waters of the western tropical South Pacific were sampled along a longitudinal 4000 km transect during the stratified period between the Melanesian Archipelago and the western part of the South Pacific gyre. We found a significant biological carbon pump sustained almost exclusively by N2 fixation and essentially controlled by phosphate availability in the iron-rich Melanesian Archipelago waters which appears to be a net sink for atmospheric CO2 while the gyre is in a quasi-steady state.
Mathieu Caffin, Thierry Moutin, Rachel Ann Foster, Pascale Bouruet-Aubertot, Andrea Michelangelo Doglioli, Hugo Berthelot, Cécile Guieu, Olivier Grosso, Sandra Helias-Nunige, Nathalie Leblond, Audrey Gimenez, Anne Alexandra Petrenko, Alain de Verneil, and Sophie Bonnet
Biogeosciences, 15, 2565–2585, https://doi.org/10.5194/bg-15-2565-2018, https://doi.org/10.5194/bg-15-2565-2018, 2018
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We performed N budgets to assess the role of N2 fixation on production and export in the western tropical South Pacific Ocean. We deployed a combination of techniques including high-sensitivity measurements of N input and sediment traps deployment. We demonstrated that N2 fixation was the major source of new N before atmospheric deposition and upward nitrate fluxes. It contributed significantly to organic matter export, indicating a high efficiency of this region to export carbon.
Louise Rousselet, Alain de Verneil, Andrea M. Doglioli, Anne A. Petrenko, Solange Duhamel, Christophe Maes, and Bruno Blanke
Biogeosciences, 15, 2411–2431, https://doi.org/10.5194/bg-15-2411-2018, https://doi.org/10.5194/bg-15-2411-2018, 2018
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The patterns of the large- and fine-scale surface circulation on biogeochemical and biological distributions are examined in the western tropical South Pacific (WTSP) in the context of the OUTPACE oceanographic cruise. The combined use of in situ and satellite data allows for the identification of water mass transport pathways and fine-scale structures, such as fronts, that drive surface distribution of tracers and microbial community structures.
Alain de Verneil, Louise Rousselet, Andrea M. Doglioli, Anne A. Petrenko, Christophe Maes, Pascale Bouruet-Aubertot, and Thierry Moutin
Biogeosciences, 15, 2125–2147, https://doi.org/10.5194/bg-15-2125-2018, https://doi.org/10.5194/bg-15-2125-2018, 2018
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Oceanographic campaigns to measure biogeochemical processes popularly deploy drifters with onboard incubations to stay in a single body of water. Here, we aggregate physical data taken during such a cruise, OUTPACE, to independently test in a new approach whether the drifter really stayed in what can be considered a single biological or chemical environment. This study concludes that future campaigns would benefit from similar data collection and analysis to validate their sampling strategy.
Alain de Verneil, Louise Rousselet, Andrea M. Doglioli, Anne A. Petrenko, and Thierry Moutin
Biogeosciences, 14, 3471–3486, https://doi.org/10.5194/bg-14-3471-2017, https://doi.org/10.5194/bg-14-3471-2017, 2017
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A surface summer plankton bloom in the western tropical South Pacific was sampled during the Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) cruise. We characterize the bloom's properties and the circulation responsible for its evolution. Nitrogen fixation helped sustain the bloom, and larger-scale flows, rather than the smaller ones, explain its movements. Future studies of blooms in this region can make use of these findings to track the horizontal export of plankton production.
Thierry Moutin, Andrea Michelangelo Doglioli, Alain de Verneil, and Sophie Bonnet
Biogeosciences, 14, 3207–3220, https://doi.org/10.5194/bg-14-3207-2017, https://doi.org/10.5194/bg-14-3207-2017, 2017
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The overall goal of OUTPACE was to obtain a successful representation of the interactions between planktonic organisms and the cycle of biogenic elements in the western tropical South Pacific Ocean across trophic and N2 fixation gradients. The international OUTPACE cruise took place between 18 February and 3 April 2015 aboard the RV L’Atalante and involved 60 scientists. The transect covered ~4 000 km from the western part of the Melanesian archipelago to the western boundary of the gyre.
Madhavan Girijakumari Keerthi, Olivier Aumont, Lester Kwiatkowski, and Marina Levy
EGUsphere, https://doi.org/10.5194/egusphere-2024-2294, https://doi.org/10.5194/egusphere-2024-2294, 2024
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Our study assesses the capability of CMIP6 models to reproduce satellite observations of sub-seasonal chlorophyll variability. Models struggle to reproduce the sub-seasonal variance and its contribution across timescales. Some models overestimate sub-seasonal variance and exaggerate its role in annual fluctuations, while others underestimate it. Underestimation is likely due to the coarse resolution of models, while overestimation may result from intrinsic oscillations in biogeochemical models.
Stéphane Doléac, Marina Lévy, Roy El Hourany, and Laurent Bopp
EGUsphere, https://doi.org/10.5194/egusphere-2024-1820, https://doi.org/10.5194/egusphere-2024-1820, 2024
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Phytoplankton net primary production (NPP) is influenced by many processes, and their representation varies across Earth-system models. This leads to differing projections for NPP's future under climate change, especially in the North Atlantic. To address this, we identified and assessed the processes controlling NPP in each model. This assessment helped us select the most reliable models, significantly improving NPP projections in the region.
Roy El Hourany, Juan Pierella Karlusich, Lucie Zinger, Hubert Loisel, Marina Levy, and Chris Bowler
Ocean Sci., 20, 217–239, https://doi.org/10.5194/os-20-217-2024, https://doi.org/10.5194/os-20-217-2024, 2024
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Satellite observations offer valuable information on phytoplankton abundance and community structure. Here, we employ satellite observations to infer seven phytoplankton groups at a global scale based on a new molecular method from Tara Oceans. The link has been established using machine learning approaches. The output of this work provides excellent tools to collect essential biodiversity variables and a foundation to monitor the evolution of marine biodiversity.
Inès Mangolte, Marina Lévy, Clément Haëck, and Mark D. Ohman
Biogeosciences, 20, 3273–3299, https://doi.org/10.5194/bg-20-3273-2023, https://doi.org/10.5194/bg-20-3273-2023, 2023
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Ocean fronts are ecological hotspots, associated with higher diversity and biomass for many marine organisms, from bacteria to whales. Using in situ data from the California Current Ecosystem, we show that far from being limited to the production of diatom blooms, fronts are the scene of complex biophysical couplings between biotic interactions (growth, competition, and predation) and transport by currents that generate planktonic communities with an original taxonomic and spatial structure.
