Les écoulements géophysiques dans l’océan et l’atmosphère sont caractérisés par : 
des nombres de Reynolds très élevés une stratification en densité l’influence de la rotation terrestre
Notre approche consiste d’une part à utiliser les modèles numériques et théoriques développés depuis de nombreuses années au sein de l’équipe Turbulence et Instabilités pour comprendre la dynamique des écoulements turbulents géophysiques, et d’autre part à tirer profit des observations in situ, qui correspondent à des régimes de turbulence inaccessibles en laboratoire ou dans les simulations numériques, pour tester la validité de nos développements théoriques.
Au cours des dernières années, l’avancée des technologies ont rendu possible l’exploration d’environnements extrêmes comme les océans profonds, les atmosphères planétaires, l’héliosphère et le soleil. Grâce à l’évolution
du calcul haute performance et aux résolutions sans précédent obtenues par les instruments modernes de détection "in situ" et à la télédétection, la recherche sur la mécanique des fluides appliquée aux écoulements géophysiques joué un rôle indispensable dans la vérification des théories de la turbulence et la confirmation des prévisions de la mécanique statistique. Nous menons une approche synergique qui allie simulations numériques, missions d’observation, expériences de laboratoire et modélisations théoriques. Ceci permet de déboucher sur des applications d’ingénierie présentant des avantages pour la société comme, par exemple
le développement de modèles de climat et de météo spatiale à haute résolution, l’amélioration de dispositifs de mesure fondés sur des technologies d’onde sonores et électromagnétiques à usage civil et scientifique (radar, lidar, sondes à ultrasons, satellites de télécommunications).
Les principaux sujets d’investigation de l’équipe "turbulence et d’instabilité" en mécanique des fluides appliquée aux fluides géophysiques concernent : la modélisation des cascades turbulentes l’intermittence les ondes et les instabilités la paramétrisation du mélange turbulent
Modélisation des cascades turbulentes en géophysique
Inverse cascades and resonant triads in rotating and stratified turbulence
Dual constant-flux energy cascades to both large scales and small scales
Waves and vortices in the inverse cascade regime of stratified turbulence with or without rotation
Article dans Phys. Fluids (2017)
Inverse cascades and resonant triads in rotating and stratified turbulence
D. Oks, P. D. Mininni, R. Marino, and A. Pouquet
Kraichnan’s seminal ideas on inverse cascades yielded new tools to study common phenomena in geophysical turbulent flows. In the atmosphere and the oceans, rotation and stratification result in a (...)
Article dans Phys. Fluids (2017)
Dual constant-flux energy cascades to both large scales and small scales
A. Pouquet, R. Marino, P. D. Mininni, and D. Rosenberg
In this paper, we present an overview of concepts and data concerning inverse cascades of excitation towards scales larger than the forcing scale in a variety of contexts, from two-dimensional (...)
Article dans J. Fluid Mech. (2016)
Waves and vortices in the inverse cascade regime of stratified turbulence with or without rotation
Corentin Herbert, Raffaele Marino, Duane Rosenberg & Annick Pouquet
We study the partition of energy between waves and vortices in stratified turbulence, with or without rotation, for a variety of parameters, focusing on the behaviour of the waves and vortices in (...)
Intermittence
Overview of and first observations from the TILDAE High-Altitude Balloon Mission
Distinguishing turbulent overturns in high-sampling-rate moored thermistor string observations
Characterizing turbulent overturns in CTD-data
Article dans Atmos. Meas. Tech. (2017)
Overview of and first observations from the TILDAE High-Altitude Balloon Mission
Bennett A. Maruca, Raffaele Marino, David Sundkvist, Niharika H. Godbole, Stephane Constantin, Vincenzo Carbone, and Herb Zimmerman
Though the presence of intermittent turbulence in the stratosphere has been well established, much remains unknown about it. In situ observations of this phenomenon, which have provided the (...)
Article dans J. Mar. Res. (2015)
Distinguishing turbulent overturns in high-sampling-rate moored thermistor string observations
Hans van Haren & Louis Gostiaux
Turbulent overturns are distinguished from salinity-compensated intrusions in high-resolution moored thermistor string observations. The buoyancy frequency N is used to make the time (...)
Article dans Dyn. Atmos. Ocean. (2014)
Characterizing turbulent overturns in CTD-data
Hans van Haren & Louis Gostiaux
We are concerned with the shape of overturns due to irreversible effects of turbulent mixing through internal wave breaking in the ocean. Vertical $(z)$ overturn displacements $(d)$ are computed (...)
