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

We analyse the intraseasonal variability of the alongshore circulation off Peru in early 2017, this circulation is very important for the supply of nutrients to the upwelling regime. The causes of this variability and its impact on the biogeochemistry are investigated. The poleward flow is strengthened during the observed time period, likely by a downwelling coastal trapped wave. The stronger current causes an increase in nitrate and reduces the deficit of fixed nitrogen relative to phosphorus.

Seismic oceanography acquires water column reflections by seismic exploration. The use of a high-frequency seismic source such as sparker can enhance the resolution of reflection image but suffers from a low signal-to-noise ratio problem. In this study, we applied a machine learning to remove the random noise in water column seismic section. We constructed appropriate training data and showed that the machine learning can successfully remove the random noise in the water column seismic section.

This is a study of long-term changes in extreme waves and in the synoptic patterns related to them on European coasts. The interannual variability of extreme waves in the North Atlantic Ocean is controlled by the atmospheric patterns of the North Atlantic Oscillation and Scandinavian indices. In the Mediterranean Sea, it is governed by the East Atlantic and East Atlantic/Western Russia modes acting strongly during their negative phases.

With present-day techniques, ocean surface currents are poorly known near the Equator and globally for spatial scales under 200 km and timescales under 30 d. Wide-swath radar Doppler measurements are an alternative technique. Such direct surface current measurements are, however, affected by platform motions and waves. These contributions are analyzed in data collected during the DRIFT4SKIM airborne and in situ experiment, demonstrating the possibility of measuring currents from space globally.

Carbon flux between air and sea is known to fluctuate in response to inherent climate variations. In this study, observed ocean hydrographic data were assimilated into Earth system models, and the carbon flux in the equatorial Pacific was evaluated. Our results suggest that, when observed ocean hydrographic data are assimilated into models for carbon cycle predictions on interannual to decadal timescales, the reproducibility of the internal climate variations in the model itself is important.

During the mid-1970s 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 reoccurrence time of this polynya seems arbitrary. In this study, we address the reoccurrence 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.

Our investigations give detailed insight on the seasonally changing current system at intermediate depth in the Arabian Sea that is influenced by the monsoon. The changing currents influence the oxygen transport in the interior ocean and thus allow us to draw conclusions on the maintenance and seasonal variability of the upper part of the oxygen minimum zone in the Arabian Sea.

The upper mixed layer, shallower than the depth of the euphotic zone, is one of the preconditions for enhanced primary production in the ocean. In the Baltic Sea, the general understanding is that the upper mixed layer is much deeper in winter. In this study, we demonstrate that wintertime shallow stratification and an elevated phytoplankton biomass proxy, chlorophyll, are common in the Gulf of Finland. Stratification is invoked by the westward flow of riverine water forced by an easterly wind.

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 WRF atmospheric model, the WAVEWATCH III® wave model, and the GETM regional ocean model as well as 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.

The performance of Earth system models should be evaluated before their application for the study of climate change. We assessed the relationship between the NAO and winter sea surface temperature (SST) of the North Atlantic (NA) simulated by 13 CMIP5 models. There are some unrealistic links between the SST and NAO-driven turbulent heat fluxes in some models, which leads to the deviation of the simulated locations of response centers of the SST to the NAO in the subpolar NA.

The rate of change in the marine environment along the south coast of South Africa (32–37° S, 20–30° E) is studied using reanalysis observations for 1900–2015 and coupled ensemble model projections for 1980–2100. Although sea surface temperatures offshore are warming rapidly, a trend toward easterly winds and stronger shelf-edge currents have intensified nearshore upwelling (−0.03 °C yr⁻¹) and contribute to a drier climate.

Mesoscale datasets are used to study coastal gradients in the marine climate and oceanography of False Bay, south of Cape Town. Building on past work, satellite and ocean–atmosphere reanalyses are used to gain new insights into the mean structure, circulation and meteorological features. HYCOM v3 hindcasts represent a coastward reduction of mixing that enhances stratification and productivity in False Bay during summer.

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 C_ant and dissolved inorganic carbon increased at about the same rate over the 40-year 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 water formation and circulation in the Southern Ocean.