Turbulence in the Wave Boundary Layer

General context of the study : 

Ocean waves directly impact the turbulence in the lower part of the atmosphere. This region impacted is

called the wave boundary layer (WBL). The international height for wind and turbulence measurements is 10

meters. The WBL often reaches over 100 meters in height, therefore these measurements are often within the

WBL itself and therefore strongly influenced by the ocean’s waves [Chalikov and Belevich, 1993]. If the impact

of the ocean waves is not considered when handling analysis of captured wind data, the results can be skewed to

misrepresent the true behavior of the atmosphere in applications such as weather forecasting and site assessment

for offshore wind energy. The latter aspect can be visualized by recognizing that offshore wind turbines typically

have a hub height around 150 meters, causing their blades to sweep in and out of the WBL.

The goal of this project is to work synergistically with France Energies Marines and install additional

instruments on their platform DRACCAR to capture fully the effect of the ocean surface waves on the turbulence

in the wave boundary layer. Specifically, the spectrum of the ocean surface waves is imprinted on the WBL

turbulence spectrum, in both aspects of time and space. Simultaneously, regional simulations of the Fécamp

Wind Farm will be run that attempt to capture the WBL numerically. The experimental data will then be

compared to the modelling outputs and said comparison will be used to improve the current models of the

air-sea interface and the lower atmosphere.

Detailed research program : 

Motivated by the aforementioned current limitations of the understanding of the wave boundary layer, the

proposed thesis will effect the following studies, using the expected data to be collected and regional model

outputs :

— A study determining the applicability of Monin-Obukhov Similarity Theory at the Fécamp site (similar

to work of [Ortiz-Suslow et al., 2021]).

— A study that focuses on a case study around synoptic conditions, such as the during the passage of cyclones

and its effect on the WBL turbulence (similar to that of [Huang et al., 2021]).

— Take turbulence data from mast measurements to more accurately inject turbulence into the DOROTHY

model, for numerical experimentation.

— Investigate and develop more accurate local scale parameterisations (<1 km) from mast data and integrate

into WRF

— To compare and contrast with prior parameterisations and make connections between local and

regional scales

— Compare higher resolution WRF runs with new parameterisations to satellite datasets (to compare

spatial representation)

— Use integrated parameterizations in WRF to run local scale wind farm simulations

Different steps of the work :

1. Bibliography on wave boundary layer and air-sea coupling in regional models.

2. Assist in the experimental setup and maintenance of instruments (FEM/DRACCAR).

3. Compile and run regional atmospheric, oceanic, and wave models in an HPC environment (CRIANN).

4. Programmatic analysis of the observation and modelled data.

5. Writing scientific publications and participation to an international conference.

Références : 

[Chalikov and Belevich, 1993] Chalikov, D. V. and Belevich, M. Y. (1993). One-dimensional theory of the wave

boundary layer. Boundary-Layer Meteorology, 63(1–2) :65–96.

[Huang et al., 2021] Huang, J., Zou, Z., Zeng, Q., Li, P., Song, J., Wu, L., Zhang, J. A., Li, S., and Chan, P.-w.

(2021). The turbulent structure of the marine atmospheric boundary layer during and before a cold front.

Journal of the Atmospheric Sciences, 78(3) :863–875.

[Ortiz-Suslow et al., 2021] Ortiz-Suslow, D. G., Kalogiros, J., Yamaguchi, R., and Wang, Q. (2021). An evalua-

tion of the constant flux layer in the atmospheric flow above the wavy air-sea interface. Journal of Geophysical

Research : Atmospheres, 126(8).

Le Laboratoire Ondes et Milieux Complexes est une unité mixte de recherche CNRS (UMR 6294) de l’Université Le Havre Normandie. Le LOMC compte une quarantaine d’enseignants-chercheurs/chercheurs permanents travaillant dans de nombreux domaines liés à l’ingénierie des systèmes énergétiques en général et des énergies marines en particulier, la mécanique des fluides, l’acoustique sous-marine et environnementale, l’évaluation et le contrôle non destructif par ultrasons, les métamatériaux acoustiques, la mécanique des matériaux, les matériaux composites, le génie civil et côtier, l’imagerie et l’environnement.

The desired candidate has a strong understanding of the atmospheric surface layer, air-

sea interaction, and turbulent exchange. They will have both experimental and numerical

interests and feel comfortable using and compiling scientific code in an HPC environment.

Interest in renewable energy is a plus.