Data assimilation is the most comprehensive strategy to estimate the biogeochemical state of the ocean. Here, surface Chl-a data are daily assimilated into a 24 member NEMO-PISCES ensemble configuration to implement a complete 4D assimilation system. Results show the assimilation increases the skills of the ensemble, though a regional diagnosis suggests that the description of model and observations uncertainties needs to be refined according to the biogeochemical characteristics of each region.

AMOC controls climate and is driven both by wind and buoyancy-driven formation of North Atlantic Deep Water. Density changes are expected to connect to tropical regions. Since we have observations at 26N, we develop methods to identify density profiles at 26N at the boundaries which relate to AMOC. Polar density anomalies propagate equatorward along the western boundary, then eastward along the equator and poleward up the eastern boundary. We found 2 years lag between boundaries at 3000 m.

High Frequency Radar technology measures coastal ocean surface currents. The use of this technology is increasing as it provides near-real time information that can be used in oil spill or search and rescue emergencies to forecast the trajectories of the floating objects. In this work, a Short-Term Prediction methodology is presented and it provides surface currents’ forecasts of up to 48 hours. The primary advantage of it, is that it is easily implemented in real time.

Our investigations give a detailed insight on the changing current system at intermediate depth in the Arabian Sea and allows to draw conclusion on the maintenance and seasonal variability of the oxygen minimum zone, that is influenced by the monsoon.

The dynamical balance of the Antarctic circumpolar current and their implications on the functioning of the world ocean are not fully understood and poorly represented in global circulation models. In this study, the sensitivities of an idealized Southern Ocean (SO) storm track are explored with a set of eddy-rich numerical simulations. We show that the classical partition between barotropic and baroclinic modes is sensitive to current-topography interactions in the mesoscale range 10-100 km.

This study provides for the first time estimates of sea level anomalies very close to the coastline, based on high-resolution retracked altimetry data, as well as corresponding sea level trends over a 14-year time span. This new information so far not provided by standard altimetry data.

Very little is currently known about the activities and emissions of private leisure boats. To change this, a new model was created (BEAM). The model was used for the Baltic Sea to estimate leisure boat emissions, also considering antifouling paint leach. When compared against commercial shipping, the modelled leasure boat emissions were seen to be surprisingly large for some pollutant species, and these emissions heavily concentrated on coastal inhabitated areas during summer and early autumn.

Witness King Tides (WKT) is a citizen-science project collecting photos of the shoreline at the time of highest predicted tide each year, with the aim of indicating the flooding that may occur routinely with sea-level rise. However, effects such as storm surges may affect the results, leading to significantly lower tides than expected. Tidal observations from the GESLA-2 global database are analysed to indicate regions of the world where WKT should perform well and others where it would not.

The paper discuses averaged daily water level variations in Gulf of Riga for each season. Does the daily pattern result from gravitational tides or sea/land breeze for given month? Results show that their interference is vital from March to October. Water level has typically a distinct maximum in late afternoon for April-May when the forcing by gravity of the Sun is nearly in phase with its radiation effect. The opposite occurs for the September when both effects cancel each other in average.

Marine electromagnetic (EM) signals largely depend on three factors: 1) the direction and speed of ocean flow, 2) the strength of Earth’s main magnetic field, and 3) seawater’s electrical conductivity (which depends on the local temperature and salinity). Because of this, there is interest in using marine EM signals to monitor and study ocean circulation. Our study investigates using voltage data from retired seafloor telecommunication cables in the Pacific Ocean to monitor large-scale flows.

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 is increasing since 2009, this increase is not statistically significant.

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

The role of oceans in the global mercury cycle is poorly understood. Investigation of sediments revealed that biological productivity and scavenging of water phase mercury by sinking algae or algae derived organic matter controlled preindustrial mercury accumulation in Adélie Basin. Our study suggests that the periodic-like variations in Hg concentrations and accumulation rates are likely associated with the cycle of polynya opening and closing and its related changes in biological productivity.

The input of mechanical power to the ocean due to the surface wind-stress is considered using data from satellites observations. Its dependence on the coarse-graining scale of the atmospheric and oceanic velocity in space and time is determined. The power input is found to increase monotonically with shorter coarse-graining in time. Results show that including the dynamics at scales below a few degrees reduces considerably the power input by air-sea interaction.

On ice affected coasts obtaining yearlong sea level records for traditional tidal predictions is difficult. We evaluate the Complete Tidal Species Modulation with Tidal Constant Corrections (CTSM+TCC) method for predicting tides at the 'mixed, mainly diurnal' Jang Bogo Antarctic Research Station in the Ross Sea, Antarctica, using short in situ records plus longer records from the nearby 'diurnal' Cape Roberts. The method proved successful using data from periods with above average tidal ranges.

We investigated the impact of indicator dye impurities on spectrophotometric seawater measurements, especially how they may influence the drift behavior and the measurement quality of an autonomous analyzer using this indicator. These measurements are important for ocean carbon observations. This work revealed that impurities up to a quantity of 2 % do not influence the measurement drift and quality. Higher impurity levels lead to a changing drift behavior and quality deteriorations.

This project is part of the graduate school Baltic Transcoast. This graduate school aimed to investigate the interaction between a coastal fen and the Baltic sea. In this work, the mixing and transport of the submarine groundwater discharge (SGD) was investigated in a defined laboratory experiment. For this, a new wave channel ground model was constructed and produced to facilitate the variation of different parameters for the investigations.