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This work serves as an observation‐based exploration into the role of wave‐driven turbulence at the air‐sea interface by measuring Turbulent Kinetic Energy (TKE) dissipation rates above and below the sea surface. Subsurface ocean measurements confirm a TKE dissipation rate enhancement relative to the predicted law‐of‐the‐wall (εobs > εp), which appears to be fully supported by wave breaking highlighting the role of the transport terms in balancing the subsurface TKE budget. Simultaneous measurements of TKE dissipation rates on the atmospheric side capture a deficit relative to the law‐of‐the‐wall (εobs < εp). This deficit is explained in terms of wave‐induced perturbations, with observed convergence to the law‐of‐the‐wall at 14 m above mean sea level. The deficit on the atmospheric side provides an estimate of the energy flux divergence in the wave boundary layer. An exponential function is used to integrate in the vertical and provide novel estimates of the amount of energy going into the wave field. These estimates correlate well with classic spectral input parameterizations and can be used to derive an effective wave‐scale, capturing wind‐wave coupling purely from atmospheric observations intimately tied to wave‐induced perturbations of the air‐flow. These atmospheric and oceanic observations corroborate the commonly assumed input‐dissipation balance for waves at wind speeds in the 8‐14 ms−1 range in the presence of developed to young seas. At wind speeds above 14 ms−1 under young seas (U10cp>1.2 $\sfrac{{U}_{10}}{{c}_{p}} > 1.2$)observations suggest a deviation from the TKE input‐dissipation balance in the wave field. Plain Language Summary: A long‐term field campaign on the Western North Atlantic shelf provided observations of Turbulent Kinetic Energy (TKE) dissipation rates on both sides of the sea surface. These observations were used to track the energy exchange between the atmosphere and ocean that is mediated by surface waves. Deviations from the expected law‐of‐the‐wall scaling in our TKE dissipation rate estimates were linked to wind energy input leading to wave growth, wave breaking and the subsequent TKE injection into the water column. Observations confirm the subsurface enhancement of TKE relative to the classic law‐of‐the‐wall and showcase a TKE deficit on the atmospheric side. Atmospheric and oceanic TKE dissipation rates converge to the expected law‐of‐the‐wall profiles away from the surface but clearly show the importance of waves in atmosphere‐ocean interaction closer to the sea surface. Deviations from the law‐of‐the‐wall are presented as signature of wave‐induced turbulence close to the ocean surface. Key Points: Turbulent Kinetic Energy (TKE) dissipation rates across the interface show a deficit and enhancement supported by the wave fieldA depth integrated subsurface TKE budget highlights the relevance of the transport terms and their connection to wave breakingThe atmospheric TKE dissipation rate deficit can be explained in terms of wave‐induced perturbations mediating energy input to the waves [ABSTRACT FROM AUTHOR]

Bubble plume penetration depths have been identified as a key parameter linking subsurface turbulent kinetic energy (TKE) dissipation rates and whitecaps. From data collected in the Atlantic sector of the Southern Ocean, nominally 50°S 40°W, bubble plume penetration depths were estimated from Acoustic Doppler Current Profiler measurements of the acoustic backscatter anomaly. Bubble presence at depth was corroborated using independent measurements of optical scattering. Here, an effective wavelength, observations of significant wave height and atmospheric forcing were used to scale penetration depths of breaking waves under open ocean conditions. The parameterization was developed assuming a correlation between the observed penetration depth and an estimate of the TKE dissipation rate enhancement under breaking waves. The effective wavelength was defined from the effective phase speed based on a momentum and energy balance across the atmospheric wave boundary layer and was considered to be the largest actively wind‐coupled wave and representative of large‐scale breaking for wave ages ranging from 15 to 35 (i.e., 15 ≤ 〈cp/u*〉 ≤ 35). This yields a dimensional penetration depth parameterization in terms of inverse wave age and the length scales under consideration. The parameterization captures the bubble plume penetration depth with stronger forcing leading to deeper injections, reaching up to 9 m. Both length scales are effective at defining the depth of a wave‐affected layer in terms of bubble presence with the effective wavelength better collapsing the data under mixed conditions with deeper plumes associated to larger fractional whitecap coverage. Plain Language Summary: The depth to which waves breaking at the ocean surface influence oceanic processes in the mixed layer, including the transfer of momentum, heat and gases between the atmosphere and ocean, is an ongoing and active area of research. Parameterizations and observations describing the vertical extent of wave‐driven effects, including whitecaps and vertical jets associated with Langmuir circulation, are relevant for numerical circulation models and our understanding of wave breaking and dissipation dynamics. Here, observations of atmospheric and oceanic conditions, principally wind, wave, and inferred bubble plume penetration depths collected in the Atlantic sector of the Southern Ocean were used to build a parameterization for estimating the vertical extent of bubble injections and for inferring the depth of the wave‐affected layer. These results suggest that wavelengths shorter than the dominant peak and significant wave heights properly weighted by atmospheric parameters are a good proxy for defining the extent of wave‐driven bubble transport. Key Points: The significant wave height and the effective wavelength were used to scale bubble penetration depths under open ocean conditionsBoth length scales successfully provide a penetration depth parameterization with the effective wavelength better collapsing the data [ABSTRACT FROM AUTHOR]

