Recent  

The Equatorial Undercurrent (EUC) plays a central role on the circulation and hydrography on tropical Pacific, with notable influence at the eastern boundary and coastal upwelling off Peru. By tracking virtual particles, we find that the EUC contribution to Peruvian upwelling is highly variable from year to year and related to El Niño Southern Oscillation (ENSO). The EUC contribution is more substantial during the cold and warm phases of ENSO, when a major shift in marine population occurred.

Based on the near-synchronous oceanographic and ocean chemical data from 2006 to 2007, the present manuscript shows the magnitude, distribution characteristics, and formation mechanism of Absolute Salinity in China offshore. These results are valuable supplements for the new worldwide standard for oceanography, the international Thermodynamic Equation of Seawater-2010 in which the Absolute Salinity algorithm is not very clear to date in the offshore and semi-closed sea due to the lack of data.

We tested the stability of a well-characterized seawater pH buffer, tris, during long-term storage in gas impermeable bags. Tris is used to validate pH measurements; it is critical that we understand how its chemistry changes over time. Correspondingly, we prepared multiple batches of tris buffer in artificial seawater, stored the buffer in multiple types of gas impermeable bags, and analyzed its pH over the course of 300 days, discovering an average drift of −0.006 yr⁻¹.

In the North Atlantic, ocean currents carry warm surface waters northward and return cooler deep waters southward. This type of ocean circulation, known as overturning, is important for the Earth's climate. This overturning has been measured using a mooring array at 26° N in the North Atlantic since 2004. Here we use this mooring data and global satellite data to produce a new method for monitoring the overturning over longer timescales, which could potentially be applied to different latitudes.

In the oceanic surface layer, the temperature, salinity, and density are mixed well vertically. And the depth of this layer is called mixed layer depth. The mixed layer depth is important because it is related to climate change. We obtained the mixed layer depth by measuring the salinity and the temperature in the Chukchi Sea and the Bering Sea in the summer of 2019, and found that the factors that might influence the mixed layer depth include ocean current, wind, heat and water flux.

The ocean absorbs a large proportion of the excess heat and anthropogenic carbon in the climate system. This uptake is modulated by air-sea fluxes and by the processes that transport water from the surface into the ocean's interior. We performed numerical simulations with interannually-varying passive tracers and identified the key role of surface atmospheric forcing in setting the longer-term variability in the distribution of the tracers after they are transported below the ocean's surface.

The Indian ocean receives a large proportion of plastics but very few studies have addressed the sources, transport pathways and sinks. There is a scarcity of observational data for the Indian ocean. Majority of the plastic sources are derived from rivers although the amount derived from fishing activity (ghost nets, discarded ropes) are unknown. The unique topographic features of the Indian ocean that create the monsoons and reversing currents have a large influence in the transport and sinks.

Compared to other freshwater sources, runoff from Iceland is small and usually flows into the Nordic Seas. Under certain wind conditions, it can, however, flow into the Iceland Basin and this occurred after 2014, when this region had already freshened from other causes. This explains why the surface freshening in this area became so extreme. The local and shallow character of this runoff allows it to have a disproportionate effect on vertical mixing, winter convection, and biological production.

Research on strong El Niños has shown that they may be triggered by a stronger than normal North Equatorial Counter Current (NECC). A computer model used to study the increased NECC, prior to the 1982–1983 El Niño, showed that it was due to strong westerly winds close to the Equator. Previously such winds were thought to affect El Niños by reversing ocean currents close to the Equator. However this study shows that it is their effect on the NECC which is critical.

This study quantifies the influence of ocean eddies and other mesoscale phenomena (spanning 50–1000 km) on heat movement. One finding is that mesoscale processes spread heat outwards from the subtropical latitudes towards both the equator and the poles. The effect of major ocean currents on heat movement in the ocean depends on the currents' mesoscale structure. Mesoscale processes also impact year-to-year changes in heat movement, especially at middle latitudes and in the tropical Pacific.

Accurate and significant wave height prediction with a couple of hours of warning time should offer major safety improvements for coastal and ocean engineering applications. However, significant wave height phenomenon is nonlinear and nonstationary, which makes any prediction simulation a non straightforward task. The aim of the research presented in this paper is to improve predicted significant wave height via a hybrid algorithm.

This paper presents an analysis of wind and warming sensitivity experiments in order to provide insight into the Atlantic inter-hemispheric circulation by understanding the behavior of the depth scale(s) of the AMOC. We put into question the common view that the AMOC is a nonlocal phenomenon only. The analysis of the wind experiments and the warming experiment suggests a hemisphere-dependent scaling of the strength of AMOC and temporal adjustment to global warming.

This paper presents an efficient method for high-resolution ocean modelling based on a combination of the deterministic and stochastic approaches. The method utilises mathematical tools similar to those developed for data assimilation in ocean modelling. The main difference is that instead of assimilating a relatively small number of observations, the SDD method assimilates all the data produced by a parent model. The method is applied to create an operational Stochastic Model of the Red Sea.

Mesoscale eddies are an important part of the turbulent motion in the oceans, constituting coherent structures that can live for years storing physical properties anomalies. Analysis of anticyclones (clockwise rotating eddies) tracks in the eastern Levantine basin revealed statistical patterns over 19 years of data, in particular the presence of an anticyclone attractor above the Eratosthenes seamount, with a strong heat content signature.

Little is known about the impact of chlorophyll on SST in the Bay of Bengal (BoB). Solar irradiance measured by an ocean glider and three Argo floats are used to determine the effect of chlorophyll on BoB SST during the 2016 summer monsoon. The Southwest Monsoon Current has high chlorophyll concentrations (~ 0.5 mg m⁻³) and shallow solar penetration depths (~ 14 m). Ocean mixed layer model simulations show that SST increases by 0.35 °C month⁻¹ with the potential to influence monsoon rainfall.

Experiments in the rotating tanks can simulate the earth system and help to represent the real ocean where the rotation plays an important role. We want to show the minor importance of the wind in driving the flow in the Ionian Sea. This we show by observing changes of water current in the rotating tank affected only by pumping of the dense water into the system. The flow variations are alike to what happens in the real sea confirming the scarce importance of the wind for the flow in the Ionian.

This special issue marks the 100th anniversary of the Liverpool Tidal Institute. This preface summarises how the LTI came about and the roles of its first two Directors. It also gives an overview of research on tides at the LTI. Summaries are given of the 26 papers in the special issue. The topics of many of them could be thought of as providing a continuation of the research first undertaken at the LTI. They provide a snapshot of work on tides now being made by groups around the world.

Satellite altimetry have revolutionized the ocean observation by monitoring the sea level with a very good spatio-temporal coverage. However, only the sea level anomalies are retrieved; to monitor the whole oceanic signal a temporal mean (called MDT=Mean Dynamic Topography) must be added to these anomalies. In this study we present the newly updated CNES-CLS18 MDT. An evaluation of this new solution shows significant improvements both in strong currents and coastal areas.