Abstracted/indexed

On top of forced changes such as human-caused global warming, unforced climate variability exists. Most multidecadal variability (MV) involves in the oceans, but current climate models use non-tubulent, coarse resolution oceans. We investigate the effect of resolving some important turbulent ocean features on MV. We find that ocean heat content and ocean-atmosphere flux MV is much more pronounced in the higher resolution model, but this barely affects global mean surface temperature MV.

The extremely powerful jets of currents induced by vessels propellers in big passenger ports often induce unpredicted areas of erosion and deposition strongly impacting the ports operability. The capacity to fully understand and even predict these complex dynamics would be a tremendous help for ports operators in order to optimize the operational managing of the basins. In the present work we show how this is feasible by means of high-resolution modeling of hydrodynamics and sediment transport.

Environmental issues arising due to coastal modification and future sea level scenarios is the major environmental hazard facing the Maldives today. Here, we carry out high resolution tidal modelling of a Maldivian atoll for the first time and show that coastal modification in the island scale is capable of driving large scale change in the wider atoll basin in a short time, comparable to that of long term sea level rise scenarios and on par with observations.

In this study, we use a numerical hindcast at high resolution (1/12°) to examine the occurrence and properties of Rossby waves in the North Atlantic between 1970–2015. We show evidence of Rossby waves travelling at 39° N at a speed of 4.17 cm s⁻¹. These results are consistent with baroclinic Rossby waves generated by the North Atlantic Oscillation in the central North Atlantic and travelling westward before interacting with the Gulf Stream transport with a time lag of about 2 years.

An analysis of simulated German Bight surface currents reveals linear structures along which water bodies of different origin converge. Identification of these non-stationary structures supports the interpretation of monitoring data; observations gathered at stations that are neighbouring but separated by a line of convergence may substantially differ. The analysis could also be helpful for organizing field campaigns such that new observations do not just duplicate information already available.

Atlantic Waters that carry heat and anthropogenic Carbon into the Arctic Ocean play an important role in the Arctic sea-ice cover decline, but their pathways and travel times remain unclear. Here we used two radionuclides of anthropogenic origin (¹²⁹I and ²³⁶U) to track Atlantic-derived waters along their way through the Arctic Ocean, estimating their travel times and mixing properties. Results help to understand how future changes in Atlantic Water properties will spread through the Arctic.

We investigate how the freshwater budget of the Atlantic changes under climate change which has implications for the stability of the Atlantic Meridional Overturning Circulation. We compare the effect of ocean model resolution in a climate model and find many similarities between the simulations enhancing trust in the current generation of climate models. However, the overall ocean state is improved in the high resolution simulation and significant local freshwater budget differences exist.

The RAPID array has observed the Atlantic meridional overturning circulation (AMOC) since 2004, but the AMOC was directly calculated only five times from 1957–2004. Here we create a statistical regression model from RAPID data, relating AMOC changes to density changes within the different water masses at 26° N, and apply it to historical hydrographic data. The resulting 1981–2016 record shows that the AMOC from 2008–2012 was its weakest since the mid-1980s, but shows no overall decline.

This paper describes challenges around direct measurement of CO₂ in the ocean using ocean gliders. We discuss our method of using multiple sensor platforms as test beds for carrying out observing experiments and highlight the implications of our study on future glider missions. We also show high-resolution measurements and discuss challenges and lessons learned in the context of future ocean gas measurements.

We investigate the interactions between near-surface winds and oceanic surface currents on the north-east atlantic region using a simplified lower atmosphere model coupled with an ocean model. we show that the upper ocean kinetic energy is significantly reduced due to these interactions, but in a smaller amplitude than if the wind feedback is ignored. We also show that wind-current interactions affect the deeper ocean by modifying its vertical structure and consequently the pressure field.

A time-delayed positive (negative) correlation between the subsurface salinity (temperature) anomaly variability of the Bay of Bengal (BoB) and the Indian Ocean Dipole variability is found by analyzing multiple data sets. By applying a numerical model, it is demonstrated that coastal Kelvin waves, westward Rossby waves, and associated advection processes, play a crucial role in this correlation. Based on this, it is possible to predict the subsurface ocean state in the BoB.

Ocean mixing in the Arctic Ocean cools and freshens the Atlantic and Pacific-origin waters by mixing them with surrounding waters, which has major implications on global scale as the Arctic Ocean is a main sink for heat and salt. We investigate the drivers of ocean mixing north of Svalbard, in the Atlantic sector of the Arctic, based on observations collected during two research cruises in summer and fall 2018 as part of the Nansen Legacy project.

Changes in ocean temperature may affect vertical density stratification, which may hamper turbulent exchange and thus nutrient availability for phytoplankton growth. To quantify varying physical conditions, we sampled the upper 500 m along 17 ± 5° W between [30, 62]° N in summer. From south to north, temperature decreased with stratification while turbulence and nutrient fluxes remained constant, likely due to internal waves breaking and little affected by the physical process of global warming.

A Seaglider was deployed for 8 months in the Norwegian Sea mounting an oxygen and for the first time a CO₂ optode and a chlorophyll fluorescence sensor. The oxygen and CO₂ data were used to assess the spatial and temporal variability and calculate the net community production, N(O₂) and N(C_T). The dataset was used to calculate net community production from inventory changes, air-sea flux, and entrainment.