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.

Forecasts of ocean temperature, salinity, currents and sea height can be improved by linking state-of-the-art ocean and wave models, so that they can interact to better represent the real world. We test this approach in an ocean model of north-west Europe which can simulate small-scale details of the ocean state. The intention is to implement the system described in this study for operational use so that improved information can be provided to users of ocean forecast data.

The main goals are to study the performance of gridded SST datasets in the coastal waters by comparing to the homogenized in situ SST records. In recognizing that local data may reflect local effects, we focus on dominant EOFs of the in situ SSTs and localized gridded datasets, examining patterns, variabilities and trends. We conclude that gridded datasets need improvement in the pre-satellite time, by re-examining in detail archives of local SST records in many data-sparse regions.

The pelagic in situ observation system (PELAGIOS) is a new towed observation system with HD video camera and environmental sensors. It is used for pelagic video transects down to 3000 m. The system enables the visualization and exploration of pelagic organisms (> 1 cm), in particular delicate gelatinous fauna, that cannot be captured by nets. The video and hydrographic data gives insight in the biodiversity, abundance and distribution of oceanic pelagic organisms, from the surface to the deep sea.

We revisit the sources for the upper limb of the overturning circulation in the South Atlantic by tracking fluid particles in a high-resolution ocean model. Our results suggest that the upper limb’s transport is dominantly supplied by waters with Indian Ocean origin, but the contribution of waters with Pacific origin is substantially larger than previously estimated with coarse-resolution models. Yet, a large part of upper limb waters get their thermohaline properties within the South Atlantic.

This study shows how the Mississippi river influenced the spreading of oil in the Gulf of Mexico after the DeepWater Horizon disaster. High resolution numerical models for ocean and atmosphere circulation are used to force an oil drift model. The circulation is totally different when river input is removed in the ocean model. The study also showcase the importance of the choice of oil droplet size distribution. Model output is compared with satellite observation of surface oil.

To better exploit the observational information available for all scales in data assimilation systems, we investigate a new method to introduce scale separation in the algorithm. It consists in carrying out the analysis with spectral localisation for the large scales and spatial localisation for the residual scales. The performance is then checked explicitly and separately for all scales. Results show that accuracy can be improved for the large scales while preserving reliability at all scales.

The paper presents a correlation that can potentially improve the signal obtained from ocean color remote sensing. Results come from a modelling applied to the atmosphere-ocean system in different regions of the southern Baltic, two seasons, and two wind speeds, each for nine visible spectral bands. The results show that the variability of the maximum of DoP depends more on seasonal than regional changes and can be explained to a large degree by the seawater absorption-to-attenuation ratio.

Sea surface temperature (SST) is related to ocean heat content, an important topic in the debate over global warming. In this manuscript, we propose a novel SST predicting method based on the hybrid improved EMD algorithms and BP neural network method. SST prediction results based on the hybrid EEMD-BPNN and CEEMD-BPNN models are compared and discussed. Cases study of SST in the North Pacific shows that the proposed hybrid CEEMD-BPNN model can effectively predict the time-series SST.

We analyse how surface drifters separate when being released as pairs or triplets in close proximity to wind farms. There is some tentative evidence that these drifters experience turbulent flows arising from an interaction between tidal currents and wind turbine towers. However, more comprehensive studies would be needed to clearly distinguish such wind farm related effects from the effects of turbulence that naturally occurs in a complex coastal environment.