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| García-ibáñez, Maribel I.; Bates, Nicholas R.; Bakker, Dorothee C.e.; Fontela, Marcos; Velo, Antón. |
| The net uptake of carbon dioxide (CO2) from the atmosphere is changing the ocean's chemical state. Such changes, commonly known as ocean acidification, include a reduction in pH and the carbonate ion concentration ([CO32−]), which in turn lowers oceanic saturation states (Ω) for calcium carbonate (CaCO3) minerals. The Ω values for aragonite (Ωaragonite; one of the main CaCO3 minerals formed by marine calcifying organisms) influence the calcification rate and geographic distribution of cold-water corals (CWCs), important for biodiversity. Here, high-quality measurements, collected on thirteen cruises along the same track during 1991–2018, are used to determine the long-term changes in Ωaragonite in the Irminger and Iceland Basins of the North Atlantic... |
| Tipo: Text |
Palavras-chave: Ocean acidification; Aragonite saturation state; Atlantic Meridional Overturning Circulation; Eastern-Subpolar North Atlantic Ocean. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/79965/82895.pdf |
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| Talandier, Claude; Deshayes, Julie; Treguier, Anne-marie; Capet, Xavier; Benshila, Rachid; Debreu, Laurent; Dussin, Raphael; Molines, J. -m.; Madec, Gerard. |
| Previous studies have shown that low horizontal resolution (of the order of 1°) ocean models, hence climate models, are not able to adequately represent boundary currents nor mesoscale processes which affect the dynamics and thermohaline circulation of the ocean. While the effect of mesoscale eddies can be parameterized in low resolution models, boundary currents require relatively high horizontal resolution. We clarify the impact of increasing the resolution on the North Atlantic circulation, with emphasis on the Atlantic Meridional Overturning Circulation (AMOC), by embedding a 1/8° nest covering the North Atlantic into a global 1/2° model. Increasing the resolution in the nest leads to regional improvements of the circulation and thermohaline... |
| Tipo: Text |
Palavras-chave: Deep Western Boundary Current; Atlantic Meridional Overturning Circulation; North Atlantic Current; Gulf Stream; Subpolar gyre. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00173/28472/26812.pdf |
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| Lippold, Jorg; Gherardi, Jeanne Marie; Luo, Yiming. |
| Variations of the Atlantic Meridional Overturning Circulation (AMOC) are believed to have crucially influenced Earth's climate due to its key role in the inter-hemispheric redistribution of heat and carbon. To assess its past strength, the sedimentary Pa-231/Th-230 proxy has been developed and improved but also contested due to its sensitivity to other factors beyond ocean circulation. In order to provide a better basis for the understanding of the Atlantic Pa-231/Th-230 system, and therefore to shed light on the controversy, we compare new measurements of Holocene sediments from the north Brazilian margin to water column data and the output of a two-dimensional scavenging-circulation model, based on modern circulation patterns and reversible scavenging... |
| Tipo: Text |
Palavras-chave: 231Pa/230Th; Atlantic Meridional Overturning Circulation; Holocene; Deep sea sediments. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00215/32576/31045.pdf |
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| Lippold, Jorg; Gutjahr, Marcus; Blaser, Patrick; Christner, Emanuel; Ferreria, Maria Luiza De Carvalho; Mulitza, Stefan; Christl, Marcus; Wombacher, Frank; Böhm, Evelyn; Antz, Benny; Cartapanis, Olivier; Vogel, Hendrik; Jaccard, Samuel L.. |
| Reconstructing past modes of ocean circulation is an essential task in paleoclimatology and paleoceanography. To this end, we combine two sedimentary proxies, Nd isotopes (epsilon(Nd)) and the Pa-231/Th-230 ratio, both of which are not directly involved in the global carbon cycle, but allow the reconstruction of water mass provenance and provide information about the past strength of overturning circulation, respectively. In this study, combined Pa-231/Th-230 and epsilon(Nd) down-core profiles from six Atlantic Ocean sediment cores are presented. The data set is complemented by the two available combined data sets from the literature. From this we derive a comprehensive picture of spatial and temporal patterns and the dynamic changes of the Atlantic... |
| Tipo: Text |
Palavras-chave: Pa-231/Th-230; Epsilon(Nd); Atlantic Meridional Overturning Circulation; Deep sea sediments; Last Glacial Maximum; Deglaciation. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53236/54762.pdf |
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| Zhang, Xiao. |
| v Abstract This thesis focused on the Atlantic Meridional Overturning Circulation (AMOC) stability and global climate responses of an altered AMOC in the late Neogene by performing computer simulations, using both intermediate complexity climate models and state-of-the-art coupled climate models. Two time slices were studied: 1) 38 ka BP (kilo years before present), during Heinrich event 4, and 2) around 4- 5 million years ago, when the Panamanian Seaway finally gradually closed. The AMOC is one of the most important climate systems modulating the world climate due to the significant amount of oceanic transport of heat, carbon and nutrients. Understanding the AMOC stability behaviour is essential to investigate climate in the past and present as well as... |
| Tipo: Text |
Palavras-chave: Atlantic Meridional Overturning Circulation; Climate instability; State-of-the-art model simulation. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00505/61710/65679.pdf |
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