Yannis Cuypers

Generation and propagation of internal tides and solitary waves at the shelf edge of the Bay of Biscay

High frequency mooring data were collected near the northern shelf edge of the Bay of Biscay to investigate the generation and propagation of internal tides and internal solitary waves (ISWs). During spring tide, strong nonlinear internal tides and large amplitude ISWs are observed every semi-diurnal tidal period. While onshore propagation was expected since the mooring is located shoreward of the maximum internal tidal generation location, both onshore and seaward traveling internal tides are identified. Within a tidal period at spring tide, three ISW packets are observed. Like internal tides, different ISW packets have opposite (seaward and shoreward) propagating direction. Based on realistic hydrostatic HYCOM simulations, it is suggested that advection by the barotropic tide affects wave generation and propagation significantly and is essential for the seaward traveling internal tides to appear shoreward of their generation location. A two-layer idealized non-hydrostatic model derived by Gerkema [1996] further confirms the effect of advection on the generation and propagation of internal tides. Moreover, the two-layer model reproduces one seaward propagating ISW packet and one shoreward propagating ISW packet, indicating that the offshore and onshore traveling ISWs are excited by nonlinear steepening of the seaward and shoreward traveling internal tides, respectively. This article is protected by copyright. All rights reserved.

Longitudinal contrast in Turbulence along a ∼ 19S section in the Pacific and its consequences on biogeochemical fluxes

Microstructure measurements were performed along the OUTPACE longitudinal transect in the tropical Pacific (Moutin and Bonnet, 2015). Small-scale dynamics and turbulence in the first 800m surface layer were characterized based on hydrographic and current measurements at fine vertical scale and turbulence measurements at cm scale using a vertical microstructure profiler. The possible impact of turbulence on biogeochemical budgets in the surface layer was also addressed in this region of increasing oligotrophy to the East. The dissipation rate of turbulent kinetic energy, , showed an interesting 5 contrast along the longitudinal transect with stronger turbulence in the West, i.e. the Melanesian Archipelago, compared to the East, within the South Pacific Subtropical Gyre, with a variation of by a factor of 3 within [100m−500m]. The layer with enhanced turbulence decreased in vertical extent traveling eastward. This spatial pattern was correlated with the energy level of the internal wave field, higher in the West compared to the East. The difference in wave energy mostly resulted from enhanced wind power input into inertial motions in the West. Moreover, three long duration stations were sampled along the cruise 10 transect, each over three inertial periods. The analysis from the western long duration station gave evidence of an energetic baroclinic near-inertial wave that was responsible for the enhanced , observed within a 50m-250m layer, with a value of 810−9Wkg−1, about 8 times larger than at the eastern long duration stations. Averaged nitrate turbulent diffusive fluxes in a 100-m layer below the top of the nitracline were about twice larger west of 170W due to the higher vertical diffusion coefficient. In the photic layer, the depth-averaged nitrate turbulent diffusive flux strongly decreased eastward with an 15 averaged value of 11μmolm−2d−1 West of 170W to be compared with the 3μmolm−2d−1 averaged value East of 170W. Contrastingly phosphate turbulent diffusive fluxes were significantly larger in the photic layer. This input may have an important role in sustaining the development of N2-fixing organisms that were shown to be the main primary contributors to the biological pump in the area. The time-space intermittency of mixing events, intrinsic to turbulence, was underlined but its consequences on micro-organisms would deserve a dedicated study. 20 Copyright statement.

Contrasted turbulence intensities in the Indonesian Throughflow: a challenge for parameterizing energy dissipation rate

Microstructure measurements were performed along two sections through the Halmahera Sea and the Ombai Strait and at a station in the deep Banda Sea. Contrasting dissipation rates (𝜖) and vertical eddy diffusivities (Kz) were obtained with depth-averaged ranges of ∼[9×10−10−10−5]

Focusing of internal tides by near-inertial waves

\sim [9 \times 10^{-10}-10^{-5}]

Courant géostrophique et instabilité barocline dans une cuve tournante

W kg− 1 and of ∼[1×10−5−2×10−3]

Full-depth desalination of warm sea ice

\sim [1 \times 10^{-5}-2 \times 10^{-3}]

Large‐amplitude internal tides, solitary waves, and turbulence in the central Bay of Biscay

m2 s− 1, respectively. Similarly, turbulence intensity, I=𝜖/(νN2)

Ice production in Storfjorden (Svalbard) estimated from a model based on AMSR‐E observations: Impact on water mass properties

I={\epsilon }/(\nu N^{2})

Internal waves and vertical mixing in the Storfjorden Polynya, Svalbard

with ν the kinematic viscosity and N the buoyancy frequency, was found to vary seven orders of magnitude with values up to 107

Characterization of turbulence and validation of fine-scale parametrization in the Mediterranean Sea during BOUM experiment

10^{7}