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Dataset: Snail larvae in turbulence and waves, Dispersing marine larvae can alter their physical transport by swimming vertically or sinking in response to environmental signals. However, it remains unknown whether any signals could enable larvae to navigate over large scales. We tested whether flow-induced larval behaviors vary with adults' physical environments using congeneric snail larvae from the wavy continental shelf (Tritia trivittata) and from turbulent inlets (Tritia obsoleta). This dataset includes observations of larvae in turbulence, in rotating flows dominated by vorticity or strain rates, and in rectilinear wave oscillations. Larval and water motion were observed using near-infrared particle image velocimetry (IR PIV), and analyses identified threshold signals causing larvae to change their direction or magnitude of propulsive force. The two species reacted similarly to turbulence but differently to waves, and their transport patterns would diverge in wavy, offshore regions. Wave-induced behaviors provide evidence that larvae may detect waves as both motions and sounds useful in navigation. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/739790, NSF Division of Ocean Sciences (NSF OCE) OCE-1060622

The effects of wind-driven whitecapping on the evolution of the ocean surface boundary layer are examined using an idealized one-dimensional Reynolds-averaged Navier–Stokes numerical model. Whitecapping is parameterized as a flux of turbulent kinetic energy through the sea surface and through an adjustment of the turbulent length scale. Simulations begin with a two-layer configuration and use a wind that ramps to a steady stress. This study finds that the boundary layer begins to thicken sooner in simulations with whitecapping than without because whitecapping introduces energy to the base of the boundary layer sooner than shear production does. Even in the presence of whitecapping, shear production becomes important for several hours, but then inertial oscillations cause shear production and whitecapping to alternate as the dominant energy sources for mixing. Details of these results are sensitive to initial and forcing conditions, particularly to the turbulent length scale imposed by breaking waves and the transfer velocity of energy from waves to turbulence. After 1–2 days of steady wind, the boundary layer in whitecapping simulations has thickened more than the boundary layer in simulations without whitecapping by about 10%–50%, depending on the forcing and initial conditions.

Author Posting. © American Meteorological Society, 2015. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 45 (2015): 2006–2024, doi:10.1175/JPO-D-14-0234.1., The effects of wind-driven whitecapping on the evolution of the ocean surface boundary layer are examined using an idealized one-dimensional Reynolds-averaged Navier–Stokes numerical model. Whitecapping is parameterized as a flux of turbulent kinetic energy through the sea surface and through an adjustment of the turbulent length scale. Simulations begin with a two-layer configuration and use a wind that ramps to a steady stress. This study finds that the boundary layer begins to thicken sooner in simulations with whitecapping than without because whitecapping introduces energy to the base of the boundary layer sooner than shear production does. Even in the presence of whitecapping, shear production becomes important for several hours, but then inertial oscillations cause shear production and whitecapping to alternate as the dominant energy sources for mixing. Details of these results are sensitive to initial and forcing conditions, particularly to the turbulent length scale imposed by breaking waves and the transfer velocity of energy from waves to turbulence. After 1–2 days of steady wind, the boundary layer in whitecapping simulations has thickened more than the boundary layer in simulations without whitecapping by about 10%–50%, depending on the forcing and initial conditions., We thank Skidmore College for financial and infrastructure support, and Skidmore and the National Science Foundation for funding travel to meetings where early versions of this work were presented. We also thank the National Science Foundation, Oregon State University, Jonathan Nash, and Joe Jurisa for funding and hosting a workshop on River Plume Mixing in October, 2013, where ideas and context for this paper were developed., 2016-02-01

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 10 (2013): 5517-5531, doi:10.5194/bg-10-5517-2013., Observational gaps limit our understanding of particle flux attenuation through the upper mesopelagic because available measurements (sediment traps and radiochemical tracers) have limited temporal resolution, are labor-intensive, and require ship support. Here, we conceptually evaluate an autonomous, optical proxy-based method for high-resolution observations of particle flux. We present four continuous records of particle flux collected with autonomous profiling floats in the western Sargasso Sea and the subtropical North Pacific, as well as one shorter record of depth-resolved particle flux near the Bermuda Atlantic Time-series Study (BATS) and Oceanic Flux Program (OFP) sites. These observations illustrate strong variability in particle flux over very short (~1-day) timescales, but at longer timescales they reflect patterns of variability previously recorded during sediment trap time series. While particle flux attenuation at BATS/OFP agreed with the canonical power-law model when observations were averaged over a month, flux attenuation was highly variable on timescales of 1–3 days. Particle fluxes at different depths were decoupled from one another and from particle concentrations and chlorophyll fluorescence in the immediately overlying surface water, consistent with horizontal advection of settling particles. We finally present an approach for calibrating this optical proxy in units of carbon flux, discuss in detail the related, inherent physical and optical assumptions, and look forward toward the requirements for the quantitative application of this method in highly time-resolved studies of particle export and flux attenuation., M.L.E. was supported by a WHOI Postdoctoral Scholar fellowship, and the floats used in this project were funded by the above NASA grant and by ONR (DURIP, N00014-10-1-0776).