Saeed Hariri, Sabrina Speich, Bruno Blanke, and Marina Lévy
Ocean Sci., 19, 1183–1201, https://doi.org/10.5194/os-19-1183-2023, https://doi.org/10.5194/os-19-1183-2023, 2023
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This work presents a series of studies conducted by the authors on the application of the Lagrangian approach for the connectivity analysis between different ocean locations in an idealized open-ocean model. We assess how the connectivity properties of typical oceanic flows are affected by the fine-scale circulation and discuss the challenges facing ocean connectivity estimates related to the spatial resolution. Our results are important to improve the understanding of marine ecosystems.
Clément Haëck, Marina Lévy, Inès Mangolte, and Laurent Bopp
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Damien Couespel, Marina Lévy, and Laurent Bopp
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An alarming consequence of climate change is the oceanic primary production decline projected by Earth system models. These coarse-resolution models parameterize oceanic eddies. Here, idealized simulations of global warming with increasing resolution show that the decline in primary production in the eddy-resolved simulations is half as large as in the eddy-parameterized simulations. This stems from the high sensitivity of the subsurface nutrient transport to model resolution.
Clément Bricaud, Julien Le Sommer, Gurvan Madec, Christophe Calone, Julie Deshayes, Christian Ethe, Jérôme Chanut, and Marina Levy
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In order to reduce the cost of ocean biogeochemical models, a multi-grid approach where ocean dynamics and tracer transport are computed with different spatial resolution has been developed in the NEMO v3.6 OGCM. Different experiments confirm that the spatial resolution of hydrodynamical fields can be coarsened without significantly affecting the resolved passive tracer fields. This approach leads to a factor of 7 reduction of the overhead associated with running a full biogeochemical model.
Pascale Bouruet-Aubertot, Yannis Cuypers, Andrea Doglioli, Mathieu Caffin, Christophe Yohia, Alain de Verneil, Anne Petrenko, Dominique Lefèvre, Hervé Le Goff, Gilles Rougier, Marc Picheral, and Thierry Moutin
Biogeosciences, 15, 7485–7504, https://doi.org/10.5194/bg-15-7485-2018, https://doi.org/10.5194/bg-15-7485-2018, 2018
Short summary
Short summary
The OUTPACE cruise took place between New Caledonia and French Polynesia. The main purpose was to understand how micro-organisms can survive in a very poor environment. One main source of nutrients is at depth, below the euphotic layer where micro-organisms live. The purpose of the turbulence measurements was to determine to which extent turbulence may
upliftnutrients into the euphotic layer. The origin of the turbulence that was found contrasted along the transect was also determined.
Thierry Moutin, Thibaut Wagener, Mathieu Caffin, Alain Fumenia, Audrey Gimenez, Melika Baklouti, Pascale Bouruet-Aubertot, Mireille Pujo-Pay, Karine Leblanc, Dominique Lefevre, Sandra Helias Nunige, Nathalie Leblond, Olivier Grosso, and Alain de Verneil
Biogeosciences, 15, 2961–2989, https://doi.org/10.5194/bg-15-2961-2018, https://doi.org/10.5194/bg-15-2961-2018, 2018
Short summary
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Surface waters of the western tropical South Pacific were sampled along a longitudinal 4000 km transect during the stratified period between the Melanesian Archipelago and the western part of the South Pacific gyre. We found a significant biological carbon pump sustained almost exclusively by N2 fixation and essentially controlled by phosphate availability in the iron-rich Melanesian Archipelago waters which appears to be a net sink for atmospheric CO2 while the gyre is in a quasi-steady state.
Mathieu Caffin, Thierry Moutin, Rachel Ann Foster, Pascale Bouruet-Aubertot, Andrea Michelangelo Doglioli, Hugo Berthelot, Cécile Guieu, Olivier Grosso, Sandra Helias-Nunige, Nathalie Leblond, Audrey Gimenez, Anne Alexandra Petrenko, Alain de Verneil, and Sophie Bonnet
Biogeosciences, 15, 2565–2585, https://doi.org/10.5194/bg-15-2565-2018, https://doi.org/10.5194/bg-15-2565-2018, 2018
Short summary
Short summary
We performed N budgets to assess the role of N2 fixation on production and export in the western tropical South Pacific Ocean. We deployed a combination of techniques including high-sensitivity measurements of N input and sediment traps deployment. We demonstrated that N2 fixation was the major source of new N before atmospheric deposition and upward nitrate fluxes. It contributed significantly to organic matter export, indicating a high efficiency of this region to export carbon.
Louise Rousselet, Alain de Verneil, Andrea M. Doglioli, Anne A. Petrenko, Solange Duhamel, Christophe Maes, and Bruno Blanke
Biogeosciences, 15, 2411–2431, https://doi.org/10.5194/bg-15-2411-2018, https://doi.org/10.5194/bg-15-2411-2018, 2018
Short summary
Short summary
The patterns of the large- and fine-scale surface circulation on biogeochemical and biological distributions are examined in the western tropical South Pacific (WTSP) in the context of the OUTPACE oceanographic cruise. The combined use of in situ and satellite data allows for the identification of water mass transport pathways and fine-scale structures, such as fronts, that drive surface distribution of tracers and microbial community structures.
Alain de Verneil, Louise Rousselet, Andrea M. Doglioli, Anne A. Petrenko, Christophe Maes, Pascale Bouruet-Aubertot, and Thierry Moutin
Biogeosciences, 15, 2125–2147, https://doi.org/10.5194/bg-15-2125-2018, https://doi.org/10.5194/bg-15-2125-2018, 2018
Short summary
Short summary
Oceanographic campaigns to measure biogeochemical processes popularly deploy drifters with onboard incubations to stay in a single body of water. Here, we aggregate physical data taken during such a cruise, OUTPACE, to independently test in a new approach whether the drifter really stayed in what can be considered a single biological or chemical environment. This study concludes that future campaigns would benefit from similar data collection and analysis to validate their sampling strategy.
Zouhair Lachkar, Marina Lévy, and Shafer Smith
Biogeosciences, 15, 159–186, https://doi.org/10.5194/bg-15-159-2018, https://doi.org/10.5194/bg-15-159-2018, 2018
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This study provides a new contribution to our understanding of the coupling between the oxygen minimum zones (OMZs) and climate. It explores how idealized changes in summer and winter Indian monsoon winds affect the productivity of the Arabian Sea and the size and intensity of its OMZ. We find that intensification of Indian monsoon winds can amplify climate warming on decadal to centennial timescales.
