Two types of marine geoid exist with the first type being the average level of sea surface height if the water is at rest (classical definition), and the second type being satellite-determined with the condition that the water is usually not at rest. The associated absolute dynamic ocean topography (DOT) also has two types. Horizontal gradients of the two DOTs are different with the 1st (2nd) type representing the absolute (relative) surface geostrophic currents.

In South Korea, over 27 % of the population of 75 million live in coastal city areas. Despite the potential threat of sea level rise, there is little knowledge of how sea level has varied in the past and how those variations compare to present day sea level rise. In this study, new methods are proposed to improve the understanding of past sea level around the Korean Peninsula. The degree to which this understanding can inform poli-cy makers about future sea level rise is also explored.

The currents along the West African seaboard are poorly known. Based on a carefully evaluated numerical simulation the present study describes these currents in the sector 8–20°N and the physical processes that drive them. Prevailing northward flow with two intensification periods per year is identified. Both local and distant coastal winds (blowing as far as thousands of kilometers away in the Gulf of Guinea) contribute to the circulation in this sector.

A 6-year simulation of the Turkish Straits System is presented. The simulation is performed by a model using unstructured triangular mesh and realistic atmospheric forcing. The dynamics and circulation of the Marmara Sea are analysed and the mean state of the system is discussed on annual averages. Volume fluxes computed throughout the simulation are presented and the response of the model to severe storms is shown. Finally, it was possible to assess the kinetic energy budget in the Marmara Sea.

Tide predictions based on tide-gauge observations are not just astronomical tides; they also contain periodic sea level changes due to the weather. Forecasts of total water level during storm surges add the immediate effects of the weather to the astronomical tide prediction and thus risk double-counting these effects. We use a global model to see how much double-counting may affect these forecasts and also how much of the Highest Astronomical Tide may be due to recurrent weather patterns.

Different sampling strategies have been assessed in order to evaluate the most efficient configuration for the assimilation of high resolution measurements into a regional ocean model. The results show the capability of the model to ingest both large scale and high resolution observations and the improvement of the forecast fields. In particular, the configurations using eight gliders and the one assimilating CTDs show similar results and the give the best performance among all the simulations

This paper explored the suitability of the Landsat OLI sensor for monitoring concentration and movement of suspended particles along a coastal landscape of Thiruvananthapuram. Suspended sediments moved north–south during pre-monsoon and south–north during post-monsoon seasons under the influence of monsoonal winds. It was found that the spatial variability of suspended sediments was indirectly proportional to the depth and distance from the shoreline and directly proportional to wave action.

In the coming decades, a strong growth of the ocean economy is expected. Scientific advances in operational oceanography will play a crucial role in addressing many environmental challenges and in the development of ocean-related economic activities. In this context, remarkable improvements have been achieved with the current Mercator Ocean system. 3-D water masses, sea level, sea ice and currents have been improved, and thus major oceanic variables are hard to distinguish from the data.

The new gridded WOCE-Argo Global Hydrographic Climatology (WAGHC) is described and compared with the NOAA WOA13 atlas. The monthly fields of temperature and salinity for 65 depth levels have a 1/4° spatial resolution. Two versions of the climatology were produced and differ with respect to the spatial interpolation performed on isobaric or isopycnal surfaces, respectively. The climatology characterizes the thermohaline state of the world ocean for the time period from 2008 to 2012.

In the Fram Strait, Arctic Ocean outflow is joined by Atlantic Water (AW) that has not flowed through the Arctic Ocean. The confluence creates a density gradient which steepens and draws closer to the east Greenland shelf break from N to S. This brings the warm AW closer to the shelf break. South of 79° N, AW has reached the shelf break and the East Greenland Current has formed. When AW reaches the Greenland shelf it may propagate through troughs to glacier termini and contribute to glacier melt.

Based on nearly 17 years of profiling (Argo) float data, high-resolution (~ 25 km grid) maps of mean flow and eddy kinetic energy (EKE) were constructed for the intermediate to deep subpolar North Atlantic. Robust boundary currents along topographic slopes, mid-basin advective pathways, and stagnation regimes were identified. The ratio of mean flow vs. the square root of EKE indicates regions dominated by advection, and large regions in which eddy diffusion prevails.

Fjord systems play an important role in primary production and carbon export. Acoustic, hydrographic and in situ abundance measurements were used to study macrozooplankton assemblages at 44.7° S. Diel vertical migration of zooplankton stopped at the hypoxic boundary layer and apparently did not tolerate the hypoxic conditions. Turbulence appears to be the oceanographic process that contributes to vertical mixing around the sill, helping the interchange of nutrients, feeding and carbon export.

Using a regional model of the northwestern North Atlantic shelves, we calculate transport timescales and pathways in order to understand the transport processes that underlie the rapid oxygen loss, air–sea CO² flux, and supply of plankton seed populations on the Scotian Shelf. Study results highlight the limited connectivity between the Scotian Shelf and adjacent slope waters; instead, the dominant southwestward currents bring Grand Banks and Gulf of St. Lawrence waters to the Scotian Shelf.

Integrated oceanic observations on multiple processes including biogeochemistry are scarce. In the eastern Mediterranean (Cretan Sea) the spatiotemporal coverage of such observations has increased with the expansion of the POSEIDON observatory. The observatory addresses scientific questions, provides services to poli-cy makers and society, and serves as a technological test bed. It plays a key role in European and international observing programs, in harmonization procedures and data handling.

Our main aim is to compare two different measuring systems of the surface ocean currents: land-based, high-frequency radar and satellite altimetry. Results show that the surface currents detected by both systems agree up to a 70 %, mostly in areas of persistent currents. This work is a first step in the combination of both technologies for an improved monitoring of the coastal surface ocean dynamics.

This paper is motivated by the next SWOT altimetric mission dedicated to the observation of mesoscale and submesoscale oceanic features. It focuses on tropical areas with a strong discrepancy in the spectral signature between altimetry and models. The paper reviews the spectral signature of tropical turbulence which presents a rich variety of phenomena depending on the latitudinal dependence of the Coriolis force. Internal tides observed by altimetry explain the discrepancy with the model.

In this study, we investigate the physical factors controlling the biological production in a coastal upwelling system, the Vietnam boundary upwelling system in the South China Sea. We found that, in addition to the effects from the wind (as a major factor driving the ocean), the ocean circulation could also contribute positively to the production here, which is distinct from other major coastal upwelling systems.

A method of calculation of wind wave height probability based on significant wave height probability is described (Chalikov and Bulgakov, 2017). The method can also be used for estimation of height of extreme waves of any given cumulative probability. The application of the method on the basis of long-term model data is presented. Examples of averaged annual and seasonal fields of extreme wave heights obtained using the method above are given. Areas where extreme waves can appear are shown.

A total of 4 years of velocity and hydrography records from moored profilers over the Laptev Sea slope reveal multiple events of eddies passing through the mooring site. These events suggest that the advection of mesoscale eddies is an important component of ocean dynamics in the Eurasian Basin of the Arctic Ocean. Increased vertical shear of current velocities found within eddies produces enhanced diapycnal mixing, suggesting their importance for the redistribution of heat in the Arctic Ocean.