Recent analysis of data from a high resolution global ocean model showed, in conflict with conventional theory, that the North Equatorial Counter Current was responsible for the unusually warm water which triggered the strong El Niños of 1982–83 and 1997–98. In this paper some of the key physics deduced from the model results is tested against satellite data from the 1997–98 event. The results show that the model closely followed reality during the period further supporting the new mechanisms.

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

We present a first direct comparison of fraternal versus identical twin approaches for an ocean data assimilation system. We show that the identical twin approach overestimates the value of assimilating satellite observations and undervalues the benefit of assimilating temperature and salinity profiles. Misleading assessments such as undervaluing the impact of some observational assets are problematic and can lead to misguided decisions on balancing investments among different observing assets.

The ocean is one of the important components of the ocean-atmosphere coupling system. The Sea Surface Temperature (SST) is the basis for the interaction between the ocean and the atmosphere, and it characterizes the combined results of ocean heat, dynamic processes. The variability of the sea surface temperature (SST) in the Northwest Pacific has been studied on seasonal, annual and interannual scales based on the monthly datasets of ERSST and OISST.

We describe 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 analysed. The poleward flow is strengthened during the observed time period, likely by a downwelling coastal trapped wave, the stronger current cause an increase in nitrate and reduces the deficit of fixed nitrogen.

This research considers the physical environmental factors that underpin changes in ocean productivity over the shelf of South Africa, where coastal upwelling occurs next to a warm current. Statistical analysis of model assimilated data show that salinity and wind play prominent roles in changes of chlorophyll content, with possible consequences for the coastal fishery.

Recent studies suggest that the sea surface microlayer is ubiquitously enriched in surfactants, even at high wind speeds, which exert a control on air-sea gas exchange. These conclusions are partly based on voltammetry measurements of surfactant activity (SA). Here, we show that the response of SA-voltammetry varies widely for different surfactants, becomes saturated above total surfactant concentrations of 1–2 mg L^-1, and shows a poor correlation in natural waters with surface film pressure.

The effects of floating solar platforms on the marine ecosystem must be known for responsible field implementations. We modelled effects of floating platforms on water flow and algae growth in a coastal sea. Algae growth reduced, depending on the local currents and on the density of coverage with platforms. The model represented platforms distributed evenly over areas of hundreds of square kilometres. For more detail and smaller-scale cases, three-dimensional models are needed.

Data from the ARKTIKA-2018 expedition and new satellite data help better understand the upper layer of Laptev and East-Siberian seas (LS and ESS). With an improved method of the surface salinity estimates from space and satellite wind, we follow distribution and mixing of the Lena river and other waters in summer 2018. Prevailing winds push it far north of the LS and under the ice of the ESS and generate vast downwelling in LS in August. Proposed water mass classification indicates water origin.

The Caspian Sea is the largest enclosed basin on the Earth and a unique object for analysis of tidal dynamics. Using the Princeton Ocean Model (POM), we examine the spatial and temporal features of tidal dynamics in the Caspian Sea in detail. The maximum tidal range has been observed in the Turkmen Bay, up to 21 cm. The highest velocity of the total tidal currents is observed in the straits to the north and south of Ogurja Ada, up to 22 cm/s and 19 cm/s, respectively.

The idea of this study is to quantify the uncertainty in hindcasts of severe storm events by applying a state-of-the-art ensemble generation technique. Other ensemble generation techniques are tested. The atmospheric WRF model is driven by the ERA5 reanalysis. A setup of the Wavewatch III^® wave model for the Baltic Sea is used with the wind fields produced with the WRF ensemble. The effect of different spatiotemporal resolutions of the wind fields on the significant wave height is investigated.

Due to climate change an accelerated mean sea level rise is expected. Numerical hydrodynamic models help to understand how mean sea level rise changes tidal dynamics. One limiting factor is the resolution of the model grid. In this study we show that especially in flat coastal areas such as the Wadden Sea in the German Bight the representation of the bathymetry plays a crucial role for the estimation of changed tidal dynamics in response to mean sea level rise.

The northern Baltic Sea shows, in contrast to the central parts, well oxigenated bottom water. Details of the ventilation are not well investigated. In this study, we analyzed data obtained at a research vessel in March 2017 in the northern Baltic Sea. We followed two hypothesis (i) ventilation due to lateral inflows or (ii) vertical convection due to brine release from sea ice. Our data reveal that lateral inflows most likely ventilate the Bottom water in the northern Baltic Sea.

Data from three campaigns was combined to look at the enrichment of gel particles, who act as a large source of organic matter transport, in the sea surface microlayer. Additionally depth profiles showed that the vertical distribution in the upper 2 meters of the ocean can be both homogeneously and heterogeneously mixed. This highlights the importance of depth on measurements when studying enrichment and the complexity of the near surface environment.

The Red Sea holds one of the most diverse marine ecosystems in the world, although fragile and vulnerable to ocean warming. To better understand the long-term variability and trends of the temperature in the whole water column, we produce a 3D gridded temperature product (TEMPERSEA) for the period 1958–2017, based on a large number of in situ observations, covering the Red Sea and the Gulf of Aden.

Bottom pressure estimates from three GRACE gravity series and two global ocean models are compared to Jason altimetry sea level anomaly estimates, to determine the accuracy of the GRACE and model data at sub-monthly time scales. The GRACE series can explain 25–75 % of the sub-monthly altimetric variability in most ocean regions with high signal strength. The GRACE series explain more of the sub-monthly variability than their de-aliasing model products can, to periods as short as 10 days.

We carried out a literature review and an opinion poll of the JERICO-NEXT community to identify the main environmental threats in European coastal areas, and gaps in monitoring. The need for improved monitoring was highlighted, e.g. through improved design and monitoring effort and better links with new technologies. The findings underpin the JERICO-NEXT science strategy to integrate linkages between physical, chemical and biological parameters to address scientific and policy needs.

We investigated the spatial patterns and temporal changes in High-Salinity Shelf Water (HSSW) formation in Terra Nova Bay polynya using a large, collaboratively produced data set. We show that production of HSSW can occur at the surface of the eastern Terra Nova Bay via wind-driven mixing and polynya activity, and how the nature of circulation in Terra Nova Bay influences HSSW production. The last part of this article compares the results with historical observations in Terra Nova Bay.

The study evaluates how much bioavailable nitrogen is contributed to the nitrogen budget of the western Baltic Sea by deposition of shipping-emitted nitrogen oxides. Bioavailable nitrogen compounds are nutrients for phytoplankton (algae). Excessive input of nutrients into water bodies may lead to eutrophication: more algal blooms and, subsequently, oxygen limitation at the sea floor. Hence, reducing shipping emissions might reduce the anthropogenic pressure on the marine ecosystem.

Deep-sea connectivity research is scarce but needed for understanding marine population dynamics and dispersal of animal early-life stages. Here, we modeled near-bottom particle drifts along a continental margin crossed by submarine canyons. Bottom current impacting particle drifts is influenced by uneven topographic structures like submarine canyons. Thus, models with a good representation of the bottom geomorphological structures contribute to improving the deep-sea larval drift modeling.

In this work, 25-years of daily satellite data of absolute dynamic topography (ADT) show that before 2002 the Caribbean Surface Water (CW) was less intrusive inside the Gulf of Mexico. Our results suggests that from 2003 onward, larger volumes of oligotrophic waters from Caribbean Sea have invaded the western GoM and reduced mean surface Chl-a concentrations. A direct comparison between the 1998–2002 and 2009–2014 periods indicates that, Chl-a concentration has decreased significantly.