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1. Observations of Breaking Wave Dissipation and Their Relationship to Atmosphere‐Ocean Energy Transfer

   https://doi.org/10.1029/2024JC022130  

   Hogan, L.; Zappa, C_J; Cifuentes‐Lorenzen, A.; Edson, J_B; O’Donnell, J.; Ullman, D_S (June 2025, Journal of Geophysical Research: Oceans)

   Abstract Energy is transferred from the atmosphere to the ocean primarily through ocean surface waves, and the majority is dissipated locally in the near‐surface ocean. Observations of turbulent kinetic energy (TKE) in the upper ocean have shown dissipation rates exceeding law‐of‐the‐wall theory by an order of magnitude. The excess near‐surface ocean TKE dissipation rate is thought to be driven primarily by wave breaking, which limits wave growth and transfers energy from the surface wave field to the wave‐affected layer of the ocean. Here, the statistical properties of breaking wave dynamics in a coastal area are extracted from visible imagery and used to estimate TKE dissipation rates due to breaking waves. The statistical properties of whitecap dynamics are quantified with Λ(c), a distribution of total whitecap crest length per unit area as a function of crest speed, and used to compute energy dissipation by breaking waves, S_ds. S_dsapproximately balances elevated subsurface dissipation in young seas but accounts for only a fraction of subsurface dissipation in older seas. The wind energy input is estimated from wave spectra from polarimetric imagery and laser altimetry. S_dsbalances the wind energy input except under high winds. Λ(c)‐derived estimates of TKE dissipation rates by breaking waves compare well with the atmospheric deficit in TKE dissipation, a measure of energy input to the wave field (Cifuentes‐Lorenzen et al., 2024). These results tie the observed atmospheric dissipation deficit and enhancement in subsurface TKE dissipation to wave driven energy transport, constraining the TKE dissipation budget near the air‐sea interface. 

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2. Improving Wave‐Based Air‐Sea Momentum Flux Parameterization in Mixed Seas

   https://doi.org/10.1029/2022JC019277  

   Sauvage, C; Seo, H; Clayson, CA; Edson, JB (March 2023, Journal of Geophysical Research: Oceans)

   In winter, the Northwest Tropical Atlantic Ocean can be characterized by various wave age-based interactions among ocean current, surface wind and surface waves, which are critical for accurately describing surface wind stress. In this work, coupled wave-ocean-atmosphere model simulations are conducted using two different wave roughness parameterizations within COARE3.5, including one that relies solely on wind speed and another that uses wave age and wave slope as inputs. Comparisons with the directly measured momentum fluxes during the ATOMIC/EUREC4A experiments in winter 2020 show that, for sea states dominated by short wind waves under moderate to strong winds, the wave-based formulation (WBF) increases the surface roughness length in average by 25% compared to the wind-speed-based approach. For sea states dominated by remotely generated swells under moderate to strong wind intensity, the WBF predicts significantly lower roughness length and surface stress (≈15%), resulting in increased near-surface wind speed above the constant flux layer (≈5%). Further investigation of the mixed sea states in the model and data indicates that the impact of swell on wind stress is over-emphasized in the COARE3.5 WBF, especially under moderate wind regimes. Various approaches are explored to alleviate this deficiency by either introducing directional alignment between wind and waves or using the mean wave period instead of the wave period corresponding to the spectral peak to compute the wave age. The findings of this study are likely to be site-dependent, and mostly concern specific regimes of wind and waves where the original parameterization was deficient. 

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3. Identifying Ocean Swell Generation Events from Ross Ice Shelf Seismic Data

   https://doi.org/10.1175/JTECH-D-19-0093.1  

   Hell, Momme C.; Cornelle, Bruce D.; Gille, Sarah T.; Miller, Arthur J.; Bromirski, Peter D. (November 2019, Journal of Atmospheric and Oceanic Technology)

   Abstract Strong surface winds under extratropical cyclones exert intense surface stresses on the ocean that lead to upper-ocean mixing, intensified heat fluxes, and the generation of waves, that, over time, lead to swell waves (longer than 10-s period) that travel long distances. Because low-frequency swell propagates faster than high-frequency swell, the frequency dependence of swell arrival times at a measurement site can be used to infer the distance and time that the wave has traveled from its generation site. This study presents a methodology that employs spectrograms of ocean swell from point observations on the Ross Ice Shelf (RIS) to verify the position of high wind speed areas over the Southern Ocean, and therefore of extratropical cyclones. The focus here is on the implementation and robustness of the methodology in order to lay the groundwork for future broad application to verify Southern Ocean storm positions from atmospheric reanalysis data. The method developed here combines linear swell dispersion with a parametric wave model to construct a time- and frequency-dependent model of the dispersed swell arrivals in spectrograms of seismic observations on the RIS. A two-step optimization procedure (deep learning) of gradient descent and Monte Carlo sampling allows detailed estimates of the parameter distributions, with robust estimates of swell origins. Median uncertainties of swell source locations are 110 km in radial distance and 2 h in time. The uncertainties are derived from RIS observations and the model, rather than an assumed distribution. This method is an example of supervised machine learning informed by physical first principles in order to facilitate parameter interpretation in the physical domain. 

