ASICS-MED

The North Western Mediterranean is prone to strong wind events that may lead – through their interaction with the upper ocean dynamics – to dense water formation. The Gulf of Lion is thereby a major key spot of dense water formation through the deep ocean convection mechanism that results from the interaction of the Northern Current with the cyclonic gyre under strong winds (Mistral, Tramontana). Although this mechanism is of crucial importance to accurately simulate both the water masses and the basin-scale thermohaline circulation, its representation in state-of-the-art ocean models remains rudimentary. The main objective of ASICS-MED is to deeply investigate the ocean-atmosphere processes that contribute to dense water formation to improve their representation in ocean models. The process studies focus on the mesoscale and sub-mesoscale that were already shown to significantly contribute to the basin scale dense water formation. The methodology is to: (i) simultaneously collecting observations in the ocean and the marine atmospheric boundary layer (MABL) over the Gulf of Lion during late winter 2013, focusing on strong wind and ocean convective events; (ii) making use of several high-resolution limited-area ocean models over the North-Western Mediterranean together with a dedicated version of the AROME atmospheric model to simulate the evolution of both the upper ocean and MABL during the preconditioning phase and the dense water formation; (iii) developing a mass-flux parameterization scheme for ocean convection and improving air-sea fluxes parameterizations; and (iv) identifying (sub)mesoscale ocean/atmosphere processes involved in the upper ocean and MABL evolution and leading to dense water formation. The ASICS-MED project will take advantage from a strong national and international collaborative environment as part of the much wider HyMeX research initiative. ASICS-MED, which will deeply contribute to a major issue in physical oceanography (namely dense water formation), should also strongly benefit to operational oceanography as well as to climate studies focusing on the interannual to decadal variability of the Mediterranean system, especially in the context of climate change.