Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 14, 1197-1213, 2017
https://doi.org/10.5194/bg-14-1197-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
13 Mar 2017
High-resolution regional modelling of natural and anthropogenic radiocarbon in the Mediterranean Sea
Mohamed Ayache1, Jean-Claude Dutay1, Anne Mouchet1, Nadine Tisnérat-Laborde1, Paolo Montagna2, Toste Tanhua3, Giuseppe Siani4, and Philippe Jean-Baptiste1 1Laboratoire des Sciences du Climat et de l'Environnement LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
2Istituto di Scienze Marine, CNR, Bologna, Italy
3GEOMAR Helmholtz Centre for Ocean Research Kiel, Dusternbrooker Weg 20, 24105 Kiel, Germany
4GEOPS Geoscience Paris Sud UMR 8148, Orsay, France
Abstract. A high-resolution dynamical model (Nucleus for European Modelling of the Ocean, Mediterranean configuration – NEMO-MED12) was used to give the first simulation of the distribution of radiocarbon (14C) across the whole Mediterranean Sea. The simulation provides a descriptive overview of both the natural pre-bomb 14C and the entire anthropogenic radiocarbon transient generated by the atmospheric bomb tests performed in the 1950s and early 1960s. The simulation was run until 2011 to give the post-bomb distribution. The results are compared to available in situ measurements and proxy-based reconstructions. The radiocarbon simulation allows an additional and independent test of the dynamical model, NEMO-MED12, and its performance to produce the thermohaline circulation and deep-water ventilation. The model produces a generally realistic distribution of radiocarbon when compared with available in situ data. The results demonstrate the major influence of the flux of Atlantic water through the Strait of Gibraltar on the inter-basin natural radiocarbon distribution and characterize the ventilation of intermediate and deep water especially through the propagation of the anthropogenic radiocarbon signal. We explored the impact of the interannual variability on the radiocarbon distribution during the Eastern Mediterranean Transient (EMT) event. It reveals a significant increase in 14C concentration (by more than 60 ‰) in the Aegean deep water and at an intermediate level (value up to 10 ‰) in the western basin. The model shows that the EMT makes a major contribution to the accumulation of radiocarbon in the eastern Mediterranean deep waters.

Citation: Ayache, M., Dutay, J.-C., Mouchet, A., Tisnérat-Laborde, N., Montagna, P., Tanhua, T., Siani, G., and Jean-Baptiste, P.: High-resolution regional modelling of natural and anthropogenic radiocarbon in the Mediterranean Sea, Biogeosciences, 14, 1197-1213, https://doi.org/10.5194/bg-14-1197-2017, 2017.
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Short summary
A high-resolution dynamical model was used to give the first simulation of the distribution of natural and anthropogenic radiocarbon (14C) across the whole Mediterranean Sea. The model correctly simulates the main features of 14C distribution during and after the bomb perturbation. The results demonstrate the major influence of the flux of Atlantic water through the Strait of Gibraltar, and a significant increase in 14C in the Aegean deep water during the Eastern Mediterranean Transient event.
A high-resolution dynamical model was used to give the first simulation of the distribution of...
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