Madhavan Girijakumari Keerthi, Matthieu Lengaigne, Marina Levy, Jerome Vialard, Vallivattathillam Parvathi, Clément de Boyer Montégut, Christian Ethé, Olivier Aumont, Iyyappan Suresh, Valiya Parambil Akhil, and Pillathu Moolayil Muraleedharan
Biogeosciences, 14, 3615–3632, https://doi.org/10.5194/bg-14-3615-2017, https://doi.org/10.5194/bg-14-3615-2017, 2017
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The northern Arabian Sea hosts a winter chlorophyll bloom, which exhibits strong interannual variability. The processes responsible for this interannual variation of the bloom are investigated using observations and a model. The interannual fluctuations of the winter bloom are largely related to the interannual mixed-layer depth (MLD) anomalies, which are driven by net heat flux anomalies. MLD controls the bloom amplitude through a modulation of nutrient turbulent fluxes into the mixed layer.
Alain de Verneil, Louise Rousselet, Andrea M. Doglioli, Anne A. Petrenko, and Thierry Moutin
Biogeosciences, 14, 3471–3486, https://doi.org/10.5194/bg-14-3471-2017, https://doi.org/10.5194/bg-14-3471-2017, 2017
Short summary
Short summary
A surface summer plankton bloom in the western tropical South Pacific was sampled during the Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) cruise. We characterize the bloom's properties and the circulation responsible for its evolution. Nitrogen fixation helped sustain the bloom, and larger-scale flows, rather than the smaller ones, explain its movements. Future studies of blooms in this region can make use of these findings to track the horizontal export of plankton production.
Thierry Moutin, Andrea Michelangelo Doglioli, Alain de Verneil, and Sophie Bonnet
Biogeosciences, 14, 3207–3220, https://doi.org/10.5194/bg-14-3207-2017, https://doi.org/10.5194/bg-14-3207-2017, 2017
Short summary
Short summary
The overall goal of OUTPACE was to obtain a successful representation of the interactions between planktonic organisms and the cycle of biogenic elements in the western tropical South Pacific Ocean across trophic and N2 fixation gradients. The international OUTPACE cruise took place between 18 February and 3 April 2015 aboard the RV L’Atalante and involved 60 scientists. The transect covered ~4 000 km from the western part of the Melanesian archipelago to the western boundary of the gyre.
Parvathi Vallivattathillam, Suresh Iyyappan, Matthieu Lengaigne, Christian Ethé, Jérôme Vialard, Marina Levy, Neetu Suresh, Olivier Aumont, Laure Resplandy, Hema Naik, and Wajih Naqvi
Biogeosciences, 14, 1541–1559, https://doi.org/10.5194/bg-14-1541-2017, https://doi.org/10.5194/bg-14-1541-2017, 2017
Short summary
Short summary
During late boreal summer and fall, the west coast of India (WCI) experiences hypoxia, which turns into anoxia during some years. We analyze a coupled physical–biogeochemical simulation over the 1960–2012 period to investigate the physical processes influencing oxycline interannual variability off the WCI. We show that fall WCI oxycline fluctuations are strongly related to Indian Ocean Dipole (IOD), with positive IODs preventing anoxia, while negative IODs do not necessarily result in anoxia.
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Dimethyl sulfide (DMS) climatologies, fluxes, and trends – Part 2: Sea–air fluxes
High-frequency continuous measurements reveal strong diel and seasonal cycling of pCO2 and CO2 flux in a mesohaline reach of the Chesapeake Bay
Significant role of physical transport in the marine carbon monoxide (CO) cycle: observations in the East Sea (Sea of Japan), the western North Pacific, and the Bering Sea in summer
Central Arctic Ocean surface–atmosphere exchange of CO2 and CH4 constrained by direct measurements
Spatial and seasonal variability in volatile organic sulfur compounds in seawater and the overlying atmosphere of the Bohai and Yellow seas
Estimating marine carbon uptake in the northeast Pacific using a neural network approach
Sea–air methane flux estimates derived from marine surface observations and instantaneous atmospheric measurements in the northern Labrador Sea and Baffin Bay
Global analysis of the controls on seawater dimethylsulfide spatial variability
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Concentrations of dissolved dimethyl sulfide (DMS), methanethiol and other trace gases in context of microbial communities from the temperate Atlantic to the Arctic Ocean
Marine nitrogen fixation as a possible source of atmospheric water-soluble organic nitrogen aerosols in the subtropical North Pacific
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Tidal mixing of estuarine and coastal waters in the western English Channel is a control on spatial and temporal variability in seawater CO2
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Sea ice concentration impacts dissolved organic gases in the Canadian Arctic
An empirical MLR for estimating surface layer DIC and a comparative assessment to other gap-filling techniques for ocean carbon time series
Derivation of seawater pCO2 from net community production identifies the South Atlantic Ocean as a CO2 source
Eukaryotic community composition in the sea surface microlayer across an east–west transect in the Mediterranean Sea
Enhancement of the North Atlantic CO2 sink by Arctic Waters
Global ocean dimethyl sulfide climatology estimated from observations and an artificial neural network
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Underway seawater and atmospheric measurements of volatile organic compounds in the Southern Ocean
Dimethylsulfide (DMS), marine biogenic aerosols and the ecophysiology of coral reefs
Spatial variations in CO2 fluxes in the Saguenay Fjord (Quebec, Canada) and results of a water mixing model
Gas exchange estimates in the Peruvian upwelling regime biased by multi-day near-surface stratification
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Reviews and syntheses: the GESAMP atmospheric iron deposition model intercomparison study
Increase of dissolved inorganic carbon and decrease in pH in near-surface waters in the Mediterranean Sea during the past two decades
Utilizing the Drake Passage Time-series to understand variability and change in subpolar Southern Ocean pCO2
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Dimethyl sulfide (DMS) is the largest natural source of sulfur in the atmosphere and leads to the formation of cloud condensation nuclei. DMS emission and quantification of its impacts have large uncertainties, but a detailed study on the emissions and drivers of their uncertainty is missing to date. The emissions are usually calculated from the seawater DMS concentrations and a flux parameterization. Here we quantify the differences in DMS seawater products, which can affect DMS fluxes.
Sankirna D. Joge, Anoop S. Mahajan, Shrivardhan Hulswar, Christa A. Marandino, Martí Galí, Thomas G. Bell, Mingxi Yang, and Rafel Simó
Biogeosciences, 21, 4453–4467, https://doi.org/10.5194/bg-21-4453-2024, https://doi.org/10.5194/bg-21-4453-2024, 2024
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Dimethyl sulfide (DMS) is the largest natural source of sulfur in the atmosphere and leads to the formation of cloud condensation nuclei. DMS emissions and quantification of their impacts have large uncertainties, but a detailed study on the range of emissions and drivers of their uncertainty is missing to date. The emissions are calculated from the seawater DMS concentrations and a flux parameterization. Here we quantify the differences in the effect of flux parameterizations used in models.
