Abstract. The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing surface-to-bottom ocean biogeochemical observations determined through chemical analysis of discrete bottle samples, with an emphasis on seawater inorganic carbon chemistry and related variables. Version 3 of GLODAP comprises data from 1181 cruises, spanning more than 50 years of observations (1972–2023). It includes all data from the previous GLODAPv2.2023 (Lauvset et al., 2024) together with newly added data from 57 cruises. For all cruises, 13 core variables (temperature, salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, CFC-11, CFC-12, CFC-113, CCl₄, and SF6) have undergone extensive quality control with particular focus on the identification and removal of systematic differences between cruises. The data are available in two formats: (i) as submitted by the data originators, converted to World Ocean Circulation Experiment (WOCE) exchange format, and (ii) as a merged data product in which adjustments have been applied. These adjustments were determined using crossover analyses in combination with a newly developed global inversion method, the furthest-first routine. The applied adjustments are intended to remove systematic differences arising from differences in measurement methods, calibration, and/or data-handling practices, while preserving known or likely temporal trends and natural variability. The consistency of the adjusted data product is estimated to be 0.0013 for salinity, 0.7 % for oxygen, 0.4 % for nitrate, 0.5 % for silicate, 0.5 % for phosphate, 1.2 µmol kg⁻¹ for dissolved inorganic carbon, and 1.4 µmol kg⁻¹ for total alkalinity. Consistency estimates could not be derived for transient tracers, but they are believed to be consistent to better than 5 % (10 % for SF₆). The enhanced consistency enables different datasets to be used together with greater confidence. Newly introduced cruise-specific uncertainty estimates for all core variables provide more granular quantifications of remaining cruise-to-cruise inconsistencies. Additional variables, including pH, discrete CO₂ fugacity (fCO₂), isotopic tracers, and others, were not subjected to secondary quality control but are included in the data product. The original data, their documentation (metadata), and DOIs are available through the Ocean Carbon and Acidification Data System (OCADS) of NOAA’s National Centers for Environmental Information (NCEI), which also hosts the merged data product. All secondary quality control decisions and supporting information can be found in the online adjustment table (https://glodapv3.geomar.de, last accesses 26.06.2026). The product is distributed as a single global file and as four regional subsets (Arctic, Atlantic, Indian, and Pacific Oceans) under https://doi.org/10.25921/m6tp-mj50 (Lange et al., 2026). These adjusted files also include ancillary and approximated data obtained through interpolation or calculation from measured data.

We examined the surface total alkalinity (AT) and salinity (SSS) distributions and their relationship along the southwestern South Atlantic Ocean margin off the Brazilian coast. In situ hydrographic data from shelf and slope stations were measured during three oceanographic cruises in October 2014 (austral spring), April 2018 (austral autumn) and June 2019 (austral winter). The northern portion of the study area lies within the Brazil Current domain, transporting warm and salty Tropical Water, while further south the Subtropical Shelf Water and the freshwater plume derived from the Patos Lagoon and Plata River influence the temperature, salinity, and AT distribution. The present study aimed to determine the relationship between AT and SSS to establish a model for reconstructing a surface time series for the marine carbonate system in the undersampled region of the subtropical southwestern South Atlantic Ocean margin. The AT - SSS relationship showed a significant positive linear relationship (r2=0.76), reflecting both current-dominated (i.e., outer and northernmost stations) and freshwater mixing processes (i.e., inner and southernmost stations and continental inputs). The observed AT values were well correlated with the reported ranges for the tropical and subtropical South Atlantic Ocean, and the predicted AT obtained from the Global Ocean Data Analysis Project and the World Ocean Database 2013 SSS data confirmed lower AT in shelf waters under the influence of continental inputs, which increased towards the outer shelf and slope. Finally, the newly proposed regional AT - SSS relationship improves previous linear regressions for the southwestern Atlantic Ocean margin.

