CFD Online Logo CFD Online URL
Home > Jobs > Job Record #16990

CFD Jobs Database - Job Record #16990

Job Record #16990
TitlePhD in ocean turbulence
CategoryPhD Studentship
EmployerUnité de Mécanique de Lille
LocationFrance, Lille
InternationalYes, international applications are welcome
Closure DateSaturday, May 15, 2021
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. 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.

Work plan and goal 
In this thesis, inscribed in the CNES research project “DIEGO: Data and dynamical synergies for SWOT”, we 
will explore Lagrangian transport in models of surface ocean turbulence including ageostrophic dynamics by 
means of numerical simulations. In particular, we will focus on the role of the effective compressibility 
characterizing the 2D surface flows at scales of order 1 km, which is directly related to important vertical 
velocities. The research work will mainly rely on idealized simulations. Using the SWOT simulator software 
with the numerically computed flows, it will be possible to examine the effect of the data processing that will 
be applied to the real observations. Depending on the advancement of the project it could also be possible to 
use realistic high-resolution models, as well as the satellite data when available. The analysis will be based 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.

Research team
The PhD thesis (starting in October 2021) will be conducted at UML, Lille, in tight collaboration with G. 
Lapeyre at LMD, ENS, Paris. It will also benefit from regular meetings with the staff of LOPS, Brest, involved 
on other workpackages of project DIEGO.

Candidate having good knowledge of fluid mechanics or dynamical systems and an interest for numerical 
methods; education: Master in Fluid Mechanics, Physics, Geophysical Fluid Dynamics, Applied Mathematics. 
Good knowledge of oral and written English is required. Knowing Fortran, Python or Matlab would be a plus.

Interested candidates should send their CV, a letter of motivation, and possibly contact information of two 
Contact Information:
Please mention the CFD Jobs Database, record #16990 when responding to this ad.
NameStefano Berti
Email ApplicationYes
Record Data:
Last Modified17:12:40, Tuesday, February 23, 2021

[Tell a Friend About this Job Advertisement]

Go to top Go to top