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Argo floats have been deployed in the global ocean for over 20 years. The Core mission of the Argo program (Core Argo) has contributed well over 2 million profiles of salinity and temperature of the upper 2000 m of the water column for a variety of operational and scientific applications. Core Argo floats have evolved such that the program currently consists of more than eight types of Core Argo float, some of which belong to second or third generation developments, three unique satellite communication systems (Argos, Iridium and Beidou) and two types of Conductivity, Temperature and Depth (CTD) sensor systems (Seabird and RBR). This, together with a well-established data management system, delayed mode data quality control, FAIR and open data access, make the program a very successful ocean observing network. Here we present Part 1 of the Best Practices for Core Argo floats in terms of how users can get started in the program, recommended metadata parameters and the data management system. The objective is to encourage new and developing scientists, research teams and institutions to contribute to the OneArgo Program, specifically to the Core Argo mission. Only by leveraging sustained contributions from current Core Argo float groups with new and emerging Argo teams and users who are eager to get involved and are actively encouraged to do so, can the OneArgo initiative be realized. This paper presents a list of best practices to get started in the program, set up the recommended metadata, implement the data management system with the aim to encourage new scientists, countries and research teams to contribute to the OneArgo Program.

Following on from Part 1: Best Practices for Core Argo floats - Getting started and data considerations, we present Part 2: Best Practices for Core Argo floats in terms of physical handling and deployments and recommended metadata parameters. The objective is to encourage new and developing scientists, research teams and institutions to contribute to the OneArgo Program through increased deployments regionally, specifically to the Core Argo mission. Only by leveraging sustained contributions of current Core Argo float groups with new and emerging Argo teams and users, can the OneArgo initiative be realized. This paper makes involvement with the Core Argo mission smoother by providing a framework endorsed by a wide community for these observations.

The ocean regulates the exchange, storage of carbon dioxide, plays a key role in global control of Earth climate and life, absorbs most of the heat excess from greenhouse gas emissions and provides a remarkable number of resources for the human being. Most of the geo-hazards occur in oceanic areas. Thus, high-quality systematic observations are necessary tools for improving our understanding, and subsequent assimilation to provide early warning systems. A holistic scientific approach for the understanding of the ocean’s interrelated processes requires coordinated and complementary monitoring and observation programmes. Research Infrastructures (RIs) are large-scale facilities that provide resources and services for the scientific communities to conduct high-level research and foster innovation. RIs benefit from strong governance and multi-annual funding from their member states with operational life spans in decades. RIs promote knowledge, outreach and education to public, private, and policy stakeholders, and they play a key role in enabling and developing research in all scientific domains and currently represent a growing share of coordinated investment in research, and also in providing essential observations to operational services such as Copernicus. They are strategically important for Europe to lead a global movement towards a data-driven, interconnected, open digital twin that brings together different disciplines, clean technologies, public and private sectors and a broad scientific/technological community, as well as education and training. In Europe several marine RIs have been established, which are maintained by national and European Union (EU) resources. The aims of these infrastructures are aligned with the key priorities of the UN Decade of Ocean Science for Sustainable Development; and with the new European Research Area (ERA) Policy Agenda annexed to the Council conclusions on the ERA governance1, which set out 20 concrete actions for 2022-2024 to

Euro-Argo strategy in the context of the OneArgo new international design

This deliverable presents the Final Assessment of the observation and thematic networks as those represented in work package 3 of EuroSea, taking as a reference the information on Deliverable 3.2 Observing Network Initial Assessment. Following the same approach with D3.2 the original questionnaire was modified accordingly in order to depict the progress made on the same Network Attributes, Commitments and Benefits following the GOOS, OCG guidelines. The unforeseen COVID-19 pandemic had significant effects upon WP3 activities since the main mechanism foreseen to advance progress within the different networks was the organization of in person workshops. Moreover, adequate funds were allocated towards this in order to promote inclusivity and participation. Adapting to the new situation the first series of workshops had to be changed into online only events which despite the inherent difficulty, proved to have significant advantages as well. In particular they gave the opportunity for a significant number of people to join from all around the globe and participate in the events (for example the Sea Level WS). Another challenge proved to be the variability within some networks with sub-components or sub-groups having significantly different characteristics. In particular Eulerian platforms comprise a wide range of platforms - fixed moorings, surface buoys, cable bottom platforms - with some of them being part of mature and well-developed networks (OceanSITES, EMSO etc) while other are loose partners of on-going programs and projects (JERICO RI, coastal buoys). EuroSea activities had a significant positive impact on all the observing and thematic networks, actively promoting synergies and collaboration, with most of them successfully reaching Framework Processes Readiness Criteria Level 7 and above. Although progress at many different aspects must continue beyond EuroSea, it is important that the framework has been set. It is thus suggested that an annual evaluation/asses

