Her PhD thesis "Surface and Deep Circulation off South Africa: Agulhas Leakage Influence on the Meridional Overturning Circulation During the Last 345 kyr" presented data on a major ocean current in the southern hemisphere, the Agulhas Current, which transports warm waters from the tropical Indian Ocean to the southern tip of Africa.
These new data profiles are not yet fully exploited and need to be implemented in global ocean models. But they do provide for the first time robust evidence in support of the hypothesis that the Agulhas water "leakage" into the Atlantic contributes to the strength of the Atlantic Ocean circulation at large, and the Gulf Stream in particular and therefore can stabilise or destabilise climate in Europe. This knowledge will improve predictive capabilities which aim to project future climate developments in the North Atlantic region under global climate warming scenarios, such as those employed by the Intergovernmental Panel on Climate Change (IPCC).
The Agulhas Current influences rainfall patterns and weather systems in southern Africa. A part of the warm waters are transported around South Africa into the South Atlantic and influence the ocean circulation of the entire Atlantic Ocean. Climate models predict that the amount of this water "leakage" from the Indian Ocean into the Atlantic may in fact strengthen or weaken the Gulf Stream in the North Atlantic with consequences for climate in Europe, including the Iberian Peninsula. Measurements in the ocean so far have not permitted to test if a connection between the Agulhas Current around South Africa and the climate in Europe indeed exists.
For her project, Martínez-Méndez used stable isotope gas mass spectrometry and inductively coupled plasma mass spectrometry to analyse isotopic and chemical components in the sediments underneath the Agulhas Current which document variations of this current in the past. The data profiles document that systematic changes occurred in the Agulhas Current which were directly connected with global climate changes. A combination of temperature sensitive isotopes and trace elements which are preserved in the shells of marine micro-plankton indicate that under cold climatic conditions such as the ice ages, when the rest of the world dramatically cooled, the influence of the Agulhas Current strengthened and the oceans around South Africa warmed. Ocean warming is documented also by the high abundance of tropical plankton which was preserved in the seafloor sediments. When global climate began to warm at the end of cold periods, the Agulhas Current initially became stronger and then abruptly weakened to assume a strength similar to that of today.
The implications from this research are that the flow of water coming from the tropical Indian Ocean can occasionally form a warm water pool at the southern tip of Africa. Under appropriate conditions, this water is abruptly released into the Atlantic Ocean. Because these waters also have high concentrations of salt they ultimately stimulate a density anomaly in the South Atlantic which triggers internal waves in the deep water and ultimately influence the Gulf Stream in the north.
This past December, Gema Martínez-Méndez presented the results of her PhD project at the General Assembly Fall Meeting of the AGU in San Francisco. The conference was attended by more than 12,000 researchers from the Earth Sciences worldwide representing a diverse range of expertise such as geophysics, meteorology, geochemistry, glaciology, oceanography and climatology. Out of over 16,000 research presentations, ICTA researcher Gema Martínez-Méndez's paper was chosen as one of the best student presentations and she was awarded with the 2008 AGU Fall Meeting Outstanding Student Presentation Award.
Maria Jesus Delgado | EurekAlert!
Further reports about: > AGU > Agulhas Current > Atlantic > Climate > Gulf Stream > Indian Ocean > Pacific Ocean > STREAM > global climate changes > global climate warming scenarios > global warming > marine micro-plankton > ocean circulation > southern hemisphere > temperature sensitive isotopes > water leakage
Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie
Modeling magma to find copper
13.01.2017 | Université de Genève
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Power and Electrical Engineering
18.01.2017 | Materials Sciences
18.01.2017 | Life Sciences