In the North Atlantic, ocean currents transport warm waters northward in the upper water column, and cold waters southwards at depth. This circulation, not easily measured in situ, is here obtained from surface data and thermodynamics theory. Its driving role in recent temperature changes (1993–2017) in the North Atlantic is evidenced, and predictions of near-future variability (5 years) are provided and discussed.

In this paper we present a gas equilibrator that can be used to extract gases continuously or in discrete samples from seawater. The head space is analysed by a commercially available Proton Transfer Reaction - Mass Spectrometer. This allows measurement of a broad range of dissolved gases up to a very high solubility in seawater. The main advantage of this equilibrator lies in it's unique design and ease of reproducibility.

The present study describes the surface distribution of the partial pressure of CO₂ in the continental shelf of the eastern Gulf of Cádiz. For this, eight oceanographic cruises were carried out between March 2014 and February 2016. This distribution presents a linear dependence with the temperature and it decreases with distance from the coast. The Gulf of Cádiz acts as a sink of CO₂ with a mean value for the study period of −0.18 ± 20 1.32 mmol m⁻² d⁻¹.

This work highlights the relevance of coupling wave model with ocean model in order to improve key surface ocean parameters and in general to better describe the ocean circulation at small and large scale. The results focus on the Iberian Biscay and Ireland ocean region with fine grid resolution of 2.5 km for the ocean model. The main conclusion is the improvement of wave physics induces a better ocean mixing at the upper layer and a positive impact for sea surface height in storm events.

This study is focused on water exchange between the Sea of Azov and the Black Sea. The Sea of Azov is a small and freshened sea that receives a large freshwater discharge and, therefore, can be regarded as a large river estuary connected by narrow Kerch Strait with the Black Sea. In this work we show that water transport through the Kerch Strait is governed by wind forcing and do not show dependence on river discharge rate to the Sea of Azov on intra-annual time scale.

A new high resolution ocean model at 1.5 km has replaced the 7 km system for delivering short term forecasts of the North-West European shelf Seas. The products, temperature, salinity, currents, sea surface height, are available on the Copernicus Marine Service catalogue. This study is focus on the high resolution impact on the quality of the products delivered to the users. Results show that the high resolution model is better resolving the variability of the physical variables.

Estuaries are areas where riverine and oceanic waters meet and mix. The exchange flow of an estuary describes the water properties of the inflowing and outflowing water. These can be described by simple bulk values for volume fluxes and salinities. This work focuses on the numerics of one computational method for these values, the Total Exchange Flow. We show that only the so called dividing salinity method is able to reliably calculate the correct values, even for complex situations.

Highlights: Documented role of oceanic cyclonic eddies in modifying track and life cycle of cyclone by way of abrupt track reversal and rapid decay. Cyclone-induced increase in the chlorophyll a biomass ranged from 5 to 7 fold, while the net primary productivity from 2.5 to 8 fold. A 3.7 fold increase in cyclone-induced CO₂ out-gassing indicative of the altering regional CO₂ balance in the BoB, which is a weak sink.

The assimilation of satellite SST data into ocean models is complex. The temperature of the thin uppermost layer that is measured by satellites may differ from the much thicker upper layer used in numerical models, leading to biased results. This paper shows how canonical correlation analysis can be used to generate observation operators from existing datasets of model states and corresponding observation values. This type of operator can correct for near-surface effects when assimilating SST.

In this study we investigated the variability of the Arctic Front (AF), an important biologically productive region in the Norwegian Sea, using a suite of satellite data, atmospheric reanalysis and a regional coupled ocean-sea ice data assimilation system. We show evidences of the two-way interaction between the atmosphere and the ocean at the AF. The North Atlantic Oscillation is found to influence the strength of the AF and may have a profound influence on the region’s biological productivity.

The sandy seafloor in shelf seas is constantly overturned by waves and currents but also by a large number of animals searching for shelter and food. By taking a close look at the seafloor surface with the help of a laser scanner, this study evaluates their contribution to the overall reworking of sediment: It makes up as much as 14 % of the physically driven reworking. The activity of the organisms varies with the seasons and between different locations and can be estimated from physical values.

Focused on the Arctic sea surface salinity (SSS), two gridded SMOS products, two CMEMS reanalyzed products, and two climatologies (PHC and WOA) are evaluated by intercomparison and against in-situ data during the years of 2011–2013. The quantitative SSS evaluation also sheds light on the uncertainty analyzing of the different products, which also give useful information needed for the assimilation of the SMOS SSS products into ocean forecast/reanalysis systems at next.

As part of the Copernicus Marine Environment Monitoring Service, an operational ocean forecasting system monitors the ocean dynamics and marine ecosystems of the European waters. This paper assesses the performances of the key biogeochemical variables (oxygen, nutrients, chl-a, primary production), using a 7-year retrospective simulation (2010–2016). The simulation can be used to better understand the current state, the changes and the health of European marine ecosystems.