Argo floats have been deployed in the global ocean for over 20 years. The Core mission of the Argo program (Core Argo) has contributed well over 2 million profiles of salinity and temperature of the upper 2000 m for a variety of operational and scientific applications. Core Argo floats have evolved such that the program currently consists of more than eight types of Core Argo float, some of which belong to second or third generation developments, three unique satellite communication systems and two types of Conductivity, Temperature and Depth (CTD) sensor systems. Coupled with a well-established data management system, with delayed mode quality control, makes for a very successful ocean observing network. Here we present the Best Practices for Core Argo floats in terms of float types, physical handling and deployments, recommended metadata parameters and the data management system. The objective is to encourage new and developing scientists, research teams and institutions to contribute to the OneArgo Program, specifically to the Core Argo mission. Only by leveraging sustained contributions of current Core Argo float groups with new and emerging Argo teams and users, can the OneArgo initiative be realised. This paper makes involvement with the Core Argo mission smoother by providing a framework endorsed by a wide community for these observations.

The ocean takes up approximately 25% of the carbon dioxide that humans emit to the atmosphere, it absorbs most of the excess heat trapped in the Earth system by greenhouse gas emissions, thus regulating climate and life on Earth, and also provides a remarkable number of resources for humanity. Most geo-hazards occur in oceanic areas. High-quality systematic ocean observations are necessary to improvour knowledge and understanding of the complex environmental processes and to serve as early warning systems of great socio-economic impact. Research Infrastructures (RIs) are large-scale facilities that provide resources and services for scientific communities to conduct high-level research and foster innovation. RIs promote knowledge, outreach and education to public, private, and policy stakeholders, as well as providing crucial information to operational services such as Copernicus. In Europe several marine RIs have been established, which are maintained by national and European Union (EU) resources. This paper describes the significance of the marine RIs in the European Marine Observation Landscape, their status in terms of cooperation, coordination and integration. It highlights the socio-economic benefits for this integration process, being a significant pillar of the European Ocean Observing System (EOOS)

The ocean regulates the exchange, storage of carbon dioxide, plays a key role in global control of Earth climate and life, absorbs most of the heat excess from greenhouse gas emissions and provides a remarkable number of resources for the human being. Most of the geo-hazards occur in oceanic areas. Thus, high-quality systematic observations are necessary tools for improving our understanding, and subsequent assimilation to provide early warning systems. A holistic scientific approach for the understanding of the ocean’s interrelated processes requires coordinated and complementary monitoring and observation programmes. Research Infrastructures (RIs) are large-scale facilities that provide resources and services for the scientific communities to conduct high-level research and foster innovation. RIs benefit from strong governance and multi-annual funding from their member states with operational life spans in decades. RIs promote knowledge, outreach and education to public, private, and policy stakeholders, and they play a key role in enabling and developing research in all scientific domains and currently represent a growing share of coordinated investment in research, and also in providing essential observations to operational services such as Copernicus. They are strategically important for Europe to lead a global movement towards a data-driven, interconnected, open digital twin that brings together different disciplines, clean technologies, public and private sectors and a broad scientific/technological community, as well as education and training. In Europe several marine RIs have been established, which are maintained by national and European Union (EU) resources. The aims of these infrastructures are aligned with the key priorities of the UN Decade of Ocean Science for Sustainable Development; and with the new European Research Area (ERA) Policy Agenda annexed to the Council conclusions on the ERA governance1, which set out 20 concrete actions for 2022-2024 to

Research Infrastructures (RIs) are large-scale facilities encompassing instruments, resources, data and services used by the scientific community to conduct high-level research in their respective fields. The development and integration of marine environmental RIs as European Research Vessel Operators [ERVO] (2020) is the response of the European Commission (EC) to global marine challenges through research, technological development and innovation. These infrastructures (EMSO ERIC, Euro-Argo ERIC, ICOS-ERIC Marine, LifeWatch ERIC, and EMBRC-ERIC) include specialized vessels, fixed-point monitoring systems, Lagrangian floats, test facilities, genomics observatories, bio-sensing, and Virtual Research Environments (VREs), among others. Marine ecosystems are vital for life on Earth. Global climate change is progressing rapidly, and geo-hazards, such as earthquakes, volcanic eruptions, and tsunamis, cause large losses of human life and have massive worldwide socio-economic impacts. Enhancing our marine environmental monitoring and prediction capabilities will increase our ability to respond adequately to major challenges and efficiently. Collaboration among European marine RIs aligns with and has contributed to the OceanObs’19 Conference statement and the objectives of the UN Decade of Ocean Science for Sustainable Development (2021–2030). This collaboration actively participates and supports concrete actions to increase the quality and quantity of more integrated and sustained observations in the ocean worldwide. From an innovation perspective, the next decade will increasingly count on marine RIs to support the development of new technologies and their validation in the field, increasing market uptake and produce a shift in observing capabilities and strategies.

