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Job Record #16905
TitleMaster internship on oceanic turbulence
EmployerUniversité de Lille
LocationFrance, Lille
InternationalYes, international applications are welcome
Closure Date* None *
Title: Lagrangian particle dynamics at oceanic submesoscales and future satellite data

Context and goal: Ocean flows at scales larger than few tens of km are quasi-horizontal due to the 
pronounced stratification of seawater and Earth’s rotation and are characterized by quasi-2D turbulence. At 
scales around 300 km (the mesoscale range), coherent structures (almost circular vortices) contain most of 
the kinetic energy and are key for ocean dynamics at climatic scales. At scales around 10 km (the 
submesoscale range) the flow is host to smaller eddies and filaments associated with strong gradients of 
physical properties (e.g. temperature) and intense vertical transport, which play an important role in both 
physical and biogeochemical budgets. Mesoscale and submesoscale flows also shape the physical and 
chemical environment in which life develops in the ocean (Fig. 1). Direct observation of submesoscale surface 
velocity fields at global scale is still not possible but it should be achieved in the near future by the satellite 
SWOT (NASA-CNES, launch in 2022).
To compute large-scale horizontal transport, surface energy exchanges or global estimates of other 
quantities, it is crucial to assess how well the horizontal velocities provided by the satellite compare to actual 
surface currents and down to what length scale. For this purpose, Lagrangian approaches provide an ideal 
framework, as, differently from standard Eulerian ones, they integrate in time the signal. Thanks to this 
property, they may allow a clear separation between fast (ageostrophic) processes, that could contaminate 
the satellite-derived velocity, and slower (geostrophic) ones.

In this internship, funded by CNES, we will explore Lagrangian transport in a model of surface ocean 
turbulence including ageostrophic dynamics by means of numerical simulations. Using the SWOT simulator 
software with the numerically computed flows, it will be also possible to examine the effect of the data 
processing that will be applied to the real observations. The analysis will rely on the comparison of different 
statistical indicators of Lagrangian dispersion in the original and processed flows. The aim is to determine the 
effect of unresolved motions, and of the data processing procedure, on dispersion features. In particular, this 
study should allow the identification of a threshold length scale above which the approximate velocity field is 
accurate enough, at least in a statistical sense, as well as an estimate of the kinetic energy of the missing 
small scales.

Candidate: Education in Fluid mechanics, Physics, Applied Mathematics, Physical Oceanography. Good 
knowledge of fluid mechanics and an interest for numerical methods. Good knowledge of oral and written 
English is required. Knowing a programming language (Fortran, Python, Matlab) would be a plus. Interested 
candidates should send their CV and a motivation letter.

Keywords: fluid mechanics, turbulence, numerical simulations, oceanography
Contact Information:
Please mention the CFD Jobs Database, record #16905 when responding to this ad.
NameStefano Berti
Email ApplicationYes
Record Data:
Last Modified09:04:47, Tuesday, December 22, 2020

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