A statistical-dynamical observation operator (SOSSTA) for satellite SST data assimilation able to account for SST diurnal variability, is formulated and implemented into the POSEIDON forecasting system (Aegean Sea). Model experiments where daytime SST retrievals from the SEVIRI infrared radiometer are introduced into the data assimilation procedure through the application of the observation operator, showed an improvement of the POSEIDON modelling system performance.

This paper describes the differences between ocean surface winds provided by ERA reanalyses and satellite scatterometer observations. This work is motivated by the widespread use of reanalysis winds for ocean forcing in marine forecasting centers, and the application of scatterometer observations as a means to characterize reanalysis wind errors, which we conjecture are related to deficiencies in the physics of the underlying assimilating model.

Coupled atmosphere-ocean modelling systems allow changes in the ocean to directly and immediately feed back on the atmosphere and enable improved weather prediction and ocean forecasts. This is particularly true if the coupled feedbacks are also considered in the way real-time observations of the atmospheric and oceanic states are used to obtain the initial conditions for the forecasts. Here we demonstrate promising performance from such a coupled system when used for ocean prediction.

The Mediterranean Outflow Water (MOW) is a dense water mass originated in the Gibraltar Straight. The CMEMS IBI ocean reanalysis is used to provide a detailed view of the circulation and mixing processes of MOW near the Iberian and African Continental slopes. This work emphasizes the relevance of the complex bathymetric features defining the circulation and variability processes of MOW in this region.

Ocean and sea-ice reanalysis is valuable data with broad applications. This manuscript is a reference document for the ECMWF ocean and sea-ice ensemble analysis system OCEAN5, and historical reanalysis ORAS5. Description of the system and assessment of ORAS5 in the sense of several key ECVs have been documented here. This data set is particularly important for users with interest on studying, e.g., Climate Change Indicators, ocean state/environment monitoring, NWP initialization and validation.

This paper deals with sea level altimeter products. These geophysical data are distributed as along-track and gridded data through Copernicus program CMEMS and C3S. We present here in detail a new reprocessing of the data (DT2018) from 1993 to 2017. The main changes and their impacts since last version (DT2014) are carefully discussed. This comparison is made using independent dataset. DT2018 sea level products are improved at global and regional scale and especially in coastal areas.

In this study we assessed the impacts of the world’s largest dam, Three Gorges Dam (TGD), on tide-river dynamics and concluded that the strongest impacts occurred during autumn and winter owing to the TGD's operation. The results obtained will, hopefully, enhance our understanding of the impacts of large-scale human interventions on estuarine hydrodynamics and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.

This is the first investigation of the worldwide distribution of the degree-3 M1 ocean tide using over 800 tide gauge records and a global tide model. M1 is confirmed to have a geographical variation in the Atlantic and other basins consistent with the suggestion of Platzman and Cartwright that M1 is generated through the spatial and temporal overlap of M1 in the tidal potential and one (or at least a small number) of diurnal ocean normal modes.

This study investigates the resolving capabilities of the DUACS gridded products delivered through the CMEMS catalogue. Our method is based on the spectral coherence. While altimeter along-track resolves scales in the order of few tens of kilometers, we found that the merging of these along-track data into continuous maps in time and space leads to effective resolution ranging from ~ 800 km wavelength at the Equator to 100 km wavelength at high latitude.

Oceans are modified at the surface by winds and by exchange of heat with the atmosphere. The effect of changing information about the atmosphere that is available to drive an ocean model of north-west Europe, which can simulate small-scale details of the ocean state, is tested. We show that simulated temperatures agree better with observations located near the coast around south-west UK when using data from a high resolution atmosphere model, and when atmosphere and ocean feedbacks are included.

Simplified 2DH numerical models are typically used for simulating the transport of floating microplastics. This paper demonstrates the impact of vertical mixing on the horizontal transport and fate of microplastics in a bay, and therefore the importance of a 3D approach for an accurate modelling of microplastics transport. These results have important implications for the assessment and prediction of pollution hot spots in coastal systems, as well as for planning effective clean-up programs.

Retreating sea ice in the Arctic Ocean gives rise to increased naval traffic with shorter navigation distances. Hence, information about the position of the sea ice edge is crucial for safe navigation. In the present study we explore methods for examining the quality of sea ice edge forecasts. We conclude that the forecast quality can be monitored with results from a set of four quantities. We also recommend the use of maps which display discrepancies in the positions of the sea ice edge.

In a large-scale analysis, the spread of disinfection by-products from oxidative ballast water treatment is investigated, with focus on Southeast Asia where major ports are located. Especially halogenated compounds such as bromoform (CHBr₃) are produced in the ballast water and once emitted into the environment can participate in ozone depletion. Anthropogenic bromoform is rapidly emitted to the atmosphere and can locally double around large ports. A large-scale impact cannot be found.