Ondes et instabilités
Extremely long Kelvin‐Helmholtz billow trains in the Romanche Fracture Zone
Generation of internal solitary waves by frontally forced intrusions in geophysical flows
Supercritical dead water : effect of nonlinearity and comparison with observations
Weakly nonlinear propagation of small-wavelength, impulsive acoustic waves in a general atmosphere
Where large deep‐ocean waves break
Article dans Geophys. Res. Lett. (2014)
Extremely long Kelvin‐Helmholtz billow trains in the Romanche Fracture Zone
Hans van Haren, Louis Gostiaux, Eugene Morozov & Roman Tarakanov
In the Atlantic Ocean, the densest water mass Antarctic Bottom Water “AABW” can only cross the Mid‐Atlantic Ridge from its southwestern to northeastern basins in limited, because deep, conduits. At (...)
Article dans Nature Communications (2016)
Generation of internal solitary waves by frontally forced intrusions in geophysical flows
Daniel Bourgault, Peter S. Galbraith, Cédric Chavanne
Internal solitary waves are hump-shaped, large-amplitude waves that are physically analogous to surface waves except that they propagate within the fluid, along density steps that typically (...)
Article dans Wave Motion (2017)
Weakly nonlinear propagation of small-wavelength, impulsive acoustic waves in a general atmosphere
J.F. Scott, P. Blanc-Benon, O. Gainville
Multiple-scale asymptotic analysis is applied to small-wavelength, weakly nonlinear propagation of an impulsive acoustic wave in a general (3D, in-motion and time dependent) atmosphere. In (...)
Article dans J. Fluid Mech. (2016)
Supercritical dead water : effect of nonlinearity and comparison with observations
John Grue, Daniel Bourgault, Peter S. Galbraith
Supercritical ship internal wave wakes with $Fr=U/c_0\sim4–12$ (where $U$ is the ship speed and $c_0$ is the linear internal long-wave speed) are calculated by a strongly nonlinear two-layer model (...)
Article dans Geophys. Res. Lett. (2015)
Where large deep‐ocean waves break
Hans van Haren, Andrea Cimatoribus & Louis Gostiaux
Underwater topography like seamounts causes the breaking of large “internal waves” with associated turbulent mixing strongly affecting the redistribution of sediment. Here ocean turbulence is (...)
Mélange turbulent en géophysique
Scaling laws for mixing and dissipation in unforced rotating stratified turbulence
Comparison of Ellison and Thorpe scales from Eulerian ocean temperature observations
Convective mixing by internal waves in the Puerto Rico Trench
Vertical drafts and mixing in stratified turbulence : Sharp transition with Froude number
Article dans J. Fluid Mech. (2018)
Scaling laws for mixing and dissipation in unforced rotating stratified turbulence
Annick Pouquet, Duane Rosenberg, Raffaele Marino and Corentin Herbert
We present a model for the scaling of mixing in weakly rotating stratified flows characterized by their Rossby, Froude and Reynolds numbers , $Ro$, $Fr$, $Re$. This model is based on (...)
Article dans J. Geophys. Res. C (2014)
Comparison of Ellison and Thorpe scales from Eulerian ocean temperature observations
Andrea A. Cimatoribus, Hans van Haren & Louis Gostiaux
Ocean turbulence dissipation rate is estimated either by means of microstructure shear measurements, or by adiabatically reordering vertical profiles of density. The latter technique leads to the (...)
Article dans J. Mar. Res. (2016)
Convective mixing by internal waves in the Puerto Rico Trench
Hans van Haren & Louis Gostiaux
A 2.4 km long deep-sea mooring was deployed for 14 months in the Puerto Rico Trench, the deepest part of the Atlantic Ocean. Below its top buoyancy package, the mooring line held a 200 m long (...)
Article dans Europhys. Lett. (2018)
Vertical drafts and mixing in stratified turbulence : Sharp transition with Froude number
Fabio Feraco, Raffaele Marino, Alain Pumir, Leonardo Primavera, Pablo D. Mininni, Annick Pouquet & Duane Rosenberg
We investigate the large-scale intermittency of vertical velocity and temperature, and the mixing properties of stably stratified turbulent flows using both Lagrangian and Eulerian fields from (...)
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