A5108545805- Oceanographic and Atmospheric Processes
- Ocean Waves and Remote Sensing
- Coastal and Marine Dynamics
- Tropical and Extratropical Cyclones Research
- Underwater Acoustics Research
- Meteorological Phenomena and Simulations
- Geological formations and processes
- Aeolian processes and effects
- Coastal wetland ecosystem dynamics
- Experimental and Theoretical Physics Studies
- Magnetic Properties and Applications
- Solar and Space Plasma Dynamics
- Atmospheric and Environmental Gas Dynamics
- Fluid Dynamics and Turbulent Flows
- Climate variability and models
- High voltage insulation and dielectric phenomena
- Plasma Diagnostics and Applications
- Hydrology and Sediment Transport Processes
- Electrohydrodynamics and Fluid Dynamics
- Seismic Waves and Analysis
- Marine and fisheries research
- Methane Hydrates and Related Phenomena
- Soil erosion and sediment transport
- Power Transformer Diagnostics and Insulation
- Various Chemistry Research Topics
Woodwell Climate Research Center
2025
Woods Hole Oceanographic Institution
2010-2024
University of Colorado Boulder
2000
Northwest Research Associates
1994
University of Delaware
1985-1987
Harvard University
1897-1909
Harvard University Press
1879-1897
Thomas Jefferson National Accelerator Facility
1894
MIT Lincoln Laboratory
1891-1892
University of California, San Diego
1887
Accuracy of the acoustic Doppler velocimeter (ADV) is evaluated in this paper. Simultaneous measurements open-channel flow were undertaken a 17-m flume using an ADV and laser velocimeter. Flow velocity records obtained by both instruments are used for estimating true (“ground truth”) characteristics noise variances encountered during experimental runs. The measured values compared with estimates variance (〈u′2〉, 〈w′2〉) covariance (〈u′w′〉) predicted semiempirical models flow. analysis showed...
Measurements of velocity, density, and pressure gradient in the lower Hudson River estuary were used to quantify dominant terms momentum equation characterize their variations at tidal spring–neap timescales. The vertical flux (assumed be due mainly turbulent shear stress) was estimated indirectly, based on residual from acceleration terms. indirect estimates stress compared favorably bottom using a quadratic drag law, supporting hypothesis that involves local balance between acceleration,...
The Office of Naval Research's Coupled Boundary Layers and Air–Sea Transfer (CBLAST) program is being conducted to investigate the processes that couple marine boundary layers govern exchange heat, mass, momentum across air–sea interface. CBLAST-LOW was designed these at low-wind extreme where are often driven or strongly modulated by buoyant forcing. focus on conditions ranging from negligible wind stress, forcing dominates, up speeds wave breaking Langmuir circulations play a significant...
The Ocean Observatories Initiative (OOI) is an integrated network that enables scientific investigation of interlinked physical, chemical, biological and geological processes throughout the global ocean. With near real-time data delivery via a common Cyberinfrastructure, OOI instruments two contrasting ocean systems at three scales. Regional Cabled Array tectonic plate overlying in northeast Pacific, providing permanent electro-optical cable connecting multiple seafloor nodes provide high...
Surface waves can produce large biases in estimates of turbulent shear stress obtained from single-sensor measurements velocity if there is even a small uncertainty the orientation either sensor or principal axes wave-induced field. The bias be diminished substantially by differencing two sensors separated distance larger than correlation scale turbulence but comparison to inverse wavenumber surface waves. If separation sufficiently large, then minus density times half covariance between...
Moored temperature and shipboard CTD observations from a northern California coastal upwelling region reveal variable bottom mixed-layer heights that are typically 5–15 m, but occasionally exceed 50 m. Observations Oregon, California, Peru, indicate in regions, maximum tend to increase with water depth over the shelf, rarely half depth. Over shelf height is shown depend on stratification, current magnitude, direction. The dependence direction tends dominate response, thicker mixed layers...
Oscillatory turbulent flow produced near a rough seabed by linear surface waves is analyzed. An analogy to the wall region of steady shown be valid very bed and provides basis for model in which eddy viscosity product vertical length scale first two Fourier components shear velocity based on instantaneous, local stress. With this time‐varying model, an approximate closed‐form solution boundary layer obtained. Comparison with available laboratory measurements indicates that does fact vary...
The effects of stratification, planetary rotation and a sloping bottom combine to produce an asymmetric response in which the characteristics oceanic boundary layer depend on direction, addition magnitude, along-isobath velocity inviscid interior. is examined theoretically under idealized conditions motion begins from rest, flow uniform cross-isobath directions, water column initially uniformly stratified. analysis based integrated model, stress determined quadratic drag law, height...