A. Whitman Miller, Jim R. Muirhead, Amanda C. Reynolds, Mark S. Minton, and Karl J. Klug
Biogeosciences, 21, 3717–3734, https://doi.org/10.5194/bg-21-3717-2024, https://doi.org/10.5194/bg-21-3717-2024, 2024
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High frequency pCO2 measurements reveal net neutral CO2 flux in a mesohaline reach of the Chesapeake Bay. Net off-gassing to the atmosphere begins in June when water temperatures rise above ~26ºC, continuing through November when temperatures fall below ~10ºC. Dissolved CO2 concentrations follow day–night cycles and are especially pronounced in warm waters. From December through May, the river is largely an uninterrupted sink for CO2 (i.e. CO2 is drawn out of the atmosphere into the river).
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Biogeosciences, 21, 1847–1865, https://doi.org/10.5194/bg-21-1847-2024, https://doi.org/10.5194/bg-21-1847-2024, 2024
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Delving into CO dynamics from the East Sea to the Bering Sea, our study unveils the influence of physical transport on CO budgets. By measuring CO concentrations and parameters, we elucidate the interplay between biological and physical processes, highlighting the role of lateral transport in shaping CO distributions. Our findings underscore the importance of considering both biogeochemical and physical drivers in understanding marine carbon fluxes.
John Prytherch, Sonja Murto, Ian Brown, Adam Ulfsbo, Brett F. Thornton, Volker Brüchert, Michael Tjernström, Anna Lunde Hermansson, Amanda T. Nylund, and Lina A. Holthusen
Biogeosciences, 21, 671–688, https://doi.org/10.5194/bg-21-671-2024, https://doi.org/10.5194/bg-21-671-2024, 2024
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We directly measured methane and carbon dioxide exchange between ocean or sea ice and the atmosphere during an icebreaker-based expedition to the central Arctic Ocean (CAO) in summer 2021. These measurements can help constrain climate models and carbon budgets. The methane measurements, the first such made in the CAO, are lower than previous estimates and imply that the CAO is an insignificant contributor to Arctic methane emission. Gas exchange rates are slower than previous estimates.
Juan Yu, Lei Yu, Zhen He, Gui-Peng Yang, Jing-Guang Lai, and Qian Liu
Biogeosciences, 21, 161–176, https://doi.org/10.5194/bg-21-161-2024, https://doi.org/10.5194/bg-21-161-2024, 2024
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The distributions of volatile organic sulfur compounds (VSCs) (DMS, COS, and CS2) in the seawater and atmosphere of the Bohai and Yellow Seas were evaluated. Seasonal variations in VSCs were found and showed summer > spring. The COS concentrations exhibited positive correlation with DOC concentrations in seawater during summer. VSCs concentrations in seawater decreased with the depth. Sea-to-air fluxes of COS, DMS, and CS2 indicated that these marginal seas are sources of atmospheric VSCs.
Patrick J. Duke, Roberta C. Hamme, Debby Ianson, Peter Landschützer, Mohamed M. M. Ahmed, Neil C. Swart, and Paul A. Covert
Biogeosciences, 20, 3919–3941, https://doi.org/10.5194/bg-20-3919-2023, https://doi.org/10.5194/bg-20-3919-2023, 2023
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The ocean is both impacted by climate change and helps mitigate its effects through taking up carbon from the atmosphere. We used a machine learning approach to investigate what controls open-ocean carbon uptake in the northeast Pacific open ocean. Marine heatwaves that lasted 2–3 years increased uptake, while the upwelling strength of the Alaskan Gyre controlled uptake over 10-year time periods. The trend from 1998–2019 suggests carbon uptake in the northeast Pacific open ocean is increasing.
Judith Vogt, David Risk, Evelise Bourlon, Kumiko Azetsu-Scott, Evan N. Edinger, and Owen A. Sherwood
Biogeosciences, 20, 1773–1787, https://doi.org/10.5194/bg-20-1773-2023, https://doi.org/10.5194/bg-20-1773-2023, 2023
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The release of the greenhouse gas methane from Arctic submarine sources could exacerbate climate change in a positive feedback. Continuous monitoring of atmospheric methane levels over a 5100 km voyage in the western margin of the Labrador Sea and Baffin Bay revealed above-global averages likely affected by both onshore and offshore methane sources. Instantaneous sea–air methane fluxes were near zero at all measured stations, including a persistent cold-seep location.
George Manville, Thomas G. Bell, Jane P. Mulcahy, Rafel Simó, Martí Galí, Anoop S. Mahajan, Shrivardhan Hulswar, and Paul R. Halloran
Biogeosciences, 20, 1813–1828, https://doi.org/10.5194/bg-20-1813-2023, https://doi.org/10.5194/bg-20-1813-2023, 2023
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We present the first global investigation of controls on seawater dimethylsulfide (DMS) spatial variability over scales of up to 100 km. Sea surface height anomalies, density, and chlorophyll a help explain almost 80 % of DMS variability. The results suggest that physical and biogeochemical processes play an equally important role in controlling DMS variability. These data provide independent confirmation that existing parameterisations of seawater DMS concentration use appropriate variables.
Ryo Dobashi and David T. Ho
Biogeosciences, 20, 1075–1087, https://doi.org/10.5194/bg-20-1075-2023, https://doi.org/10.5194/bg-20-1075-2023, 2023
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Seagrass meadows are productive ecosystems and bury much carbon. Understanding their role in the global carbon cycle requires knowledge of air–sea CO2 fluxes and hence the knowledge of gas transfer velocity (k). In this study, k was determined from the dual tracer technique in Florida Bay. The observed gas transfer velocity was lower than previous studies in the coastal and open oceans at the same wind speeds, most likely due to wave attenuation by seagrass and limited wind fetch in this area.
Valérie Gros, Bernard Bonsang, Roland Sarda-Estève, Anna Nikolopoulos, Katja Metfies, Matthias Wietz, and Ilka Peeken
Biogeosciences, 20, 851–867, https://doi.org/10.5194/bg-20-851-2023, https://doi.org/10.5194/bg-20-851-2023, 2023
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The oceans are both sources and sinks for trace gases important for atmospheric chemistry and marine ecology. Here, we quantified selected trace gases (including the biological metabolites dissolved dimethyl sulfide, methanethiol and isoprene) along a 2500 km transect from the North Atlantic to the Arctic Ocean. In the context of phytoplankton and bacterial communities, our study suggests that methanethiol (rarely measured before) might substantially influence ocean–atmosphere cycling.
Tsukasa Dobashi, Yuzo Miyazaki, Eri Tachibana, Kazutaka Takahashi, Sachiko Horii, Fuminori Hashihama, Saori Yasui-Tamura, Yoko Iwamoto, Shu-Kuan Wong, and Koji Hamasaki
Biogeosciences, 20, 439–449, https://doi.org/10.5194/bg-20-439-2023, https://doi.org/10.5194/bg-20-439-2023, 2023
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Water-soluble organic nitrogen (WSON) in marine aerosols is important for biogeochemical cycling of bioelements. Our shipboard measurements suggested that reactive nitrogen produced and exuded by nitrogen-fixing microorganisms in surface seawater likely contributed to the formation of WSON aerosols in the subtropical North Pacific. This study provides new implications for the role of marine microbial activity in the formation of WSON aerosols in the ocean surface.