The southwestern South Atlantic Ocean is an important global sink of atmospheric carbon dioxide (CO2), driven by increased primary productivity in a nearby region where oligotrophic warm currents converge with nutrient-rich cold waters. However, uncertainties remain regarding CO2 dynamics and the role of physical processes in CO2 uptake across this region. Here, we assess variations in surface partial pressure of CO2 (pCO2) and air–sea CO2 fluxes in the Southwest Atlantic, along a transect from the continental shelf to the open ocean at 34.5°S during austral autumn 2018 and winter 2019. High-resolution spatial measurements of the temperature, salinity, and molar fraction of surface CO2 were conducted. In autumn 2018, the shelf region acted as a source of CO2 to the atmosphere (median of 3.2 mmol CO2 m-2 d-1), which was partially offset by a sink (median of –2.5 mmol CO2 m-2 d-1) in the open ocean. In contrast, the entire transect in winter 2019 presented median CO2 emissions of ~1.5 mmol CO2 m-2 d-1, which differs from climatological estimates. The spatial and seasonal variations in surface ocean pCO2 were linked to variable hydrodynamic processes, including water masses and mesoscale structures. Our findings reveal that, in one of the most productive oceanic waters worldwide, pCO2 may be influenced by distinct continental inputs (e.g., rivers, runoff, and groundwater discharge) and water masses (e.g., Tropical Water, Plata Plume Water and Subtropical Shelf Water). Therefore, the local hydrodynamic processes can modulate high spatial and seasonal variability in CO2 exchange at the ocean–atmosphere interface, with potential implications for regional and global carbon budgets. General results, such as climatological, cannot fully capture the influence of regional upwelling and continental water input, which highlights the importance of high-resolution regional observations.

Coastal waters play a pivotal role in the global carbon cycle, showing increased short‐term variability of dissolved oxygen saturation (DOsat) and partial pressure of greenhouse gases like carbon dioxide ( p CO 2 ), especially in underrepresented tropical eutrophic environments. Here, we conducted high‐frequency (1‐min interval) diel measurements of surface DOsat and p CO 2 in Guanabara Bay, Brazil, a highly nutrient‐enriched coastal ecosystem. The predominant metabolic controls on p CO 2 were revealed by its strong negative correlation with DOsat. Air–sea CO 2 fluxes derived from high‐frequency diel sampling showed emissions of 533 mmol C m −2 annually. Conventional estimates based on daylight‐only measurements were ~73% and 319% higher in the morning (10:00–12:00 h and sunrise–8:00 h, respectively) or ~172% and 244% lower in the afternoon (12:00–14:00 h and 14:00–16:00 h, respectively). Our findings indicate that rapid diel shifts between CO 2 sinks and sources in eutrophic coastal waters can introduce significant uncertainty in estimating air–water CO 2 fluxes from regional to global carbon budgets.

In this study, we investigated the spatial and temporal distribution of phytoplankton functional groups in the tropical Atlantic by analyzing temperature, salinity, and nutrient gradients under the influence of the Intertropical Convergence Zone (ITCZ, 5-10° N) and El Niño-Southern Oscillation (ENSO) events (La Niña/El Niño) of 2017 and 2018. Environmental gradients provide habitat-specific scenarios for phytoplankton functional diversity, which determine the composition of populations on both spatial and temporal scales. Using microscopy, we evaluated nano- and microphytoplankton assemblages through qualitative and quantitative analyses. Higher diazotrophic cyanobacteria abundance and higher functional richness and functional dispersion were observed in 2017 (La Niña). Our results show that nutrient availability associated with local hydrography, temperature, and salinity influenced the distribution of diazotrophic cyanobacteria. The El Niño event of 2018 was characterized by higher sea surface temperatures and weaker convergence, impacting nutrient availability and altering the N:P ratio in the euphotic zone. These alterations affected the functional traits and species richness in the ITCZ, leading to discrete gradients across sea surface temperature and nutrient availability. Conversely, the La Niña event of 2017 was associated with decreased sea surface temperature and lower influence of the Amazon river plume, which added diazotroph-related functional traits. This study highlights the interplay of environmental factors in shaping phytoplankton communities, emphasizing the importance of understanding their dynamics and biogeography in offshore tropical waters.

Diatoms represent the most abundant group of microorganisms carried by ballast water; they present great invasive potential and remain viable after long periods of darkness. This is likely the dispersal route of Coscinodiscus wailesii, a species native to the Indian Ocean or Pacific Ocean, which has become invasive in various global regions. Considering that this species is invasive and potentially harmful, we carried out potential distribution modeling with the aim of assessing the effects of global warming on the geographical distribution of C. wailesii. In this study, we also present the first record of a C. wailesii bloom on the coast of Northeast Brazil, generating low phytoplankton diversity. The distribution models indicated an expansion of the climatic niches for the occurrence of C. wailesii in the SSP2-4.5 scenario (intermediate pathway of greenhouse gas emissions), there was a more marked increase in the climatic niches from the present until 2030, followed by slower growth until 2090. These expansions are more evident in the SSP5-8.5 scenario (greater greenhouse gas emissions) under conditions of more intense global warming. We highlight that these predictions indicate a potential increase in the distribution and frequency of C. wailesii blooms, with important ecological effects. Algal blooms promote greater availability of dissolved oxygen in their initial phase, in addition to representing a temporary carbon sink. However, because C. wailesii is a potentially harmful species, their blooms can cause damage to the ecosystem, such as loss of planktonic diversity and anoxic conditions.

