The bottom water of the northern Baltic Sea usually is well oxygenated. We used a combined approach of numerical model simulations and in situ observations to investigate processes responsible for a regular ventilation of the Bothnian Bay. Surface water masses from the Bothnian Sea and the Bothnian Bay mix at the link between both regions. In winter, when water temperature is low, the resulting density is large enough that the water descends and replaces old bottom water.

The Yenisei and Khatanga rivers are among the largest estuarine rivers that inflow to the Arctic Ocean. Discharge of the Yenisei River is 1 order of magnitude larger than that of the Khatanga River. However, spatial scales of buoyant plumes formed by freshwater runoff from the Yenisei and Khatanga gulfs are similar. This feature is caused by intense tidal mixing in the Khatanga Gulf, which causes formation of the diluted and therefore anomalously deep and large Khatanga plume.

River plume characteristics (density, velocity, turbulence) are measured in the first several kilometers of a river flow entering a New Zealand fjord. These observations are used to quantify the influence of the main plume dynamics on controlling the behavior and structure of the flow. The mixing of dense, stationary water from below into the fast-flowing plume drove its deceleration. Internal waves were capable of transporting almost 15 % of the total momentum out beyond the plume's boundaries.

An analytical method combining electro-dialysis with high-performance anionic exchange chromatography coupled to pulsed amperometric detection was developed and optimized for analyzing free and combined carbohydrates in seawater and other saline environmental samples.

We assessed the potential benefit of a new verification metric, developed by the atmospheric community, to assess high-resolution ocean models against coarser-resolution configurations. Typical verification metrics often do not show any benefit when high-resolution models are compared to lower-resolution configurations. The new metric showed improvements in higher-resolution models away from the grid scale. The technique can be applied to both deterministic and ensemble forecasts.

As direct measurements of seawater carbonate system variables, such as pH, are difficult to obtain, scientists use equilibrium constants to compute them from known variables. Using a compilation of in situ data, we show that the set of equilibrium constants preferred by the community is not consistent with measurements in cold, polar waters, where human-made ocean acidification is spreading rapidly. Closing knowledge gaps regarding seawater carbon chemistry in polar regions should be a priority.

The RAPID 26° N array has been measuring the Atlantic meridional overturning circulation (AMOC) since 2004. Since 2009 the AMOC has, compared with previous years, been in a low state. In 2013–2015, in the northern North Atlantic, strong cooling was observed in the ocean and anticipated to intensify the strength of the AMOC some years later. Here, we analyse the latest results from 26° N and conclude that while the AMOC has increased since 2009, this increase is not statistically significant.

Satellite observations of the ocean were combined with a numerical model to create simulations of the ocean state between 1998 and 2010. Relationships between physical and biogeochemical quantities were assessed to investigate whether observations of different variables are consistent in their representation of the Earth system. Good consistency was found. The results also highlighted ways in which the model could be improved and the respective impacts of using different observations.

Ocean profiling observation in the Indian Ocean is not sufficient. We conducted a hydrographic survey on the Carlsberg Ridge, which is a mid-ocean ridge in the northwest Indian Ocean, to obtain snapshots of sectional temperature, salinity, and density fields by combining the ARGO data. The results show mesoscale eddies located along the specific ridge and the existence of a west-propagating planetary wave. The results provide references in the regional ocean circulation.

This study examines the accumulation of microplastics on wild and cultured mussels through a dynamic energy budget model, resulting in a comparable contamination level but different cleaning time for the mussels. Our main findings highlight that microplastics contamination is strongly dependent on the variability of specific environmental aspects and improve the knowledge of the transport and accumulation of microplastics in the mussels, enlightening future work on a biomagnification scenario.

We analyzed changes in wind patterns during the last 70 years (1948–2017) in the Canary Current area, located in one of the major upwelling regions in the world, using monthly NCEP wind data. Results demonstrate that trade winds were quite stable in direction but suffered a significant net decrease of 1 m s⁻¹ in intensity. We also found significant correlations between the NAO index and the wind direction and intensity, specifically in winter, and between the AMO index and the wind direction.

Common ways of describing the rise and fall of the tides are essential for safe, productive coastal habitation. We have long had a useful formula to describe the rise and fall of tides at daily timescales but no purposive method for characterising tidal height variations at longer timescales. This paper uses observations from New Zealand, plus model data, to explain the different tidal envelope types evident at monthly timescales, complementing the existing way of describing daily tidal forms.

The oceans play an important role in moving heat between the equatorial and polar regions, with both large current systems and smaller eddies contributing to this heat transport. This analysis separates the contribution of the larger-scale and eddy-scale flows in the North Atlantic, finding that eddy-scale flows account for 25–35 % of the heat transport in middle latitudes near 40° N. The study also shows how the year-to-year variability of eddies contributes to heat transport changes at 40° N.

Regional variability and changes in ocean dynamics during 1900–2015 were obtained in the western North Atlantic Ocean from a global sea level reconstruction. An unprecedented long period of weakening in the Gulf Stream (GS) flow since the late 1990s was found. The variability and slowdown of the GS were related to the Atlantic Meridional Overturning Circulation. The reconstruction captured observed variability in the coastal sea level and GS flow on timescales of ∼5–50 years very well.