Proposition de sujet de stage de Master 2 pour 2022 = Attention le stage est pourvu
Titre du stage :
Analysis of boundary layer flow modification in coral forests: canopy effect quantification
Encadrants :
Katell Guizien (LECOB, OOB, CNRS) -Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser.
Lieu du stage :
LECOB UMR822, Observatoire Océanologique de Banyuls, Sorbonne Université – CNRS, 66650 Banyuls-sur-Mer.
Description et objectif scientifique :
When ocean beds are covered by large obstacles, the classical boundary layer structure is significantly modified. The wakes produced by these obstacles create strong spatial variations in the flow, over a region (embedded within the boundary layer) known as the roughness sublayer (Ghisalberti 2009). Long-lived hard and soft coral species that are able to develop dense patches with a complex, three-dimensional structure form an animal forest canopy (sensu Rossi et al 2017), similar to trees in terrestrial systems (Ghisalberti and Nepf, 2002). Aside from the shelter provided by this canopy to other organisms, the animal forest can significantly modify the local physical and biogeochemical environment (reviewed in Guizien and Ghisalberti, 2017). Flow velocity profiles were measured with a high-resolution Doppler profiler across the 2 meters above the bottom in locations covered by soft corals at differents population densities. In shallow locations, the flow was dominated by waves (oscillatory flow) and in deep locations, by current (steady flow). The objective of the internship is to analyse the near-bottom flow velocity profile measurements with various signal processing methods developping customed Matlab routines in order to quantify the animal forest canopy effect on the flow (steady and unsteady) and test wether it can be related to any animal forest descriptors (height, population density). In the case of steady flows, canopy descriptors as established for atmospherical urban canopies will be considered (Mac Donald, 2000).
Analysis of boundary layer flow modification in coral forests: canopy effect quantification
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