Ekman's (1905) solution for how wind affects ocean surface currents is revisited and extended analytically for a piecewise-constant profile of vertical diffusion. This allows a comprehensive understanding of how the surface current deflection angle relative to the wind direction varies with the profile of vertical diffusion.

Because the density of seawater depends on both temperature (T) and salinity (S), it is possible for seawater samples of the same density to have possibly widely different T/S characteristics, ranging from hot and salt (spicy) to fresh and cold (minty). For several decades, oceanographers have been debating about how best to construct a variable for quantifying the spiciness of seawater. This work discusses the relative merits/drawbacks of existing approaches and proposes a new way forward.

The mixing of water masses into the deep ocean in the North Atlantic is important for the entire global ocean circulation. We use seven global climate models to investigate the effect of increasing the model resolution on this deep ocean mixing. The main result is that increased model resolution leads to a deeper mixing of water masses in the Labrador Sea but has less effect in the Greenland Sea. However, most of the models overestimate the deep ocean mixing compared to observations.

This paper proposes a new algorithm called AFTER-SSIM algorithm to evaluate the performance of 101 selected global climate models under different emission scenarios during 2006 to 2018 and reduces the uncertainty among them.  AFTER-SSIM algorithm shows good performance in sea ice combined forecast and uncertainty reduction among global climate models. The possibility beyond 80 % indicates that the Arctic Northern Sea Route will be open to 1A super vessels for 5 months in the year of 2030.

The Earth System Models in the CMIP5 are widely used to study climate change, so the accuracy of models should be evaluated in key areas such as the North Atlantic where the relationship between the winter sea surface temperature (SST) and the North Atlantic Oscillation (NAO) is very important. Our results show that the link between the SST and the NAO-driven turbulent heat fluxes cannot be well simulated by most models, leading to that models cannot reproduce the observed NAO–SST relationship.

Currents are high-speed continuous ocean flows. In general, currents accelerate the surface waves. However, studies were performed at normal wind speeds only, and few studies at extreme high wind speeds. Thus, we investigate the effects of current on surface waves at extreme high wind speeds. We used three wind-wave tanks to demonstrate surface waves and currents. As a result, at extreme high wind speeds, a similar acceleration effect is observed as under the conditions of normal wind speeds.

Study of long-term changes in extreme waves and in the synoptic patterns related to them, in the European coasts. Being controlled the interannual variability of extreme waves in the North Atlantic Ocean by the atmospheric patterns of North Atlantic Oscillation and Scandinavian indices. And in the Mediterranean Sea, they are governed by the East Atlantic and East Atlantic/Western Russia modes, acting strongly during their negative phases.

We investigated the evolution of anthropogenic CO₂ (C_ant) in the Antarctic Bottom Water in the Southern Indian Ocean since 1978 based on observations from 16 reocupations. We found that the Cant and the dissolved inorganic carbon increased at about the same rate over the 40-years period. However, the data also show large interannual variations and a surprising stability of C_ant in the last decade likely reflecting the variability of bottom waters formations and circulation in the Southern Ocean.

In 2016 and 2017, an open-water area emerged within the Antarctic sea-ice pack, the so-called Maud Rise polynya. The opening of the sea ice has been linked to intense winter storms. In this study, we investigate another important contributor to polynya formation by analysing subsurface static instabilities. These static instabilities initiate subsurface convection near Maud Rise. We conclude that apart from winter storms, subsurface convection plays an important role in polynya formation.

This study investigates the impact of the uncertainty in atmospheric data of a storm event on the transport of microplastics and sediments. The model chain includes the atmospheric model WRF, the wave model WAVEWATCH III® and the regional ocean model GETM together with a sediment transport model based on the FABM framework. An ensemble approach based on stochastic perturbations of the WRF model is used. We found a strong impact of atmospheric uncertainty on the amount of transported material.

A kilometre-scale coupled ocean–atmosphere simulation is used to study the impact of a medicane on the oceanic upper layer. The processes responsible of the surface cooling are comparable to those of weak tropical cyclones, with a dominant effect of the surface forcing. The oceanic response is influenced by the dynamics of Central Mediterranean. In particular, a cyclonic eddy leads to weaker cooling. Heavy rain occuring early in the event create a salinity barrier layer, weakening the turbulent.

Global inorganic and organic nutrient deposition fields are coupled to PISCES to investigate their effect on ocean biogeochemistry. Preindustrial deposition fluxes are lower compared to present-day, resulting in lower oceanic productivity. Future changes result in a modest decrease in the nutrients input into the global ocean. This work provides a first assessment of the atmospheric organic nutrients' contribution, highlighting the importance of their representation in biogeochemistry models.

In the equatorial Pacific, air–sea CO₂ flux is known to fluctuate in response to inherent climate variability, predominantly the El Niño–Southern Oscillation. In this study, the same data assimilation scheme is incorporated into two Earth system models and fluctuations of air–sea CO₂ flux in the equatorial Pacific were evaluated. Our results demonstrate that adequate simulation of El Niño–Southern Oscillation is crucial for accurate reproduction of the variability in air–sea CO₂ flux.

Based on a well-validated ocean circulation model, we found that near-inertial oscillations (NIOs) and near-inertial kinetic energy (KEni) varied distinctly during forcing and relaxation stages of the TC forcing, and the horizontal and vertical transport of KEni was largely modulated by the velocity and vorticity of the jet stream in the semi-enclosed South China Sea (SCS). This study enriches our understanding of the spatial-temporal variability of NIOs in the frequently TC-affected SCS.

During the mid-1970 and quite recently in 2017, a large open-water area appeared in the Antarctic sea ice pack, the so-called Maud Rise polynya. From several model studies, the re-occurrence time of this polynya seems arbitrary. In this study, we address the re-occurrence time of the polynya using a high-resolution climate model. We find a preferred multidecadal return time in polynya formation. The return time of the polynya is associated with a large-scale ocean mode in the Southern Ocean.

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 very well observed variability in coastal sea level and GS flow on time scales between ~ 5–50 years.

High-resolution ocean models ROMS and FESOM configured for the Fram Strait reveal very turbulent ocean conditions there. The two main currents meander strongly, and shed circular currents of water, called eddies. Our analysis shows that this region is characterised by small and short living eddies (on average around 5 km radius and 10 days lifetime). Both models agree on eddy properties and show similar patterns of baroclinic and barotropic instability of the West Spitsbergen Current.

Bardsey Island lies 3 km offshore the western end of the Llŷn Peninsula in north-west Wales. But the island is too small to show up in tidal databases based on satellite data, so they may not provide the correct local tides. Our new sea-level data from the area shows that the tidal currents in the satellite databases are 1/3 of the observed. Any investigation of other coastal activities, e.g., renewable energy installations, must use local observations to get the correct tides.

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 25–40 % 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.