Séminaire
The Mediterranean Sea is a semi-enclosed sea which displays a thermohaline circulation feeding anti-estuarine exchanges at its outer strait. Many of its key circulation features occur at the mesoscale: transports at straits, subbasin circulations and deep convection. Hence its variability is highly sensitive to the chaotic mesoscale dynamics. In particular, deep convection is the main driver of thermohaline circulation through the formation and subsequent spreading of deep waters. This phenomenon is believed to be inhibited by the restratification process driven by mesoscale eddies.
The aim of this presentation is to characterize several aspects of the Mediterranean thermohaline circulation and to study how mesoscale impacts their mean properties and their variability.
For that we performed ensemble eddy-permitting (7km) and eddy-resolving (2km) Mediterranean Sea simulations over the well-documented 2012-2013 period and the historical 1979-2013 period. We will first characterize deep convection from observations during the exceptional 2012-2013 field campaign MERMEX – HyMeX in the Northwestern Mediterranean Sea. We will then address how mesoscale dynamics impacts the mean properties and the chaotic variability of deep convection in that region. We will finally assess the respective roles of the mesoscale chaotic dynamics and external forcings in the interannual variability of the Mediterranean thermohaline circulation.
felix.margirier@locean-ipsl.upmc.fr