The ocean plays an essential role in regulating the global climate, absorbing around 25 % of global CO2 emissions. Scientific knowledge of the ocean's capacity as a carbon sink is therefore essential for policy-making at the national and international level. However, the capacity of the existing marine science system to deliver this information at sufficiently high quality, without geographical and temporal gaps, and with equitable contributions by and access for less affluent national science systems, is far from assured. This contribution applies the six guiding principles of Open Science as a yardstick for science in the service of society to assess the current state of marine (carbon) science, pointing out strengths and shortcomings, and deriving specific recommendations for science policy. This contribution results from a three-year interdisciplinary research project with researchers from Brazil and Germany and was discussed within the UN Ocean Decade Program Ocean Acidification Research for Sustainability (OARS) to validate the applicability of insights and recommendations beyond these particular contexts.

The Western Tropical Atlantic Ocean (WTAO) is crucial for understanding CO2 dynamics due to inputs from major rivers (Amazon and Orinoco), substantial rainfall from the Intertropical Convergence Zone (ITCZ), and CO2-rich waters from equatorial upwelling. This study, spanning 1998 to 2018, utilized sea surface temperature (SST) and sea surface salinity (SSS) data from the PIRATA buoy at 8°N 38°W to reconstruct the surface marine carbonate system. Empirical models derived total alkalinity (TA) and dissolved inorganic carbon (DIC) from SSS, with subsequent estimation of pH and fCO2 from TA, DIC, SSS, and SST data. Linear trend analysis showed statistically significant temporal trends: DIC and fCO2 increased at a rate of 0.7 µmol kg-1 year-1 and 1.539 µatm year-1, respectively, and pH decreased at a rate of -0.001 pH units year-1, although DIC did not show any trend after data was de-seasoned. Rainfall analysis revealed distinct dry (July to December) and wet (January to June) seasons, aligning with lower and higher freshwater influence on the ocean surface, respectively. TA, DIC, and pH correlated positively with SSS, exhibiting higher values during the dry season and lower values during the wet season. Conversely, fCO2 correlated positively with SST, showcasing higher values during the wet season and lower values during the dry season. This emphasizes the influential roles of SSS and SST variability in CO2 solubility within the region. Finally, we have analysed the difference between TA and DIC (TA-DIC) as an indicator for ocean acidification and found a decreasing trend of -0.93 ± 0.02 μmol kg-1 year-1, reinforcing the reduction in the surface ocean buffering capacity in this area. All trends found for the region agree with data from other stations in the tropical and subtropical Atlantic Ocean. In conclusion, the use of empirical models proposed in this study has proven to help filling the gaps in marine carbonate system data in the Western Tropical Atlantic.

The Brazilian Equatorial Shelf (BES) is one among the macrotidal regions worldwide. This study used a high-resolution numerical configuration of the ocean model ROMS (Regional Ocean Modeling System) forced with realistic surface and lateral forcing, as well as with tides and river discharges. Tidal heights of more than 2 m were found in three regions in BES due to the large tidal amplification across the estuarine channels inside each region: Amazon, Pará, and Maranhão, and for a considerable time fraction. Heights between 4 and 5 m occurred with a frequency greater than 20%–30% in some regions. All hypothetical barrages proposed in this study were capable of an annual power production, in two-way mode, higher than La Rance (533 GWh year−1, two-way operation, France) and Sihwa (553 GWh year−1, flood-only operation, South Korea), except one with the same production as Sihwa barrage. The installation effort was evaluated using the Gibrat ratio, the ratio between the length of the barrage and its annual energy production. Among the proposed barrages, the most efficient ones have an annual power generation greater than 1500 GWh year−1 and a Gibrat ratios between 1.17 and 3.26, much lower than the Gibrat ratio of Sihwa tidal barrage.

