This wave-following platform was developed by MIO researcher Denis Bourras ten years ago to study turbulent flows at the air-sea interface, in collaboration with LATMOS, LOCEAN, Ifremer, Météo-France, LOPS, IRPHE, DT-INSU and LOG. Two prototypes exist and have been deployed in various regions since 2011. The measurements obtained, mainly in swell conditions, provide a new point of view compared with measurements carried out on oceanographic vessels.
The published paper qualifies the measurements and evaluates various parameterizations used in surface atmospheric boundary layer models, from the friction coefficient to the normalized turbulence dissipation function. The data is freely available on https://erddap.osupytheas.fr/erddap/search/index.html?page=1&itemsPerPag… and https://www.seanoe.org/data/00486/59768/. The flow calculation code is also publicly available, https://gitlab.osupytheas.fr/bourras.d/albatros_public_distrib
OCARINA will continue its mission in 2020 in Barbados, as part of the EUREC4A project (project led by the LMD, S. Speich, H. Bellenger), equipped with additional instruments, including a signature ADCP and a prototype instrument for measuring capillary waves developed by IRPHE and OSU-Pytheas (C. Luneau and Hubert Branger).
"Data obtained from a wave-following platform are used to calibrate coefficients and multiple parameterisations of air-sea fluxes in swell conditions.
Turbulent fluxes are physical quantities that describe the exchanges of heat and momentum through the air-sea interface. They are critical to the processes of weather and climate change. A limited understanding of air-sea exchanges makes weather prediction difficult and lead to uncertainty in climate projection. A big challenge is the lack of efficient technology to make measurements.
Bourras et al [2019] have obtained in-situ observations on a novel wave-following platform in four oceanic regions and under different conditions. Various parameterizations for surface fluxes and related coefficients are calibrated against the observations. The authors only collected data under moderate winds, thus observations on turbulent fluxes under strong winds (such as hurricane and typhoon) still require a breakthrough."