Lukas Eickhoff, Maddalena Bayer-Giraldi, Naama Reicher, Yinon Rudich, and Thomas Koop
Biogeosciences, 20, 1–14, https://doi.org/10.5194/bg-20-1-2023, https://doi.org/10.5194/bg-20-1-2023, 2023
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The formation of ice is an important process in Earth’s atmosphere, biosphere, and cryosphere, in particular in polar regions. Our research focuses on the influence of the sea ice diatom Fragilariopsis cylindrus and of molecules produced by it upon heterogenous ice nucleation. For that purpose, we studied the freezing of tiny droplets containing the diatoms in a microfluidic device. Together with previous studies, our results suggest a common freezing behaviour of various sea ice diatoms.
Lucía Gutiérrez-Loza, Erik Nilsson, Marcus B. Wallin, Erik Sahlée, and Anna Rutgersson
Biogeosciences, 19, 5645–5665, https://doi.org/10.5194/bg-19-5645-2022, https://doi.org/10.5194/bg-19-5645-2022, 2022
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The exchange of CO2 between the ocean and the atmosphere is an essential aspect of the global carbon cycle and is highly relevant for the Earth's climate. In this study, we used 9 years of in situ measurements to evaluate the temporal variability in the air–sea CO2 fluxes in the Baltic Sea. Furthermore, using this long record, we assessed the effect of atmospheric and water-side mechanisms controlling the efficiency of the air–sea CO2 exchange under different wind-speed conditions.
Li Zhou, Dennis Booge, Miming Zhang, and Christa A. Marandino
Biogeosciences, 19, 5021–5040, https://doi.org/10.5194/bg-19-5021-2022, https://doi.org/10.5194/bg-19-5021-2022, 2022
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Trace gas air–sea exchange exerts an important control on air quality and climate, especially in the Southern Ocean (SO). Almost all of the measurements there are skewed to summer, but it is essential to expand our measurement database over greater temporal and spatial scales. Therefore, we report measured concentrations of dimethylsulfide (DMS, as well as related sulfur compounds) and isoprene in the Atlantic sector of the SO. The observations of isoprene are the first in the winter in the SO.
Theresa Barthelmeß and Anja Engel
Biogeosciences, 19, 4965–4992, https://doi.org/10.5194/bg-19-4965-2022, https://doi.org/10.5194/bg-19-4965-2022, 2022
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Greenhouse gases released by human activity cause a global rise in mean temperatures. While scientists can predict how much of these gases accumulate in the atmosphere based on not only human-derived sources but also oceanic sinks, it is rather difficult to predict the major influence of coastal ecosystems. We provide a detailed study on the occurrence, composition, and controls of substances that suppress gas exchange. We thus help to determine what controls coastal greenhouse gas fluxes.
Daniel J. Ford, Gavin H. Tilstone, Jamie D. Shutler, and Vassilis Kitidis
Biogeosciences, 19, 4287–4304, https://doi.org/10.5194/bg-19-4287-2022, https://doi.org/10.5194/bg-19-4287-2022, 2022
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This study explores the seasonal, inter-annual, and multi-year drivers of the South Atlantic air–sea CO2 flux. Our analysis showed seasonal sea surface temperatures dominate in the subtropics, and the subpolar regions correlated with biological processes. Inter-annually, the El Niño–Southern Oscillation correlated with the CO2 flux by modifying sea surface temperatures and biological activity. Long-term trends indicated an important biological contribution to changes in the air–sea CO2 flux.
Laique M. Djeutchouang, Nicolette Chang, Luke Gregor, Marcello Vichi, and Pedro M. S. Monteiro
Biogeosciences, 19, 4171–4195, https://doi.org/10.5194/bg-19-4171-2022, https://doi.org/10.5194/bg-19-4171-2022, 2022
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Based on observing system simulation experiments using a mesoscale-resolving model, we found that to significantly improve uncertainties and biases in carbon dioxide (CO2) mapping in the Southern Ocean, it is essential to resolve the seasonal cycle (SC) of the meridional gradient of CO2 through high frequency (at least daily) observations that also span the region's meridional axis. We also showed that the estimated SC anomaly and mean annual CO2 are highly sensitive to seasonal sampling biases.
Liliane Merlivat, Michael Hemming, Jacqueline Boutin, David Antoine, Vincenzo Vellucci, Melek Golbol, Gareth A. Lee, and Laurence Beaumont
Biogeosciences, 19, 3911–3920, https://doi.org/10.5194/bg-19-3911-2022, https://doi.org/10.5194/bg-19-3911-2022, 2022
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We use in situ high-temporal-resolution measurements of dissolved inorganic carbon and atmospheric parameters at the air–sea interface to analyse phytoplankton bloom initiation identified as the net rate of biological carbon uptake in the Mediterranean Sea. The shift from wind-driven to buoyancy-driven mixing creates conditions for blooms to begin. Active mixing at the air–sea interface leads to the onset of the surface phytoplankton bloom due to the relaxation of wind speed following storms.
Léa Olivier, Jacqueline Boutin, Gilles Reverdin, Nathalie Lefèvre, Peter Landschützer, Sabrina Speich, Johannes Karstensen, Matthieu Labaste, Christophe Noisel, Markus Ritschel, Tobias Steinhoff, and Rik Wanninkhof
Biogeosciences, 19, 2969–2988, https://doi.org/10.5194/bg-19-2969-2022, https://doi.org/10.5194/bg-19-2969-2022, 2022
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We investigate the impact of the interactions between eddies and the Amazon River plume on the CO2 air–sea fluxes to better characterize the ocean carbon sink in winter 2020. The region is a strong CO2 sink, previously underestimated by a factor of 10 due to a lack of data and understanding of the processes responsible for the variability in ocean carbon parameters. The CO2 absorption is mainly driven by freshwater from the Amazon entrained by eddies and by the winter seasonal cooling.
Hana Jurikova, Osamu Abe, Fuh-Kwo Shiah, and Mao-Chang Liang
Biogeosciences, 19, 2043–2058, https://doi.org/10.5194/bg-19-2043-2022, https://doi.org/10.5194/bg-19-2043-2022, 2022
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We studied the isotopic composition of oxygen dissolved in seawater in the South China Sea. This tells us about the origin of oxygen in the water column, distinguishing between biological oxygen produced by phytoplankton communities and atmospheric oxygen entering seawater through gas exchange. We found that the East Asian Monsoon plays an important role in determining the amount of oxygen produced vs. consumed by the phytoplankton, as well as in inducing vertical water mass mixing.