Dissolved organic carbon (DOC) is a key component of the biogeochemical carbon cycle in the Southern Ocean. However, there are still significant gaps in understanding the role of DOC in polar environments, due to the limitations of spatiotemporal sampling. In this study, we investigated the regional aspects controlling the distribution and diffusive and advective fluxes of DOC along the northern Antarctic Peninsula (NAP) during austral late summers of 1995 and between 2015 and 2019. DOC concentrations ranged from 33.1 to 157.6 mu mol kg-1. The NAP showed regional differences in both its hydrographicconditions and DOC distribution. Theregional variability reflected the main biogeochemical sources and fates of DOC associated with the Antarctic Circumpolar Current inflows, the Weddell Gyre transport and the meltwater input. The intensity of the advective fluxes of DOC was 106 times greater than the diffusive fluxes. However, ocean fronts along NAP environments are mesoscale structures for observations of downward and upward diffusive fluxes of DOC. This study adds insights on the role of DOC as a proxy for a better understanding of the coupling between physical and biogeochemical processes over time in an environment sensitive to climate change.

The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface to bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2023 is an update of the previous version, GLODAPv2.2022 (Lauvset et al., 2022). The major changes are as follows: data from 23 new cruises were added. In addition, a number of changes were made to the data included in GLODAPv2.2022. GLODAPv2.2023 includes measurements from more than 1.4 million water samples from the global oceans collected on 1108 cruises. The data for the now 13 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, chlorofluorocarbon-11 (CFC-11), CFC-12, CFC-113, CCl4, and SF6) have undergone extensive quality control with a focus on the systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but converted to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For the present annual update, adjustments for the 23 new cruises were derived by comparing those data with the data from the 1085 quality-controlled cruises in the GLODAPv2.2022 data product using crossover analysis. SF6 data from all cruises were evaluated by comparison with CFC-12 data measured on the same cruises. For nutrients and ocean carbon dioxide (CO2), chemistry comparisons to estimates based on empirical algorithms provided additional context for adjustment decisions. The adjustments that we applied are intended to remove potential biases from errors related to measurement, calibration, and data-handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg−1 in dissolved inorganic carbon, 4 µmol kg−1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5 % in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments. The original data, their documentation, and DOI codes are available at the Ocean Carbon and Acidification Data System of NOAA National Centers for Environmental Information (NCEI), which also provides access to the merged data product. This is provided as a single global file and as four regional ones – the Arctic, Atlantic, Indian, and Pacific oceans – under https://doi.org/10.25921/zyrq-ht66 (Lauvset et al., 2023). These bias-adjusted product files also include significant ancillary and approximated data, which were obtained by interpolation of, or calculation from, measured data. This living data update documents the GLODAPv2.2023 methods and provides a broad overview of the secondary quality control procedures and results.

The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples.GLODAPv2.20232 is an update of the previous version, GLODAPv2.20221(Lauvset et al., 20221).The major changes are as follows: data from 96 23 new cruises were added, data coverage was extended until 2021, and for the first time we performed secondary quality control on all sulfur hexafluoride (SF6) data.In addition, a number of changes were made to data included in GLODAPv2.20221.These changes affect specifically the SF6 data, which are now subjected to secondary quality control, and carbon data measured on board the RV Knorr in the Indian Ocean in 1994-1995 which are now adjusted using certified reference material (CRM) measurements made at the time.GLODAPv2.20232includes measurements from almost more than1.4 million water samples from the global oceans collected on 11081085 cruises.The data for the now 13 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, chlorofluorocarbon-11 (CFC-11), CFC-12, CFC-113, CCl4, and SF6) have undergone extensive quality control with a focus on systematic evaluation of bias.The data are available in two formats: (i) as submitted by the data originator but converted to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias.For the present annual update, adjustments for the 2396 new cruises were derived by comparing those data with the data from the 989 1085 quality-controlled cruises in the GLODAPv2.20221data product using crossover analysis.SF6 data from all cruises were evaluated by comparison with CFC-12 data measured on the same cruises.For nutrients and ocean carbon dioxide (CO2) chemistry comparisons to estimates based on empirical algorithms provided additional context for adjustment decisions.The adjustments that we applied are intended to remove potential biases from errors related to measurement, calibration, and data handling practices without removing known or likely time trends or variations in the variables evaluated.The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 mol kg -1 in dissolved inorganic carbon, 4 mol kg -1 in total alkalinity, 0.01-0.02 in pH (depending on region), and 5 % in the halogenated transient tracers.The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments.The original data,

EDITORIAL article Front. Mar. Sci., 23 January 2023Sec. Physical Oceanography Volume 10 - 2023 | https://doi.org/10.3389/fmars.2023.1137809