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4. Wind Fetch and Direction Effects on Langmuir Turbulence in a Coastal Ocean

   https://doi.org/10.1029/2021JC018222  

   Wang, Xingchi; Kukulka, Tobias; Plueddemann, Albert J. (April 2022, Journal of Geophysical Research: Oceans)

   Abstract Mixing processes in the upper ocean play a key role in transferring heat, momentum, and matter in the ocean. These mixing processes are significantly enhanced by wave‐driven Langmuir turbulence (LT). Based on a paired analysis of observations and simulations, this study investigates wind fetch and direction effects on LT at a coastal site south of the island Martha’s Vineyard (MA, USA). Our results demonstrate that LT is strongly influenced by wind fetch and direction in coastal oceans, both of which contribute to controlling turbulent coastal transport processes. For northerly offshore winds, land limits the wind fetch and wave development, whereas southerly winds are associated with practically infinite fetch. Observed and simulated two‐dimensional wave height spectra reveal persistent southerly swell and substantially more developed wind‐driven waves from the south. For oblique offshore winds, waves develop more strongly in the alongshore direction with less limited fetch, resulting in significant wind and wave misalignments. Observations of coherent near‐surface crosswind velocities indicate that LT is only present for sufficiently developed waves. The fetch‐limited northerly winds inhibit wave developments and the formation of LT. In addition to limited fetch, strong wind–wave misalignments prevent LT development. Although energetic and persistent, swell waves do not substantially influence LT activity during the observation period because these relatively long swell waves are associated with small Stokes drift shear. These observational results agree well with turbulence‐resolving large eddy simulations (LESs) based on the wave‐averaged Navier–Stokes equation, validating the LES approach to coastal LT in the complex wind and wave conditions. 

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5. Accounting for Ocean Waves and Current Shear in Wind Stress Parameterization

   https://doi.org/10.1007/s10546-025-00926-9  

   Ortiz-Suslow, David_G; Laxague, Nathan; Björkqvist, Jan-Victor; Curcic, Milan (August 2025, Boundary-Layer Meteorology)

   Abstract The wind shear stress at the ocean surface drives momentum exchange across the air-sea interface regulating atmospheric and oceanic phenomena. Theoretically, the mean wind stress acts in a reference frame moving with the ocean surface; however, the relative motion between the air and ocean surface layers is conventionally neglected in bulk transfer formulae. Recent developments improving air-sea momentum flux quantification advocate for explicitly defining the air-sea relative wind, especially in the regime of low wind forcing, where surface currents may approach a significant fraction of the total wind speed. Yet, in practice, this new approach is typically applied using opportunistic definitions of the near-surface current. Here, we build on this recent work and propose a general framework for the bulk air-sea momentum flux that directly accounts for vertical current shear and surface waves in quantifying the stress at the interface. Our approach partitions the stress at the interface into viscous skin and (wave) form drag components, each applied to their relevant surface advections, which are quantified using the inertial motions within the sub-surface log layer and the modulation of waves by currents predicted by linear theory, respectively. The efficacy of this approach is demonstrated using an extensive oceanic dataset from the Coastal Endurance Array (Ocean Observatories Initiative) offshore of Newport, Oregon (2017–2023) that includes co-located measurements of direct covariance wind stress, directional wave spectra, and current profiles. As expected, our framework does not alter the overall dependence of momentum flux on mean wind forcing, and we found the largest impacts at relatively low wind speeds. Below 3 m s$$^{-1}$$, accounting for sub-surface shear reduced form drag variation by 40–50% as compared to a current-agnostic approach; as compared to a shear-free current, i.e., slab ocean, a 35% reduction in form drag variation was found. At this wind forcing, neglecting the currents led to systematically overestimating the form stress by 20 to 50%—an effect that could not be captured by using the slab ocean approach. This framework builds on the existing understanding of wind-wave-current interaction, yielding a novel formulation that explicitly accounts for the role of current shear and surface waves in air-sea momentum flux. This work holds significant implications for air-sea coupled modeling in general conditions. 

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