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Accueil > Actualités > Séminaires > Séminaires 2018

Mardi 27 février 2018 à 11h00 en salle K118

M. Gacic, A. Rubino, V. Kovacevic, M. Menna, G. Civitarese, Université de Trieste

Titre/Title : Decadal and climatic variability of the Ionian circulation pattern - interaction with dense water source(s)

Contact : Joel Sommeria (Equipe MEIGE)

Résumé/Abstract : Ionian Sea flow field shows decadal inversions of the sub-basin circulation pattern. These inversions have been explained in terms of the feedback mechanism between the Adriatic or only in one occasion Aegean Sea, and the Ionian. Long-term variations of the dense water formed in the Adriatic are generated by the varying circulation patterns in the Ionian, which then bring into the Adriatic saltier or fresher water. The deep water density changes mainly determined by the salinity, on its turn cause the inversion of the Ionian circulation. Therefore, we sustain that the Ionian circulation inversions are only due to internal mechanism. Associated with the Ionian circulation inversions, we noticed long-term variations in the mesoscale activity in the same area. Pelops Gyre one of the most persistent, bottom trapped mesoscale anticyclone in the area, is very prominent during the last three decades except during the Eastern Mediterranean Transient (EMT) when the bottom water in the Ionian was mainly of the Aegean origin. In that period (1992-1997) as seen from altimetric data, the Ionian sub-basin scale circulation pattern was anticyclonic and instead of the Pelops anticyclone, the area along the eastern Ionian coast was characterized by a cyclonic mesoscale activity. After the year 2000, Adriatic became again the main bottom water source for the Ionian and the Eastern Mediterranean, and during the anticyclonic Ionian circulation mode (2007-2011) the cyclonic mesoscale activity is mainly present along the western Ionian coast, while the Pelops Gyre was very prominent. Thus, the mesoscale cyclonic activities occurs downstream of the dense water outflow (Aegean – eastern Ionian flank or Adriatic – western Ionian flank) as shown also in the laboratory experiment by Etling et al. (2000).

We present also numerical simulation results performed using a multilayer frontal model to elucidate aspects of the dynamics mentioned above in the Adriatic as well as in the Ionian basin.