Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mixing it up: Study provides new insight into Southern Ocean behaviour

21.07.2014

A new study has found that turbulent mixing in the deep waters of the Southern Ocean, which has a profound effect on global ocean circulation and climate, varies with the strength of surface eddies – the ocean equivalent of storms in the atmosphere – and possibly also wind speeds.

It is the first study to link eddies at the surface to deep mixing on timescales of months to decades.


This image shows sensors from the DIMES project being used in the Drake Passage.

Credit: Katy Sheen

This new insight into how the Southern Ocean behaves will allow scientists to build computer models that can better predict how our climate is going to change in the future.

The findings are published in the latest issue of Nature Geoscience.

The Southern Ocean plays a pivotal role in the global overturning circulation, a system of surface and deep currents linking all oceans and one of the fundamental determinants of the planet's climate. The Southern Ocean around Antarctica is the only location where the ocean can circulate freely all the way around the globe without continental barriers.

Because the ocean is made up of many layers of water that are dependent on temperature and salinity, water moves easily along horizontal or 'isopycnal' layers, but mixes only slowly across the layers, known as 'diapycnal' mixing. This combination of diapycnal and isopycnal mixing drives the upwelling of deep waters up to the surface, forming an 'upper' and 'lower' overturning cell. When deep waters rise to the surface, they bring with them the nutrients that plankton need to grow. Conversely, as surface waters sink they take heat and dissolved CO2 from the atmosphere, strongly shaping regional and global climate change.

The researchers took measurements of small-scale temperature and velocity fluctuations, to measure the diapycnal movements in the Antarctic Circumpolar Current (ACC) across the Drake Passage region of the Southern Ocean.

The data revealed that, during the period of their measurements, turbulence in deep waters significantly correlated with surface eddy activity. The mechanism that causes eddies in the surface ocean leads to an intensification of currents in the top and bottom layers of the ocean. When such instability arises, strengthened bottom currents interact with rough bottom topography to generate internal waves that eventually devolve into turbulence. This process provides a source of energy for the mixing of abyssal waters, which, in turn, hastens the global overturning circulation.

The researchers established that deep water eddies are likely energised by strong westerly winds over the Southern Ocean that force the ACC and that abyssal mixing, on time scales of months to decades, reacts to this changing atmospheric climate.

Study co-author Katy Sheen, a Postdoctoral Research Fellow from Ocean and Earth Science at the University of Southampton, says: "These findings will help us to understand the processes that drive the ocean circulation and mixing so that we can better predict how our Earth system will respond to the increased levels of carbon dioxide that we have released into the atmosphere."

The researchers used data from the 'Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean' (DIMES) project, a UK/US field program aimed at measuring diapycnal and isopycnal mixing in the Southern Ocean. DIMES released a chemical dye tracer into the ACC about a mile below the sea surface. Over five years, the horizontal and vertical spread of the tracer was mapped out by measuring its concentration in hundreds of seawater samples, to identify how quickly the Southern Ocean moved water particles around. It also used a mooring cluster of sensors in the Drake Passage to provide detailed time series information on the processes responsible for the mixing of the tracer.

Glenn Harris | Eurek Alert!
Further information:
http://www.soton.ac.uk

Further reports about: DIMES sensors Earth Ocean activity atmosphere behaviour layers measurements mixing processes temperature topography

More articles from Earth Sciences:

nachricht Clouds and climate in the pre-industrial age
30.05.2016 | Goethe-Universität Frankfurt am Main

nachricht Researchers find higher than expected carbon emissions from inland waterways
25.05.2016 | Washington State University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Attosecond camera for nanostructures

Physicists of the Laboratory for Attosecond Physics at the Max Planck Institute of Quantum Optics and the Ludwig-Maximilians-Universität Munich in collaboration with scientists from the Friedrich-Alexander-Universität Erlangen-Nürnberg have observed a light-matter phenomenon in nano-optics, which lasts only attoseconds.

The interaction between light and matter is of key importance in nature, the most prominent example being photosynthesis. Light-matter interactions have also...

Im Focus: Worldwide Success of Tyrolean Wastewater Treatment Technology

A biological and energy-efficient process, developed and patented by the University of Innsbruck, converts nitrogen compounds in wastewater treatment facilities into harmless atmospheric nitrogen gas. This innovative technology is now being refined and marketed jointly with the United States’ DC Water and Sewer Authority (DC Water). The largest DEMON®-system in a wastewater treatment plant is currently being built in Washington, DC.

The DEMON®-system was developed and patented by the University of Innsbruck 11 years ago. Today this successful technology has been implemented in about 70...

Im Focus: Computational high-throughput screening finds hard magnets containing less rare earth elements

Permanent magnets are very important for technologies of the future like electromobility and renewable energy, and rare earth elements (REE) are necessary for their manufacture. The Fraunhofer Institute for Mechanics of Materials IWM in Freiburg, Germany, has now succeeded in identifying promising approaches and materials for new permanent magnets through use of an in-house simulation process based on high-throughput screening (HTS). The team was able to improve magnetic properties this way and at the same time replaced REE with elements that are less expensive and readily available. The results were published in the online technical journal “Scientific Reports”.

The starting point for IWM researchers Wolfgang Körner, Georg Krugel, and Christian Elsässer was a neodymium-iron-nitrogen compound based on a type of...

Im Focus: Atomic precision: technologies for the next-but-one generation of microchips

In the Beyond EUV project, the Fraunhofer Institutes for Laser Technology ILT in Aachen and for Applied Optics and Precision Engineering IOF in Jena are developing key technologies for the manufacture of a new generation of microchips using EUV radiation at a wavelength of 6.7 nm. The resulting structures are barely thicker than single atoms, and they make it possible to produce extremely integrated circuits for such items as wearables or mind-controlled prosthetic limbs.

In 1965 Gordon Moore formulated the law that came to be named after him, which states that the complexity of integrated circuits doubles every one to two...

Im Focus: Researchers demonstrate size quantization of Dirac fermions in graphene

Characterization of high-quality material reveals important details relevant to next generation nanoelectronic devices

Quantum mechanics is the field of physics governing the behavior of things on atomic scales, where things work very differently from our everyday world.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Networking 4.0: International Laser Technology Congress AKL’16 Shows New Ways of Cooperations

24.05.2016 | Event News

Challenges of rural labor markets

20.05.2016 | Event News

International expert meeting “Health Business Connect” in France

19.05.2016 | Event News

 
Latest News

Better combustion for power generation

31.05.2016 | Power and Electrical Engineering

Stick insects produce bacterial enzymes themselves

31.05.2016 | Life Sciences

In a New Method for Searching Image Databases, a Hand-drawn Sketch Is all it Takes

31.05.2016 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>