The projects currently underway on the Coriolis Platform are moving towards an increasingly high degree of realism, of which the HERCULES project is a prime example. The specific know-how in scaling up specific processes to similarity, combined with the experience of the technical staff and state-of-the-art instrumentation, means that experimental modelling now leads to a coverage of dynamics comparable to numerical experiments, even in realistic configurations. This represents a paradigm shift.
The HERCULES project is being carried out in collaboration with SHOM and LOPS, which are contributing observational data and expertise in numerical simulation. By combining experimental data with theoretical, numerical and observational models, the platform provides a unique basis for studying small-scale processes, non-hydrostatic effects and their feedback on large scales. This approach enables key parameters to be varied systematically, providing generalisable results that can be used to calibrate sub-grid parameterisations in numerical and climate models. These data are also crucial for training artificial intelligence (AI) and for developing diagnostic tools for non-linear processes in geophysics, such as mixing and turbulence, which are at the base of spontaneous climate fluctuations.
(figure 1 : Sketch of the experimental set up and forcings used)
Some of the studied aspects are :
Hydraulics and dynamics in the Strait
(figure 2 : Depth of the Mediterranean outflow around camarinal durin three tidal cycles of a Spring tide experiment, highlighting the control formation downstream of the slope and its lost and propagation toward the east during inflow. This is the phenomenon at the base of the formation of internal solitary waves in the Strait)
Internal waves
(figure 3 : two types of waves are observed : bores and solitons. A model to predict them has been obtained based on the local criticality of the flow. From the work of the PhD Axel Tassigny)
turbulent fluxes and mixing
(figure 4 : variations of the density in the full water column (700m) up to 15-20% depending on the tidal phase, in accord with in situ data)
dynamics of the Mediterranean Outflow in the Gulf of Cadiz (figure 5, 6, 7)
(figure 5 : Transects of MOW speed at the outlet of the Strait and further downstream along the Portugal coast. From the work of the Post-Doc Stef Bardoel)
(figure 6 : Vortex detection at 160m depth in the Gulf of Cadiz using the AMEDA Toolbox.From the work of the Post-Doc Stef Bardoel)
(figure 7 : Visualization of the Mediterranean Outflow through the main channels in the southern part of the Gulf of Cadiz)
Référence complémentaire :
Vidéo réalisée par le CNRS en collaboration avec le Monde https://www.lemonde.fr/sciences/video/2023/11/10/plongee-dans-le-detroit-de-gibraltar-en-modele-reduit_6199341_1650684.html