Subpolar coastal waters are key hotspots in the global carbon cycle. However, the small-scale distribution of partial pressure of carbon dioxide (pCO2) in these environments and the physical and biological controls underlying this variability are still poorly understood. Here, we examine simultaneous high-resolution spatial measurements of wind speed and pCO(2), temperature, salinity, and in-vivo chlorophyll-a fluorescence (chl-a fluo, a proxy of phytoplankton biomass) in surface waters that were obtained during an oceanographic survey in the Argentinian Beagle Channel (subantarctic Atlantic Patagonian) in early fall 2017. The 240 km study transect (centered at 55 degrees S - 67 degrees W) was divided into two zones: (A1) The Beagle Channel innermost portion, semi-enclosed and subject to strong continental influence and (A2) its eastern outlet towards the open Southwest Atlantic. Discrete seawater samples were also collected for apparent oxygen utilization (AOU), nutrients and pH measurements. High-resolution spatial measurements revealed the persistence of pCO(2) below atmospheric equilibrium, increasing in median (interquartile range 25-75%) from 314 mu atm in the inner Beagle Channel (A1) to 348 mu atm towards the adjacent open sea (A2). A decrease in atmospheric CO2 sequestration was associated with an increase in water temperature from 9.5 degrees C to 10.7 degrees C, salinity from 30.8 to 32.5, and chl-a fluo from 2.24 to 2.91 mg m(-3) along the coastal-offshore gradient. Low AOU and nutrient levels were found in regions inside the channel. Indeed, the relationships between CO2 and temperature or salinity were significantly different from those expected from the theoretical solubility effect, indicating a dominance of metabolic over physicochemical controls on this gas. Moreover, physical factors such as vertical stratification contributed to the variable surface pCO2 values. These findings reveal the existence of short-scale spatial variability of CO2 in the Beagle Channel, improving our understanding of the multiple controls on atmospheric carbon sequestration in extensive subpolar continental shelves.

Measurements of the marine carbonate system on tropical and subtropical continental margins are poorly distributed in space and time, with many uncertainties persisting regarding the role of carbon exchanges at the ocean-atmosphere interface in these areas. To calculate sea-to-air CO2 fluxes in Marine Ecoregions along the Brazilian continental margin (4 & DEG;N to 34 & DEG;S), we used data from the Surface Ocean CO2 Atlas (SOCAT v2020), collected up to 400 km from the coast, at the surface (5 m), between 1991 and 2018, with the aim of investigating the role of ecoregions as potential sinks or sources of atmospheric CO2. The temperature and salinity of seawater presented variability in the north-south direction mainly because of the broad latitudinal range, reflecting typical patterns of tropical (T = 27.4 & DEG;C & PLUSMN;1.49; S = 36.4 & PLUSMN;1.91) and subtropical waters (T = 22.8 & DEG;C & PLUSMN;3.41; S = 35 & PLUSMN;2.91), in addition to the greater or lesser influence of river inputs in each ecoregion. The pCO2 values in the surface waters varied from 121.81 (Amazon) to 478.92 & mu;atm (Eastern), differing significantly between ecoregions and showing an expected decadal increasing trend, both in the atmosphere and in the seawater. The calculated values of CO2 fluxes showed non-homogeneous spatio-temporal variations, from-24.37 mmol m-2d-1 (Rio Grande) to 9.87 mmol m- 2 d-1 (Southeastern). Throughout the analyzed time series, we observed that the Northeast, Amazon and Eastern ecoregions acted predominantly as sources of CO2 and the Southeastern ecoregions and, mainly, Rio Grande, acted predominantly as sinks of atmospheric CO2.

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SOURCE OR SINK? A REVIEW OF THE CO2 FLUXES AT THE BRAZILIAN CONTINENTAL SHELF. Studies of global carbon balance estimates are still incipient in the oceans of the Southern Hemisphere, mainly in coastal areas and continental shelf. Even in Brazil, despite its continental proportion coastline, there is still a great inconsistency in studies on the marine carbonate system and CO2 fluxes at the air-sea interface. This article presents a review of studies on CO2 fluxes on the coast of Brazil, published between the years 2000 and 2022, aiming to map the distribution of CO2 fluxes on the Brazilian continental shelf, to understand its role as a source or sink of CO2. In general, large-scale studies show that the Brazilian shelf exhibits a latitudinal variation of air-sea CO2 fluxes, behaving mainly as a source in the north, where there is no influence of the Amazon River plume, and as a sink in the south portion. We also identified there is a strong influence on the occurrence of mesoscale and synoptic oceanographic and meteorological events, and the presence of different ecosystems, which can change the behavior of CO2 fluxes locally. However, there are still many data gaps along the continental shelf, as well as in different seasons for the entire coast.