We compared observations from the operational Time Series Station Spiekeroog, related to water transparency, conducted correlation tests among these measured parameters, and explored the utility of both acoustic and optical tools in monitoring water transparency. Our findings suggest that both optical and acoustic measurements can be reasonable proxies of water transparency with the potential to mitigate gaps and increase data quality in long-time observations of marine environments.

We use satellite and in situ data to elucidate global-mean sea level (GMSL) changes related to El Niño-Southern Oscillation (ENSO) over 2005–2015. Steric and mass effects make comparable contributions to the GMSL budget during ENSO, in contrast to previous interpretations based largely on hydrological models, which emphasize mass contributions. Results exemplify the usefulness of the Global Ocean Observing System for understanding the Earth's radiation imbalance and hydrological cycle.

Satellite altimetry measures changes in sea level, while satellite gravimetry measures mass changes, and one can infer steric sea level from Argo temperature and salinity profiles. For the first time, it is shown that in most cases the mass and steric components match the total sea level measured by altimetry on a sub-basin scale in terms of trend, annual amplitude and interannual variability. We also find that the choice of gravity field filter is essential to close the budget.

The Faroe Bank Channel is one of the main passages for the flow of cold dense water from the Arctic into the depths of the world ocean where it feeds the deep branch of the AMOC. Based on in situ measurements, we show that the volume transport of this flow has been stable from 1995 to 2015. The water has warmed, but salinity increase has maintained its high density. Thus, this branch of the AMOC did not weaken during the last 2 decades, but increased its heat transport into the deep ocean.

Ripples are small regular sand waves found on beaches or the floor of rivers and coastal seas. Their shapes and dimensions are controlled by properties of the sand and the strength of waves and currents. The form of ripples can be predicted by mathematical formulas which were often developed from laboratory experiments. In this work, we present methods for measurement of ripple heights and lengths from the North Sea and compare the results to calculated dimensions.

Here we introduce a new molecular-based observation strategy for high-resolution assessment of marine microbes (e.g., microalgae) in space and time. The observation strategy combines automated sampling on board ships or observation platforms with a variety of different molecular genetic methods for refined observation of marine microbes at adaquate scales, in order to better understand the impact of climate change on this group of organisms, which are at the base of marine food webs.

The Genealogical Evolution Model (GEM) is an efficient logical model used to track dynamic evolution of mesoscale eddies in the ocean. It can distinguish different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern with a two-dimensional vector. All of the computational steps are linear and do not include iteration. It is very fast and is potentially useful for studying dynamic processes in other related fields, e.g., the dynamics of cyclones in meteorology.

In this study, the MERIS (ocean colour sensor from European Space Agency) algorithm for the quantification of chlorophyll a in coastal waters – API2 – is investigated in an area located in the Atlantic off the southwestern Iberian Peninsula. The study demonstrates the importance of regional algorithms for the study area that could complement upcoming standard results of the present Sentinel-3/OLCI space mission.