Profiling float observation of thermohaline staircases in the western Mediterranean Sea and impact on nutrient fluxes - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Biogeosciences Année : 2020

Profiling float observation of thermohaline staircases in the western Mediterranean Sea and impact on nutrient fluxes

Résumé

In the western Mediterranean Sea, Levantine intermediate waters (LIW), which circulate below the surface productive zone, progressively accumulate nutrients along their pathway from the Tyrrhenian Sea to the Algerian Basin. This study addresses the role played by diffusion in the nutrient enrichment of the LIW, a process particularly relevant inside step-layer structures extending down to deep waters-structures known as thermohaline staircases. Profiling float observations confirmed that staircases develop over epicentral regions confined in large-scale circulation features and maintained by saltier LIW inflows on the periphery. Thanks to a high profiling frequency over the 4-year period 2013-2017, float observations reveal the temporal continuity of the lay-ering patterns encountered during the cruise PEACETIME and document the evolution of layer properties by about + 0.06°C in temperature and +0.02 in salinity. In the Al-gerian Basin, the analysis of in situ lateral density ratios untangled double-diffusive convection as a driver of thermoha-line changes inside epicentral regions and isopycnal diffusion as a driver of heat and salt exchanges with the surrounding sources. In the Tyrrhenian Sea, the nitrate flux across ther-mohaline staircases, as opposed to the downward salt flux, contributes up to 25 % of the total nitrate pool supplied to the LIW by vertical transfer. Overall, however, the nutrient enrichment of the LIW is driven mostly by other sources, coastal or atmospheric, as well as by inputs advected from the Algerian Basin.

Domaines

Océanographie
Fichier principal
Vignette du fichier
bg-17-3343-2020.pdf (8.02 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

hal-02961877 , version 1 (09-10-2020)

Licence

Paternité - Pas de modifications

Identifiants

Citer

Vincent Taillandier, Louis Prieur, Fabrizio d'Ortenzio, Maurizio Ribera d'Alcalà, Elvira Pulido-Villena. Profiling float observation of thermohaline staircases in the western Mediterranean Sea and impact on nutrient fluxes. Biogeosciences, 2020, 17 (13), pp.3343-3366. ⟨10.5194/bg-17-3343-2020⟩. ⟨hal-02961877⟩
63 Consultations
37 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More