Towards a better representation of ocean dynamics through a better knowledge of multi-scale processes

Topic 2

 

This topic focuses on the description of multi-scale processes and their interactions, with the aim of deriving a better description of ocean dynamics. The interaction of wave processes with ocean dynamics at different scales is a line of research in this topic. As an example, the influence of gravity waves transformation on the dynamics of coastal zones and beach aquifers is investigated. More generally, the interaction between marine circulation and waves is still poorly represented in models. Hence, wave-induced circulation and the feedback influence of water currents on wave propagation (coupling) are good examples of multi-scales interactions that must be integrated in ocean models used to investigate ocean dynamics in coastal zones.

On the one hand, a good knowledge and a realistic representation in circulation models of multi-scale ocean dynamics is required before studying marine ecosystems and/or environmental issues that are associated with the ocean (cf topic 3). On the other hand, the retroaction of biogeochemistry (especially light absorption by chlorophyll) on heat budgets and ocean dynamics is still poorly quantified and not represented in one-way coupled physical-biogeochemical models even though this effect seems far from negligible.

In this context, another line of research in this topic aims at studying the effects of ocean dynamics and especially (sub)-mesoscale dynamics on the variability of currents, coast-offshore exchanges, energy and mass fluxes, and hydrological and biogeochemical tracers. For this purpose, in-situ measurements with specific protocols (Lagrangian tracking, ect...) are combined with numerical modelling. This combined approach is used at the basin (Mediterranean, Pacific Ocean) and regional scales (north western Mediterranean), and for the study of specific ecosystems such as lagoon-reefs, with a focus on the influence of terrigenous, cross-reef and coast-offshore fluxes, island plumes or upwelling regions.