2023-05-08 13:45:55
The AMOC (Atlantic Meridional Overturning Circulation) is a set of currents in the Atlantic Ocean involved in the distribution of heat, carbon and nutrients. This transport is carried out horizontally and also vertically, but with different speeds; the verticals are much smaller in magnitude than the horizontals, making the measurement and direct observation of transport difficult by tracers, floats, or other techniques.
Now, in Spain, scientists from the Institute of Mathematical Sciences (ICMAT, attached to the Higher Council for Scientific Research (CSIC), the Autonomous University of Madrid (UAM), the Carlos III of Madrid (UC3M) and the Complutense of Madrid (UCM) ), together with scientists from the Polytechnic University of Catalonia (UPC), have applied a new methodology to describe this vertical transport, which is crucial for understanding how large masses of water and heat move and how the processes of removing dioxide work. carbon (CO2) from the atmosphere.
The AMOC is one of the great circulation systems of the ocean and has deep connections to marine ecosystems and across the planet. In the North Atlantic it is made up of warm surface currents, which flow north, and deep cold currents, which move south. These circulation currents connect with each other in the turning or inversion zones in the Nordic and Labrador seas.
“The sinking of these masses of water has been studied more, but it is not so evident how and where the masses of water rise again, something necessary to keep the system of currents circulating,” explains Ana María Mancho, a CSIC researcher at ICMAT. .
“We have located areas of the AMOC in the North Atlantic where ascension processes take place in much shorter times than those characterized up to now”, comments Mancho. “Thanks to this methodology, something as complicated as transport can be understood in an orderly fashion based on geometric structures that make up Lagrangian Coherent Structures (LCS)”, he continues.
A coastal sector of the North Atlantic. (Photo: SeaWiFS Project, NASA Goddard Space Flight Center / ORBIMAGE)
Lagrangian descriptors are a tool that allows to identify the so-called Lagrangian coherent structures, which determine the transport barriers associated with currents. This approach makes it possible to identify areas of the ocean with masses of water that are transported in a similar way. “For example, it makes it possible to easily distinguish masses of water that remain within a current for a long time from those that do not, and also barriers or critical regions that correspond to areas of the ocean with masses of water that progress very differently,” he comments. mancho.
The researcher Ana María Mancho has directed the work together with Jezabel Curbelo, a Ramón y Cajal researcher at the UPC and Mancho’s former doctoral student at the ICMAT. Both had applied this methodology in a study of the West African monsoon, a three-dimensional convective system. “So we saw that it could be very useful to understand the transport in the AMOC, which is also a system of this type”, explains Mancho.
The working group is completed by Guillermo García Sánchez, CSIC predoctoral researcher at ICMAT, and Renzo Bruera, FPU predoctoral researcher at the UPC.
The study is titled “Mixing and Geometry in the North Atlantic Meridional Overturning Circulation”. And it has been published in the academic journal Geophysical Research Letters. (Source: ICMAT / CSIC)
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