Global Change is advancing rapidly making it urgent to strengthen our understanding of marine ecosystems vital for life on Earth. Geohazards such as earthquakes, eruptions, and tsunamis are ever-more frequent, resulting in great loss of life and massive damage to costly infrastructure, as we saw in the recent Fukushima nuclear plant disaster. Such drastic threats require quantum improvements to our understanding of the multiple and complex stress factors and forces that shape them. In this regard, the new breed of large environmental research infrastructures (RIs) being developed in various parts of the world are powerful tools. Of these, the 4 European marine RIs described below have assumed special leadership positions at the forefront of unprecedented new scientific and technological advances offering significant socio-economic benefits. These RIs are now transitioning to the next level, actively integrating and interconnecting their monitoring capabilities, greatly boosting our ability to respond effectively to the huge challenges posed to our oceans and world by Climate Change., Peer Reviewed, Postprint (published version)

Research Infrastructures (RIs) are large-scale facilities encompassing instruments, resources, data and services used by the scientific community to conduct high-level research in their respective fields. The development and integration of marine environmental RIs as European Research Vessel Operators [ERVO] (2020) is the response of the European Commission (EC) to global marine challenges through research, technological development and innovation. These infrastructures (EMSO ERIC, Euro-Argo ERIC, ICOS-ERIC Marine, LifeWatch ERIC, and EMBRC-ERIC) include specialized vessels, fixed-point monitoring systems, Lagrangian floats, test facilities, genomics observatories, bio-sensing, and Virtual Research Environments (VREs), among others. Marine ecosystems are vital for life on Earth. Global climate change is progressing rapidly, and geo-hazards, such as earthquakes, volcanic eruptions, and tsunamis, cause large losses of human life and have massive worldwide socio-economic impacts. Enhancing our marine environmental monitoring and prediction capabilities will increase our ability to respond adequately to major challenges and efficiently. Collaboration among European marine RIs aligns with and has contributed to the OceanObs’19 Conference statement and the objectives of the UN Decade of Ocean Science for Sustainable Development (2021–2030). This collaboration actively participates and supports concrete actions to increase the quality and quantity of more integrated and sustained observations in the ocean worldwide. From an innovation perspective, the next decade will increasingly count on marine RIs to support the development of new technologies and their validation in the field, increasing market uptake and produce a shift in observing capabilities and strategies

Glider measurements acquired along 4 transects between Cap‐Vert Peninsula and the Cape Verde archipelago in the eastern tropical North Atlantic during March‐April 2014 were used to investigate fine‐scale stirring in an anticyclonic eddy. The anticyclone was formed near 12°N off the continental shelf and propagated north‐west towards the Cape Verde islands. At depth, between 100‐400 m, the isolated anticyclone core contained relatively oxygenated, low salinity South Atlantic Central Water, while the surrounding water masses were saltier and poorly oxygenated. The dynamical and thermohaline subsurface environment favored the generation of fine‐scale horizontal and vertical temperature and salinity structures in and around the core of the anticyclone. These features exhibited horizontal scales of O(10‐30 km) relatively small with respect to the eddy radius of O(150 km). The vertical scales of O(5‐100 m) were associated to density‐compensated gradient. Spectra of salinity and oxygen along isopycnals revealed a slope of around k‐2 in the 10‐100 km horizontal scale range. Further analyses suggest that the fine‐scale structures are likely related to tracer stirring processes. Such mesoscale anticyclonic eddies and the embedded fine‐scale tracers in and around them could play a major role in the transport of South Atlantic Central Water masses and ventilation of the North Atlantic Oxygen Minimum Zone.

A method to estimate mass and heat transports across hydrographic sections using hydrography together with altimetry data in a geostrophic box inverse model is presented. Absolute surface velocities computed from AVISO altimetry products made up of a combination of sea surface height measurements and geoid estimate are first compared to Ship Acoustic Doppler Current Profiler (S-ADCP) measurements of the Ovide project along hydrographic sections repeated every 2 years in summer from Portugal to Greenland. The rms difference between S-ADCP and altimetry velocities averaged on distances of about a hundred km accounts to 3.3 cm s−1. Considering that the uncertainty of S-ADCP velocities is found at 1.5 cm s−1, altimetry errors are estimated at 3 cm s−1. Transports across Ovide sections previously obtained using S-ADCP data to constrain the geostrophic inverse box model are used as reference. The new method is found useful to estimate absolute transports across the sections, as well as part of their variability. Despite associated uncertainties about 50% larger than when S-ADCP is used, our results for the North Atlantic Current and heat transports, with uncertainties of 10 to 15%, reproduce the variability already observed. The largest uncertainties are found in the estimates of the East Greenland Irminger Current (EGIC) transport (30%), induced by larger uncertainties associated with altimetry data at the western boundary.