The current status of meteorological sensors used aboard ships and buoys to measure the air-sea fluxes of momentum, heat, and freshwater is reviewed. Methods of flux measurement by the bulk aerodynamic, inertial dissipation and eddy-correlation methods are considered; and areas are identified where improvements are needed in measurement of the basic variables. In some cases, what is required is the transition from emergent to operational technology, in others new technologies are needed. Uncertainties in measured winds caused by flow distortion over the ship are discussed; and the possible role of computational fluid mechanics models to obtain corrections is considered. Basic studies are also needed on the influence of waves and rain on the fluxes. The issues involved in the specification of sea surface temperature are described, and the relative merits of the available sensors are discussed. The improved capability of buoy-mounted systems will depend on the emergence of low-power instruments, and/or new means of increasing the available power capacity. Other issues covered include the continuing uncertainty about the performance of rain gauges and short-wave radiometers. Also, the requirements for new instruments to extend the range of observations to extreme wind conditions are outlined, and the latest developments in the measurement of aerosol fluxes by eddy-correlation are presented. [ABSTRACT FROM AUTHOR]

Previous investigations of the wind stress in the marine surface layer have primarily focused on determining the stress magnitude (momentum flux) and other scalar variables (e.g., friction velocity, drag coefficient, roughness length). However, the stress vector is often aligned with a direction different from that of the mean wind flow. In this paper, the focus is on the study of the stress vector direction relative to the mean wind and surface-wave directions. Results based on measurements made during three field campaigns onboard the R/P Floating Instrument Platform (FLIP) in the Pacific are discussed. In general, the wind stress is a vector sum of the 1) pure shear stress (turbulent and viscous) aligned with the mean wind shear, 2) wind-wave-induced stress aligned with the direction of the pure wind-sea waves, and 3) swell-induced stress aligned with the swell direction. The direction of the wind-wave-induced stress and the swell-induced stress components may coincide with, or be opposite to, the direction of wave propagation (pure wind waves and swell, respectively). As a result, the stress vector may deviate widely from the mean wind flow, including cases in which stress is directed across or even opposite to the wind. [ABSTRACT FROM AUTHOR]

This paper describes two methods for computing direct covariance fluxes from anemometers mounted on moving platforms at sea. These methods involve the use of either a strapped-down or gyro-stabilized system that are used to compute terms that correct for the 1) instantaneous tilt of the anemometer due to the pitch, roll, and heading variations of the platform; 2) angular velocities at the anemometer due to rotation of the platform about its local coordinate system axes; and 3) translational velocities of the platform with respect to a fixed frame of reference. The paper provides a comparison of fluxes computed with three strapped-down systems from two recent field experiments. These comparisons shows that the direct covariance fluxes are in good agreement with fluxes derived using the bulk aerodynamic method. Additional comparisons between the ship system and the research platform FLIP indicate that flow distortion systematically increases the momentum flux by 15%. Evidence suggests that this correction is appropriate for a commonly used class of research vessels. The application of corrections for both motion contamination and flow distortion results in direct covariance flux estimates with an uncertainty of approximately 10%--20%. [ABSTRACT FROM AUTHOR]