Richard P. Sims, Michael Bedington, Ute Schuster, Andrew J. Watson, Vassilis Kitidis, Ricardo Torres, Helen S. Findlay, James R. Fishwick, Ian Brown, and Thomas G. Bell
Biogeosciences, 19, 1657–1674, https://doi.org/10.5194/bg-19-1657-2022, https://doi.org/10.5194/bg-19-1657-2022, 2022
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The amount of carbon dioxide (CO2) being absorbed by the ocean is relevant to the earth's climate. CO2 values in the coastal ocean and estuaries are not well known because of the instrumentation used. We used a new approach to measure CO2 across the coastal and estuarine zone. We found that CO2 and salinity were linked to the state of the tide. We used our CO2 measurements and model salinity to predict CO2. Previous studies overestimate how much CO2 the coastal ocean draws down at our site.
Thi Tuyet Trang Chau, Marion Gehlen, and Frédéric Chevallier
Biogeosciences, 19, 1087–1109, https://doi.org/10.5194/bg-19-1087-2022, https://doi.org/10.5194/bg-19-1087-2022, 2022
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Air–sea CO2 fluxes and associated uncertainty over the open ocean to coastal shelves are estimated with a new ensemble-based reconstruction of pCO2 trained on observation-based data. The regional distribution and seasonality of CO2 sources and sinks are consistent with those suggested in previous studies as well as mechanisms discussed therein. The ensemble-based uncertainty field allows identifying critical regions where improvements in pCO2 and air–sea CO2 flux estimates should be a priority.
Charel Wohl, Anna E. Jones, William T. Sturges, Philip D. Nightingale, Brent Else, Brian J. Butterworth, and Mingxi Yang
Biogeosciences, 19, 1021–1045, https://doi.org/10.5194/bg-19-1021-2022, https://doi.org/10.5194/bg-19-1021-2022, 2022
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We measured concentrations of five different organic gases in seawater in the high Arctic during summer. We found higher concentrations near the surface of the water column (top 5–10 m) and in areas of partial ice cover. This suggests that sea ice influences the concentrations of these gases. These gases indirectly exert a slight cooling effect on the climate, and it is therefore important to measure the levels accurately for future climate predictions.
Jesse M. Vance, Kim Currie, John Zeldis, Peter W. Dillingham, and Cliff S. Law
Biogeosciences, 19, 241–269, https://doi.org/10.5194/bg-19-241-2022, https://doi.org/10.5194/bg-19-241-2022, 2022
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Long-term monitoring is needed to detect changes in our environment. Time series of ocean carbon have aided our understanding of seasonal cycles and provided evidence for ocean acidification. Data gaps are inevitable, yet no standard method for filling gaps exists. We present a regression approach here and compare it to seven other common methods to understand the impact of different approaches when assessing seasonal to climatic variability in ocean carbon.
Daniel J. Ford, Gavin H. Tilstone, Jamie D. Shutler, and Vassilis Kitidis
Biogeosciences, 19, 93–115, https://doi.org/10.5194/bg-19-93-2022, https://doi.org/10.5194/bg-19-93-2022, 2022
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This study identifies the most accurate biological proxy for the estimation of seawater pCO2 fields, which are key to assessing the ocean carbon sink. Our analysis shows that the net community production (NCP), the balance between photosynthesis and respiration, was more accurate than chlorophyll a within a neural network scheme. The improved pCO2 estimates, based on NCP, identified the South Atlantic Ocean as a net CO2 source, compared to a CO2 sink using chlorophyll a.
Birthe Zäncker, Michael Cunliffe, and Anja Engel
Biogeosciences, 18, 2107–2118, https://doi.org/10.5194/bg-18-2107-2021, https://doi.org/10.5194/bg-18-2107-2021, 2021
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Fungi are found in numerous marine environments. Our study found an increased importance of fungi in the Ionian Sea, where bacterial and phytoplankton counts were reduced, but organic matter was still available, suggesting fungi might benefit from the reduced competition from bacteria in low-nutrient, low-chlorophyll (LNLC) regions.
Jon Olafsson, Solveig R. Olafsdottir, Taro Takahashi, Magnus Danielsen, and Thorarinn S. Arnarson
Biogeosciences, 18, 1689–1701, https://doi.org/10.5194/bg-18-1689-2021, https://doi.org/10.5194/bg-18-1689-2021, 2021
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The Atlantic north of 50° N is an intense ocean sink area for atmospheric CO2. Observations in the vicinity of Iceland reveal a previously unrecognized Arctic contribution to the North Atlantic CO2 sink. Sustained CO2 influx to waters flowing from the Arctic Ocean is linked to their excess alkalinity derived from sources in the changing Arctic. The results relate to the following question: will the North Atlantic continue to absorb CO2 in the future as it has in the past?
Wei-Lei Wang, Guisheng Song, François Primeau, Eric S. Saltzman, Thomas G. Bell, and J. Keith Moore
Biogeosciences, 17, 5335–5354, https://doi.org/10.5194/bg-17-5335-2020, https://doi.org/10.5194/bg-17-5335-2020, 2020
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Dimethyl sulfide, a volatile compound produced as a byproduct of marine phytoplankton activity, can be emitted to the atmosphere via gas exchange. In the atmosphere, DMS is oxidized to cloud condensation nuclei, thus contributing to cloud formation. Therefore, oceanic DMS plays an important role in regulating the planet's climate by influencing the radiation budget. In this study, we use an artificial neural network model to update the global DMS climatology and estimate the sea-to-air flux.
Yuri Galletti, Silvia Becagli, Alcide di Sarra, Margherita Gonnelli, Elvira Pulido-Villena, Damiano M. Sferlazzo, Rita Traversi, Stefano Vestri, and Chiara Santinelli
Biogeosciences, 17, 3669–3684, https://doi.org/10.5194/bg-17-3669-2020, https://doi.org/10.5194/bg-17-3669-2020, 2020
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This paper reports the first data about atmospheric deposition of dissolved organic matter (DOM) on the island of Lampedusa. It also shows the implications for the surface marine layer by studying the impact of atmospheric organic carbon deposition in the marine ecosystem. It is a preliminary study, but it is pioneering and important for having new data that can be crucial in order to understand the impact of atmospheric deposition on the marine carbon cycle in a global climate change scenario.
Charel Wohl, Ian Brown, Vassilis Kitidis, Anna E. Jones, William T. Sturges, Philip D. Nightingale, and Mingxi Yang
Biogeosciences, 17, 2593–2619, https://doi.org/10.5194/bg-17-2593-2020, https://doi.org/10.5194/bg-17-2593-2020, 2020
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The oceans represent a poorly understood source of organic carbon to the atmosphere. In this paper, we present ship-based measurements of specific compounds in ambient air and seawater of the Southern Ocean. We present fluxes of these gases between air and sea at very high resolution. The data also contain evidence for day and night variations in some of these compounds. These measurements can be used to better understand the role of the Southern Ocean in the cycling of these compounds.