[1] In earlier studies, the decadal variability of the Deep Western Boundary Current (DWBC) transport in the vicinity of Cape Farewell, Greenland, has been assessed from changes in the baroclinic velocities computed from hydrographic data and referenced to 1000 m depth. The main limitation of using such an estimate as an index for the DWBC absolute transport variability comes from the unaccounted for decadal velocity changes at the reference level (1000 m). These changes may substantially contribute to the DWBC absolute transport variability by compensating for or adding to the baroclinic transport changes. To assess this contribution to variability, we quantify the decadal velocity changes which occurred at 1000 m depth southeast of Cape Farewell since the mid-1990s. The analysis combines estimates of the baroclinic velocity changes in the water column derived from repeat hydrography at similar to 59.5 degrees N and the velocity changes at the sea surface derived from altimetry. An increase in the southward velocity at 1000 m above the DWBC between the periods of 1994-1997 and 2000-2007 is inferred. It indicates that the increase in the DWBC absolute transport was larger than the 2 Sv (1 Sv = 10(6) m(3) s(-1)) increase in its baroclinic component referenced to 1000 m. This result and the observed coherence of the DWBC absolute and baroclinic transport changes between individual observations imply that the DWBC absolute transport variability in the region is underestimated but qualitatively well represented by its baroclinic component on decadal and shorter time scales.

Chlorofluorocarbon (CFC) 11 and 12 transports across the transoceanic World Ocean Circulation Experiment (WOCE) A25 section in the subpolarNorthAtlantic are derived from an inverse model using hydrographic and ADCP data (Lherminier et al., 2007). CFC and anthropogeniccarbon (CANT) advective transports contrary to expected are uncoupled: CANT is transported northeastwards (82±39 kmol s−1) mainly within the overturning circulation, while CFC-11 and CFC-12 are transported southwestwards (−24±4 and −11±2 mol s−1, respectively) as part of the large-scale horizontal circulation. The main reason for this uncoupled behaviour is the complex CFC vs. CANT relation in the ocean, which stems from the contrasting temperature relation for both tracers: more CANT dissolves in warmer waters with a low Revelle factor, while CFC’s solubility is higher in cold waters. These results point to CANT and CFC having different routes of uptake, accumulation and transport within the ocean, and hence: CANTtransport would be more sensitive to changes in the overturning circulation strength, while CFC to changes in the East Greenland Current and Labrador Sea Water formation in the Irminger Sea. Additionally, CANT and CFCs would have different sensitivities to circulation and climate changes derived from global warming as the slowdown of the overturning circulation, increase stratification due to warming and changes in wind stress.

The first Ovide cruise occurred in June–July 2002 on R/V Thalassa between Greenland and Portugal. The absolute transports across the Ovide line are estimated using a box inverse model constrained by direct acoustic Doppler current profiler velocity measurements and by an overall mass balance (±3 Sv, where 1 Sv = 106 m3 s 1) across the section. Main currents are studied and compared to the results of the similar Fourex section performed in August 1997 and revisited here. The meridional overturning cell (MOC) is estimated in two different ways, both leading to a significantly lower value in June 2002 than in August 1997, consistent with the relative strength of the main components of the MOC (North Atlantic Current and deep western boundary current). It has been found that the MOC calculated on density levels is more robust and meaningful than when calculated on depth levels, and it is found to be 16.9 ± 1.0 Sv in 2002 versus 19.2 ± 0.9 Sv in 1997. The 2002 heat transport of 0.44 ± 0.04 1015 W is also significantly different from the 0.66 ± 0.05 1015 W found in 1997, but it is consistent with the much weaker integrated warm water transport across the section than in 1997.

Numerical models are used to estimate the meridional overturning and transports along the paths of two hydrographic cruises, carried out in 1997 and 2002 from Greenland to Portugal. We have examined the influence of the different paths of the two cruises and found that it could explain 0.4 to 2 Sv of difference in overturning (the precise value is model-dependent). Models show a decrease in the overturning circulation between 1997 and 2002, with different amplitudes. The CLIPPER ATL6 model reproduces well the observed weakening of the overturning in density coordinates between the cruises; in the model, the change is due to the combination of interannual and high-frequency forcing and internal variability associated with eddies and meanders. Examination of the z-coordinate overturning reveals model-data discrepancies: the vertical structure in the models does not change as much as the observed one. The East Greenland current variability is mainly wind-forced in the ATL6 model, while fluctuations due to eddies and instabilities explain a large part of the North Atlantic Current variability. The time-residual transport of dense water and heat due to eddy correlations between currents and properties is small across this section, which is normal to the direction of the main current.