The distribution of water masses and their characteristics, including ventilation, provides fundamental insights into large-scale oceanographic processes such as thermohaline circulation and marine biogeochemical cycles. The characteristics of main water masses in the Atlantic Ocean have been comprehensively documented in a companion study (Liu and Tanhua, 2021); this study presents quantitative assessments of water mass age c...

The deep waters of the Gulf of St. Lawrence (GSL) have experienced a significant reduction in dissolved oxygen content during the past decades. One widely documented driver of this deoxygenation is a change in the composition of the deep inflowing water that ventilates the Gulf, which consists of a mixture of warmer, less-oxygenated North Atlantic Central Waters (NACW) and cooler, more-oxygenated Labrador Current Waters (LCW)....

The need for ocean information has never been greater. From climate change to food security and extreme events, we need to understand the role of the ocean and better predict change and impact. This is only possible with the sustained collection of a key set of ocean observations. The Global Ocean Observing System (GOOS) coordinates international efforts to collect these Essential Ocean Variables (EOVs), which span physics, bi...

The Arctic Ocean is changing rapidly and Atlantic Water circulation plays a key role in the warming, sea-ice decline, and ecosystem changes observed in the Arctic. Still, we only have limited understanding of the pathways and circulation times of Atlantic-derived water both at surface and mid-depth layers in the Arctic Ocean, and their evolution over time. Here, we investigate the water mass composition and circulation in the...

The Gulf and Lower St. Lawrence Estuary have experienced major environmental change over the past century, including the development of hypoxic bottom waters and their simultaneous warming and acidification. Here, we use biogeochemical observations collected during the 2021–2023 TReX project as well as historical data, integrated with a tracer-calibrated 1D Advection-Diffusion model with variable boundary conditions to represe...

The European Ocean Observing Community (EOOC) integrates inputs from diverse entities dedicated to comprehensively monitoring and forecasting oceanic phenomena in European Seas. With increasing climate and anthropogenic pressures, the urgency of ensuring the EOOC’s preparedness to observe Essential Ocean Variables (EOVs) is evident. This paper advocates for the adoption of a scoring approach designed to evaluate the readiness...

This study investigates the spatial and temporal distribution of the artificial radionuclides 129I and 236U in the Western Mediterranean Sea, focusing on their connection to radionuclide sources and circulation dynamics. Taking advantage of unprecedented precision of accelerator mass spectrometry, both tracers were firstly investigated in 2013. Here, we examine tracer observations obtained along four stations (re-)visited duri...

The EU funded project EuroSea brought together key actors of the European ocean observing and forecasting communities with key users of the ocean observing products and services in order to better integrate existing ocean observation systems and tools, and to improve the delivery of ocean information to users. EuroSea was constructed around the ocean observing value chain that connects observations to users of ocean informatio...

The interdisciplinary community of ocean and coastal observers and modelers in Europe is driven by national observing needs for prediction and management of intricate processes shaping Europe’s Seas. Not all observing needs can be addressed by nations alone and various coordination activities exist to overcome fragmentation and create cross benefit within the European Ocean Observing Community (EOOC). This way critical insight...

Ocean deoxygenation and expansion and intensification of hypoxia in the ocean are a major, growing threat to marine ecosystems. Measures currently used to protect marine biodiversity (e.g., marine protected areas) are ineffective in countering this threat. Here, we highlight the example of the Gulf of St. Lawrence in eastern Canada, where oxygen loss is not only due to eutrophication (which can be mitigated by nutrient control...

Ocean data synthesis products for specific biogeochemical essential ocean variables have the potential to facilitate today’s biogeochemical ocean data usage and comply with the Findable Accessible Interoperable and Reusable (FAIR) data principles. The products constitute key outputs from the Global Ocean Observation System, laying the observational foundation for information and services regarding climate and environmental sta...

Assessing the status of ocean acidification across ocean and coastal waters requires standardized procedures at all levels of data collection, dissemination, and analysis. Standardized procedures for assuring quality and accessibility of ocean carbonate chemistry data are largely established, but a common set of best practices for ocean acidification trend analysis is needed to enable global time series comparisons, establish...

Understanding and sustainably managing complex environments such as marine ecosystems benefits from an integrated approach to ensure that information about all relevant components and their interactions at multiple and nested spatiotemporal scales are considered. This information is based on a wide range of ocean observations using different systems and approaches. An integrated approach thus requires effective collaboration b...

Effective data management plays a key role in oceanographic research as cruise-based data, collected from different laboratories and expeditions, are commonly compiled to investigate regional to global oceanographic processes. Here we describe new and updated best practice data standards for discrete chemical oceanographic observations, specifically those dealing with column header abbreviations, quality control flags, missing...

In this paper, we outline the need for a coordinated international effort toward the building of an open-access Global Ocean Oxygen Database and ATlas (GO 2 DAT) complying with the FAIR principles (Findable, Accessible, Interoperable, and Reusable). GO 2 DAT will combine data from the coastal and open ocean, as measured by the chemical Winkler titration method or by sensors (e.g., optodes, electrodes) from Eulerian and Lagrang...

From 2008 to 2019, a comprehensive research project, ‘SFB 754, Climate – Biogeochemistry Interactions in the Tropical Ocean,’ was funded by the German Research Foundation to investigate the climate-biogeochemistry interactions in the tropical ocean with a particular emphasis on the processes determining the oxygen distribution. During three 4-year long funding phases, a consortium of more than 150 scientists conducted or parti...

This study evaluates the potential usefulness of the halogenated compounds HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14, and PFC-116 as oceanographic transient tracers to better constrain ocean ventilation processes. We do this mainly in terms of four aspects of the characteristics of the potential tracers: input function (including atmospheric history and historical surface saturation), seawater solubility...

A large number of water masses are presented in the Atlantic Ocean, and knowledge of their distributions and properties is important for understanding and monitoring of a range of oceanographic phenomena. The characteristics and distributions of water masses in biogeochemical space are useful for, in particular, chemical and biological oceanography to understand the origin and mixing history of water samples. Here, we define t...