Rebecca L. Jackson, Albert J. Gabric, Roger Cropp, and Matthew T. Woodhouse
Biogeosciences, 17, 2181–2204, https://doi.org/10.5194/bg-17-2181-2020, https://doi.org/10.5194/bg-17-2181-2020, 2020
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Coral reefs are a strong source of atmospheric sulfur through stress-induced emissions of dimethylsulfide (DMS). This biogenic sulfur can influence aerosol and cloud properties and, consequently, the radiative balance over the ocean. DMS emissions may therefore help to mitigate coral physiological stress via increased low-level cloud cover and reduced sea surface temperature. The importance of DMS in coral physiology and climate is reviewed and the implications for coral bleaching are discussed.
Louise Delaigue, Helmuth Thomas, and Alfonso Mucci
Biogeosciences, 17, 547–566, https://doi.org/10.5194/bg-17-547-2020, https://doi.org/10.5194/bg-17-547-2020, 2020
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This paper reports on the first compilation and analysis of the surface water pCO2 distribution in the Saguenay Fjord, the southernmost subarctic fjord in the Northern Hemisphere, and thus fills a significant knowledge gap in current regional estimates of estuarine CO2 emissions.
Tim Fischer, Annette Kock, Damian L. Arévalo-Martínez, Marcus Dengler, Peter Brandt, and Hermann W. Bange
Biogeosciences, 16, 2307–2328, https://doi.org/10.5194/bg-16-2307-2019, https://doi.org/10.5194/bg-16-2307-2019, 2019
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We investigated air–sea gas exchange in oceanic upwelling regions for the case of nitrous oxide off Peru. In this region, routine concentration measurements from ships at 5 m or 10 m depth prove to overestimate surface (bulk) concentration. Thus, standard estimates of gas exchange will show systematic error. This is due to very shallow stratified layers that inhibit exchange between surface water and waters below and can exist for several days. Maximum bias occurs in moderate wind conditions.
Mingxi Yang, Thomas G. Bell, Ian J. Brown, James R. Fishwick, Vassilis Kitidis, Philip D. Nightingale, Andrew P. Rees, and Timothy J. Smyth
Biogeosciences, 16, 961–978, https://doi.org/10.5194/bg-16-961-2019, https://doi.org/10.5194/bg-16-961-2019, 2019
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We quantify the emissions and uptake of the greenhouse gases carbon dioxide and methane from the coastal seas of the UK over 1 year using the state-of-the-art eddy covariance technique. Our measurements show how these air–sea fluxes vary twice a day (tidal), diurnally (circadian) and seasonally. We also estimate the air–sea gas transfer velocity, which is essential for modelling and predicting coastal air-sea exchange.
Riley X. Brady, Nicole S. Lovenduski, Michael A. Alexander, Michael Jacox, and Nicolas Gruber
Biogeosciences, 16, 329–346, https://doi.org/10.5194/bg-16-329-2019, https://doi.org/10.5194/bg-16-329-2019, 2019
Stelios Myriokefalitakis, Akinori Ito, Maria Kanakidou, Athanasios Nenes, Maarten C. Krol, Natalie M. Mahowald, Rachel A. Scanza, Douglas S. Hamilton, Matthew S. Johnson, Nicholas Meskhidze, Jasper F. Kok, Cecile Guieu, Alex R. Baker, Timothy D. Jickells, Manmohan M. Sarin, Srinivas Bikkina, Rachel Shelley, Andrew Bowie, Morgane M. G. Perron, and Robert A. Duce
Biogeosciences, 15, 6659–6684, https://doi.org/10.5194/bg-15-6659-2018, https://doi.org/10.5194/bg-15-6659-2018, 2018
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The first atmospheric iron (Fe) deposition model intercomparison is presented in this study, as a result of the deliberations of the United Nations Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP; http://www.gesamp.org/) Working Group 38. We conclude that model diversity over remote oceans reflects uncertainty in the Fe content parameterizations of dust aerosols, combustion aerosol emissions and the size distribution of transported aerosol Fe.
Liliane Merlivat, Jacqueline Boutin, David Antoine, Laurence Beaumont, Melek Golbol, and Vincenzo Vellucci
Biogeosciences, 15, 5653–5662, https://doi.org/10.5194/bg-15-5653-2018, https://doi.org/10.5194/bg-15-5653-2018, 2018
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The fugacity of carbon dioxide in seawater (fCO2) was measured hourly in the surface waters of the NW Mediterranean Sea during two 3-year sequences separated by 18 years. A decrease of pH of 0.0022 yr−1 was computed. About 85 % of the accumulation of dissolved inorganic carbon (DIC) comes from chemical equilibration with increasing atmospheric CO2; the remaining 15 % accumulation is consistent with estimates of transfer of Atlantic waters through the Gibraltar Strait.
Amanda R. Fay, Nicole S. Lovenduski, Galen A. McKinley, David R. Munro, Colm Sweeney, Alison R. Gray, Peter Landschützer, Britton B. Stephens, Taro Takahashi, and Nancy Williams
Biogeosciences, 15, 3841–3855, https://doi.org/10.5194/bg-15-3841-2018, https://doi.org/10.5194/bg-15-3841-2018, 2018
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The Southern Ocean is highly under-sampled and since this region dominates the ocean sink for CO2, understanding change is critical. Here we utilize available observations to evaluate how the seasonal cycle, variability, and trends in surface ocean carbon in the well-sampled Drake Passage region compare to that of the broader subpolar Southern Ocean. Results indicate that the Drake Passage is representative of the broader region; however, additional winter observations would improve comparisons.
Cui-Ci Sun, Martin Sperling, and Anja Engel
Biogeosciences, 15, 3577–3589, https://doi.org/10.5194/bg-15-3577-2018, https://doi.org/10.5194/bg-15-3577-2018, 2018
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Biogenic gel particles such as transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP) are important components in the sea-surface microlayer (SML). Their potential role in air–sea gas exchange and in primary organic aerosol emission has generated considerable research interest. Our wind wave channel experiment revealed how wind speed controls the accumulation and size distribution of biogenic gel particles in the SML.