Observations of turbulent kinetic energy (TKE) dynamics in the ocean surface boundary layer are presented here and compared with results from previous observational, numerical, and analytic studies. As in previous studies, the dissipation rate of TKE is found to be higher in the wavy ocean surface boundary layer than it would be in a flow past a rigid boundary with similar stress and buoyancy forcing. Estimates of the terms in the turbulent kinetic energy equation indicate that, unlike in a flow past a rigid boundary, the dissipation rates cannot be balanced by local production terms, suggesting that the transport of TKE is important in the ocean surface boundary layer. A simple analytic model containing parameterizations of production, dissipation, and transport reproduces key features of the vertical profile of TKE, including enhancement near the surface. The effective turbulent diffusion coefficient for heat is larger than would be expected in a rigid-boundary boundary layer. This diffusion coefficient is predicted reasonably well by a model that contains the effects of shear production, buoyancy forcing, and transport of TKE (thought to be related to wave breaking). Neglect of buoyancy forcing or wave breaking in the parameterization results in poor predictions of turbulent diffusivity. Langmuir turbulence was detected concurrently with a fraction of the turbulence quantities reported here, but these times did not stand out as having significant differences from observations when Langmuir turbulence was not detected.

Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 1077–1096, doi:10.1175/2008JPO4044.1., Observations of turbulent kinetic energy (TKE) dynamics in the ocean surface boundary layer are presented here and compared with results from previous observational, numerical, and analytic studies. As in previous studies, the dissipation rate of TKE is found to be higher in the wavy ocean surface boundary layer than it would be in a flow past a rigid boundary with similar stress and buoyancy forcing. Estimates of the terms in the turbulent kinetic energy equation indicate that, unlike in a flow past a rigid boundary, the dissipation rates cannot be balanced by local production terms, suggesting that the transport of TKE is important in the ocean surface boundary layer. A simple analytic model containing parameterizations of production, dissipation, and transport reproduces key features of the vertical profile of TKE, including enhancement near the surface. The effective turbulent diffusion coefficient for heat is larger than would be expected in a rigid-boundary boundary layer. This diffusion coefficient is predicted reasonably well by a model that contains the effects of shear production, buoyancy forcing, and transport of TKE (thought to be related to wave breaking). Neglect of buoyancy forcing or wave breaking in the parameterization results in poor predictions of turbulent diffusivity. Langmuir turbulence was detected concurrently with a fraction of the turbulence quantities reported here, but these times did not stand out as having significant differences from observations when Langmuir turbulence was not detected., The Office of Naval Research funded this work as a part of CBLAST-Low.

Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 88 (2007): 341-356, doi:10.1175/bams-88-3-341., The Office of Naval Research's Coupled Boundary Layers and Air–Sea Transfer (CBLAST) program is being conducted to investigate the processes that couple the marine boundary layers and govern the exchange of heat, mass, and momentum across the air–sea interface. CBLAST-LOW was designed to investigate these processes at the low-wind extreme where the processes are often driven or strongly modulated by buoyant forcing. The focus was on conditions ranging from negligible wind stress, where buoyant forcing dominates, up to wind speeds where wave breaking and Langmuir circulations play a significant role in the exchange processes. The field program provided observations from a suite of platforms deployed in the coastal ocean south of Martha's Vineyard. Highlights from the measurement campaigns include direct measurement of the momentum and heat fluxes on both sides of the air–sea interface using a specially constructed Air–Sea Interaction Tower (ASIT), and quantification of regional oceanic variability over scales of O (1–104 mm) using a mesoscale mooring array, aircraft-borne remote sensors, drifters, and ship surveys. To our knowledge, the former represents the first successful attempt to directly and simultaneously measure the heat and momentum exchange on both sides of the air–sea interface. The latter provided a 3D picture of the oceanic boundary layer during the month-long main experiment. These observations have been combined with numerical models and direct numerical and large-eddy simulations to investigate the processes that couple the atmosphere and ocean under these conditions. For example, the oceanic measurements have been used in the Regional Ocean Modeling System (ROMS) to investigate the 3D evolution of regional ocean thermal stratification. The ultimate goal of these investigations is to incorporate improved parameterizations of these processes in coupled models such as the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) to improve marine f, This work was supported by the Office of Naval Research.

Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Atmospheric and Oceanic Technology 27 (2010): 889-907, doi:10.1175/2009JTECHO682.1., Recently, the velocity observations of acoustic Doppler current profilers (ADCPs) have been successfully used to estimate turbulent Reynolds stresses in estuaries and tidal channels. However, the presence of surface gravity waves can significantly bias stress estimates, limiting application of the technique in the coastal ocean. This work describes a new approach to estimate Reynolds stresses from ADCP velocities obtained in the presence of waves. The method fits an established semiempirical model of boundary layer turbulence to the measured turbulent cospectra at frequencies below those of surface gravity waves to estimate the stress. Applied to ADCP observations made in weakly stratified waters and variable significant wave heights, estimated near-bottom and near-surface stresses using this method compared well with independent estimates of the boundary stresses in contrast to previous methods. Additionally, the vertical structure of tidal stress estimated using the new approach matched that inferred from a linear momentum balance at stress levels below the estimated stress uncertainties. Because the method makes an estimate of the horizontal turbulent length scales present as part of the model fit, these results can also enable a direct correction for the mean bias errors resulting from instrument tilt, if these scales are long relative to the beam separation., AK acknowledges support from the WHOI Coastal Ocean Institute, and SL acknowledges support from NSF Ocean Science Grant OCE-0548961.

This study presents observations of turbulence dynamics made during the low winds portion of the Coupled Boundary Layers and Air-Sea Transfer experiment (CBLAST-low) in the ocean surface boundary layer. Observations include turbulent fluxes, turbulent kinetic energy, and the length scales of flux-carrying and energy-containing eddies. The observations of turbulent fluxes allowed the closing of heat and momentum budgets across the air-sea interface. The flux-carrying eddies are similar in size to those expected in rigid-boundary turbulence, but energy-containing eddies are smaller than those in rigid boundary turbulence. The observations confirm previous speculation that surface wave breaking provides a surface source of turbulent kinetic energy that dissipates as it is transported to depth. A model that includes the effects of shear production, transport, and dissipation is able to reproduce the enhancement of turbulent kinetic energy near the ocean surface. The ocean surface boundary layer is observed to have small but finite temperature gradients that are related to the boundary fluxes of heat and momentum, as assumed by closure models. However, the turbulent diffusivity of heat in the surface boundary layer is larger than predicted by rigid-boundary closure models. This discrepancy can be explained by the addition of wave breaking to the rigid-boundary model., Additional contract numbers: N00014-03-1-0681 and NAG5-11933. Sponsored in part by National Aeronautics and Space Administration.

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2008, This study presents observations of turbulence dynamics made during the low winds portion of the Coupled Boundary Layers and Air-Sea Transfer experiment (CBLAST-Low). Observations were made of turbulent fluxes, turbulent kinetic energy, and the length scales of flux-carrying and energy-containing eddies in the ocean surface boundary layer. A new technique was developed to separate wave and turbulent motions spectrally, using ideas for turbulence spectra that were developed in the study of the bottom boundary layer of the atmosphere. The observations of turbulent fluxes allowed the closing of heat and momentum budgets across the air-sea interface. The observations also show that flux-carrying eddies are similar in size to those expected in rigid-boundary turbulence, but that energy-containing eddies are smaller than those in rigid-boundary turbulence. This suggests that the relationship between turbulent kinetic energy, depth, and turbulent diffusivity are different in the ocean surface boundary layer than in rigid-boundary turbulence. The observations confirm previous speculation that surface wave breaking provides a surface source of turbulent kinetic energy that is transported to depth where it dissipates. A model that includes the effects of shear production, wave breaking and dissipation is able to reproduce the enhancement of turbulent kinetic energy near the wavy ocean surface. However, because of the different length scale relations in the ocean surface boundary layer, the empirical constants in the energy model are different from the values that are used to model rigid-boundary turbulence. The ocean surface boundary layer is observed to have small but finite temperature gradients that are related to the boundary fluxes of heat and momentum, as assumed by closure models. However, the turbulent diffusivity of heat in the surface boundary layer is larger than predicted by rigid-boundary closure models. Including the combined effects of wave breaking, stress, an, This work was supported by Office of Naval Research grants N00014-00-1-0409, N00014-01-1-0029, and N00014-03-1-0681, the Woods Hole Oceanographic Institution Academic Programs Office, and National Aeronautics and Space Administration grant NAG5-11933.