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Ocean Science An interactive open-access journal of the European Geosciences Union

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The Alboran Sea is a dynamically active region. The interaction between Mediterranean and Atlantic water originates a set of sub-mesoscale structures and a complex sequence of processes that entail mixing close to the thermocline. Here we present a high-resolution map of the diapycnal diffusivity around the thermocline depth obtained using acoustic data recorded with a high-resolution multichannel seismic system. The map revels a patchy thermocline, with areas of strong diapycnal mixing.

Jhon F. Mojica, Valentí Sallarès, and Berta Biescas

To assist in establishing the most likely location of the crash site of MH370, a Boeing 777 aircraft that went missing on March 7, 2014, a drift study was conducted by means of numerical modelling. Three elements were considered: (a) the efficacy of the aerial search; (b) water temperatures along the path of the flaperon; (c) beached debris distribution. The results obtained indicate the crash site is likely located between 25.5°S and 30.5°S along the so-called seventh arc in the Indian Ocean.

Oleksandr Nesterov

We estimated spatial and temporal decorrelation scales of temperature and salinity in the Amerasian Basin in the Arctic Ocean. The estimated scales can be applied to representation error assessment in the ocean data assimilation system for the Arctic Ocean.

Hiroshi Sumata, Frank Kauker, Michael Karcher, Benjamin Rabe, Mary-Louise Timmermans, Axel Behrendt, Rüdiger Gerdes, Ursula Schauer, Koji Shimada, Kyoung-Ho Cho, and Takashi Kikuchi

A new density–salinity relation of standard seawater was developed based on highly accurate density measurements. The comparison of densities calculated using the new relation with those using the reference equation of state TEOS-10 showed significant deviations that are likely caused by accuracy overestimations of some density data underlying TEOS-10 and EOS-80. The new relation enables the determination of seawater density from salinity and vice versa with unprecedented accuracy.

Hannes Schmidt, Steffen Seitz, Egon Hassel, and Henning Wolf

A coupled model has been developed to study the interaction between the ocean and the Antarctic ice sheet. Simulations for present-day climate yield realistic ice-shelf melt rates and a grounding line position close to the observed state. In a warm-water-inflow scenario, the model suggests a substantial thinning of the ice shelf and a local retreat of the grounding line. The coupled model yields a stronger increase in ice-shelf basal melt rates than a fixed-geometry control experiment.

Ralph Timmermann and Sebastian Goeller

Some places experience double high tides, where the tide starts to ebb for a short while, only to briefly flood again before finally receding. The result is a very long high tide with weak currents, and is important for navigational purposes. The existing theory for when and where double high tides occur does not always capture them, and it can only be applied to double highs occurring on a twice-daily tide. Here, the criterion has been generalized to capture all double high or low tides.

Hannah A. M. Byrne, J. A. Mattias Green, and David G. Bowers

A new method of observing ocean heat content throughout the entire ocean depth is provided. The new method is compared with simulated ocean heat content changes from climate models. The comparisons are carried out in various depth layers of the ocean waters. It is found that there is excellent agreement between the models and the observations. Furthermore, we propose that changes to ocean heat content be used as a fundamental metric to evaluate climate models.

L. Cheng, K. E. Trenberth, M. D. Palmer, J. Zhu, and J. P. Abraham

Lee waves play a significant role in ocean mixing but are difficult to study with traditional casts, moorings, and tows due to their stationary nature and limited spatial extent. We develop a new method to estimate turbulent diffusivity from seismic data and find elevated levels of turbulence associated with lee waves in the mid-water and around the seafloor that are 5 times greater than surrounding waters and 50 times greater than open-ocean diffusivities.

W. F. J. Fortin, W. S. Holbrook, and R. W. Schmitt

Regional sea surface height (SSH) changes due to an abrupt weakening of the Atlantic meridional overturning circulation (AMOC) are simulated with a high- and low-resolution model. A rapid decrease of the AMOC in the high-resolution version induces shorter return times of several specific regional and coastal extremes in North Atlantic SSH than in the low-resolution version. This effect is caused by a change in main eddy pathways associated with a change in separation latitude of the Gulf Stream.

S.-E. Brunnabend, H. A. Dijkstra, M. A. Kliphuis, B. van Werkhoven, H. E. Bal, F. Seinstra, J. Maassen, and M. van Meersbergen

We use ocean bottom-pressure measurements from 17 tropical sites to determine the annual cycle of ocean mass. We show that such a calculation is robust, and use three methods to estimate errors in the mass determination. Our final best estimate, using data from the best sites and two ocean models, is that the annual cycle has an amplitude of 0.85 mbar (equivalent to 8.4 mm of sea level, or 3100 Gt of water), with a 95% chance of lying within the range 0.61–1.17 mbar.

Joanne Williams, C. W. Hughes, M. E. Tamisiea, and S. D. P. Williams

The Atlantic meridional overturning circulation comprises warm upper waters flowing northward, becoming colder and denser until they form deep water in the Labrador and Nordic Seas that then returns southward through the North and South Atlantic. The ocean heat transport associated with this circulation is 1.3 PW, accounting for 25% of the maximum combined atmosphere–ocean heat transport necessary to balance the Earth's radiation budget.

H. L. Bryden, B. A. King, G. D. McCarthy, and E. L. McDonagh

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