N. Precious Mongwe, Marcello Vichi, and Pedro M. S. Monteiro
Biogeosciences, 15, 2851–2872, https://doi.org/10.5194/bg-15-2851-2018, https://doi.org/10.5194/bg-15-2851-2018, 2018
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Here we analyze seasonal cycle of CO2 biases in 10 CMIP5 models in the SO. We find two main model biases; exaggeration of primary production such that biologically driven DIC changes mainly regulates FCO2 variability, and an overestimation of the role of solubility, such that changes in temperature dominantly drive FCO2 seasonal changes to an extent of opposing biological CO2 uptake in spring. CMIP5 models show greater zonal homogeneity in the seasonal cycle of FCO2 than observational products.
Allison R. Moreno, George I. Hagstrom, Francois W. Primeau, Simon A. Levin, and Adam C. Martiny
Biogeosciences, 15, 2761–2779, https://doi.org/10.5194/bg-15-2761-2018, https://doi.org/10.5194/bg-15-2761-2018, 2018
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To bridge the missing links between variable marine elemental stoichiometry, phytoplankton physiology and carbon cycling, we embed four environmentally controlled stoichiometric models into a five-box ocean model. As predicted each model varied in its influence on the biological pump. Surprisingly, we found that variation can lead to nonlinear controls on atmospheric CO2 and carbon export, suggesting the need for further studies of ocean C : P and the impact on ocean carbon cycling.
Luke Gregor, Schalk Kok, and Pedro M. S. Monteiro
Biogeosciences, 15, 2361–2378, https://doi.org/10.5194/bg-15-2361-2018, https://doi.org/10.5194/bg-15-2361-2018, 2018
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The Southern Ocean accounts for a large portion of the variability in oceanic CO2 uptake. However, the drivers of these changes are not understood due to a lack of observations. In this study, we used an ensemble of gap-filling methods to estimate surface CO2. We found that winter was a more important driver of longer-term variability driven by changes in wind stress. Summer variability of CO2 was driven primarily by increases in primary production.
Erik T. Buitenhuis, Parvadha Suntharalingam, and Corinne Le Quéré
Biogeosciences, 15, 2161–2175, https://doi.org/10.5194/bg-15-2161-2018, https://doi.org/10.5194/bg-15-2161-2018, 2018
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Thanks to decreases in CFC concentrations, N2O is now the third-most important greenhouse gas, and the dominant contributor to stratospheric ozone depletion. Here we estimate the ocean–atmosphere N2O flux. We find that an estimate based on observations alone has a large uncertainty. By combining observations and a range of model simulations we find that the uncertainty is much reduced to 2.45 ± 0.8 Tg N yr−1, and better constrained and at the lower end of the estimate in the latest IPCC report.
Sayaka Yasunaka, Eko Siswanto, Are Olsen, Mario Hoppema, Eiji Watanabe, Agneta Fransson, Melissa Chierici, Akihiko Murata, Siv K. Lauvset, Rik Wanninkhof, Taro Takahashi, Naohiro Kosugi, Abdirahman M. Omar, Steven van Heuven, and Jeremy T. Mathis
Biogeosciences, 15, 1643–1661, https://doi.org/10.5194/bg-15-1643-2018, https://doi.org/10.5194/bg-15-1643-2018, 2018
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We estimated monthly air–sea CO2 fluxes in the Arctic Ocean and its adjacent seas north of 60° N from 1997 to 2014, after mapping pCO2 in the surface water using a self-organizing map technique. The addition of Chl a as a parameter enabled us to improve the estimate of pCO2 via better representation of its decline in spring. The uncertainty in the CO2 flux estimate was reduced, and a net annual Arctic Ocean CO2 uptake of 180 ± 130 Tg C y−1 was determined to be significant.
Alizée Roobaert, Goulven G. Laruelle, Peter Landschützer, and Pierre Regnier
Biogeosciences, 15, 1701–1720, https://doi.org/10.5194/bg-15-1701-2018, https://doi.org/10.5194/bg-15-1701-2018, 2018
Chao Zhang, Huiwang Gao, Xiaohong Yao, Zongbo Shi, Jinhui Shi, Yang Yu, Ling Meng, and Xinyu Guo
Biogeosciences, 15, 749–765, https://doi.org/10.5194/bg-15-749-2018, https://doi.org/10.5194/bg-15-749-2018, 2018
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This study compares the response of phytoplankton growth in the northwest Pacific to those in the Yellow Sea. In general, larger positive responses of phytoplankton induced by combined nutrients (in the subtropical gyre of the northwest Pacific) than those induced by a single nutrient (in the Kuroshio Extension and the Yellow Sea) from the dust are observed. We also emphasize the importance of an increase in bioavailable P stock for phytoplankton growth following dust addition.
Goulven G. Laruelle, Peter Landschützer, Nicolas Gruber, Jean-Louis Tison, Bruno Delille, and Pierre Regnier
Biogeosciences, 14, 4545–4561, https://doi.org/10.5194/bg-14-4545-2017, https://doi.org/10.5194/bg-14-4545-2017, 2017
Melchor González-Dávila, J. Magdalena Santana Casiano, and Francisco Machín
Biogeosciences, 14, 3859–3871, https://doi.org/10.5194/bg-14-3859-2017, https://doi.org/10.5194/bg-14-3859-2017, 2017
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The Mauritanian–Cap Vert upwelling is shown to be sensitive to climate change forcing on upwelling processes, which strongly affects the CO2 surface distribution, ocean acidification rates, and air–sea CO2 exchange. We confirmed an upwelling intensification, an increase in the CO2 outgassing, and an important decrease in the pH of the surface waters. Upwelling areas are poorly studied and VOS lines are shown as one of the most significant contributors to our knowledge of the ocean's response.
Rachel Hussherr, Maurice Levasseur, Martine Lizotte, Jean-Éric Tremblay, Jacoba Mol, Helmuth Thomas, Michel Gosselin, Michel Starr, Lisa A. Miller, Tereza Jarniková, Nina Schuback, and Alfonso Mucci
Biogeosciences, 14, 2407–2427, https://doi.org/10.5194/bg-14-2407-2017, https://doi.org/10.5194/bg-14-2407-2017, 2017
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This study assesses the impact of ocean acidification on phytoplankton and its synthesis of the climate-active gas dimethyl sulfide (DMS), as well as its modulation, by two contrasting light regimes in the Arctic. The light regimes tested had no significant impact on either the phytoplankton or DMS concentration, whereas both variables decreased linearly with the decrease in pH. Thus, a rapid decrease in surface water pH could alter the algal biomass and inhibit DMS production in the Arctic.
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Short summary
The Arabian Sea is a natural CO2 source to the atmosphere, but previous work highlights discrepancies between data and models in estimating air–sea CO2 flux. In this study, we use a regional ocean model, achieve a flux closer to available data, and break down the seasonal cycles that impact it, with one result being the great importance of monsoon winds. As demonstrated in a meta-analysis, differences from data still remain, highlighting the great need for further regional data collection.
The Arabian Sea is a natural CO2 source to the atmosphere, but previous work highlights...
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