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 on beach aquifers are 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 current on wave propagation (coupling) is a good example of multi-scales interactions that need to be integrated in ocean model used to investigate ocean dynamics in coastal zones.

On 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 associated with ocean (cf topic 3). On the other hand, the retroaction of biogeochemistry (and 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 though this impact seems far from negligible.

In this context, another line of research in this topic aims at studying the impact of ocean dynamics and especially (sub)-mesoscale dynamics on the variability of currents, on coast-offshore exchanges, on energy and mass fluxes, as well as on hydrological and biogeochemical tracers. For this purpose, in situ measurements with specific protocols (lagrangian tracking, ...) are combined with numerical modelling. This combined approach is used not only at basin scale (Mediterranean, Pacific Ocean) or regional scale (North western Mediterranean), but also 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.