Thick layers of fluid mud occur in strong tidal flows over the inner portion Amazon continental shelf regions salinity fronts associated with plume discharged from River. Detailed shipboard profile measurements obtained this region during A Multidisciplinary Shelf Sediment Study (AMASSEDS) provide an unprecedented opportunity to examine structure and dynamics muds under natural conditions. The analysis focuses on which motion is fully turbulent suspended sediment dominates stratification....
The solution for the turbulent near‐bottom boundary layer produced by a progressive wave train is advanced to second order in steepness. As first‐order analysis (part 1) effective viscosity assumed be product of vertical length scale and first few Fourier components shear velocity based on instantaneous, local bed stress. An analytical second‐order flow field obtained, with attention directed primarily toward second‐order, wave‐induced steady current or mass transport. transport found depend...
Velocities produced by energetic waves can contaminate direct covariance estimates of near-bottom turbulent shear stress and heat flux. A new adaptive filtering technique is introduced to minimize the contribution wave-induced motions measured covariances. The requires use two sensors separated in space assumes that spatial coherence scale much longer than turbulence. proposed applied an extensive set data collected bottom boundary layer New England shelf. Results from oceanic test...
Velocity measurements within 1 m of the bottom in approximately 4.5-m water depth on a sand beach provide estimates turbulent Reynolds shear stress, using dual-sensor technique that removes contamination by surface waves, and inertial-range dissipation. When combined with wave along cross-shore transect nearby wind measurements, dataset provides direct terms simplified equations for alongshore momentum turbulence energetics permits examination semiempirical relationships between stress...
Shear instability is the dominant mechanism for converting fluid motion to mixing in stratified ocean and atmosphere. The transition turbulence has been well characterized laboratory settings numerical simulations at moderate Reynolds number—it involves “rolling up”, i.e., overturning of density structure within cores instabilities. In contrast, measurements an energetic estuarine shear zone reveal that induced by high number does not primarily occur cores; rather it results from secondary...
Abstract Observations of turbulent kinetic energy (TKE) dynamics in the ocean surface boundary layer are presented here and compared with results from previous observational, numerical, analytic studies. As studies, dissipation rate TKE is found to be higher wavy than it would a flow past rigid similar stress buoyancy forcing. Estimates terms equation indicate that, unlike boundary, rates cannot balanced by local production terms, suggesting that transport important layer. A simple model...
Representing upper ocean turbulence accurately in models remains a great challenge for improving weather and climate projections. Langmuir circulation (LC) is turbulent process driven by wind surface waves that plays key role transferring momentum, heat, mass the oceanic layer. We present direct comparison between observations large eddy simulations, based on wave‐averaged Navier‐Stokes equation, of an LC growth event. The evolution cross‐wind velocity variance spatial scales, as well mixed...
A set of moored, bottom-mounted and shipboard measurements, obtained in a straight section the lower Hudson estuary during late summer early fall 1995, determine velocity, density, along-channel pressure gradient throughout 15-m water column, as well providing direct eddy-correlation estimates Reynolds stress indirect inertial-range dissipation within 3 m bottom. The analysis focuses on testing 1) simplified turbulent kinetic energy equation, which production balances dissipation; 2)...
Simultaneous in situ observations of floc size, waves, and currents a continental shelf bottom boundary layer do not support generally accepted functional relationships between turbulence size the sea. In September October 1996 January 1997, two tripods were deployed 70 m water on south Woods Hole, Massachusetts. On one camera photographed particles suspension 1.2 above that had equivalent circular diameters larger than 250 μm, other, three horizontally displaced acoustic current meters...
A remarkable set of shore‐oblique sand ridges occupies the inner portion storm‐dominated Middle Atlantic and South Bights, off east coast United States America. mechanism for present‐day formation growth these distinctive geological features follows from a linearized analysis stability alongshore‐periodic topographical perturbations, based on depth‐averaged fluid dynamical model with simple representation sediment transport. The indicates exponential as result offshore deflection...
Abstract The effect of breaking-wave-generated turbulence on the mean circulation, turbulence, and bottom stress in surf zone is poorly understood. A one-dimensional vertical coupled (k–ɛ) mean-flow model developed that incorporates wave breaking with a time-dependent surface flux uses existing (published) closures. No parameters are tuned to optimize model–data agreement. qualitatively reproduces dissipation production during most energetic breaking-wave conditions 4.5-m water depth off...
Abstract The vertical structure of the dissipation turbulence kinetic energy was observed in nearshore region (3.2-m mean water depth) with a tripod three acoustic Doppler current meters off sandy ocean beach. Surface and bottom boundary layer scaling concepts overlap this region. No depth-limited wave breaking occurred at tripod, but wind-induced whitecapping did occur. Dissipation is maximum near surface minimum middepth, secondary bed. does not follow surfzone scaling, nor it “log layer”...
Abstract Langmuir circulation (LC) is a turbulent upper-ocean process driven by wind and surface waves that contributes significantly to the transport of momentum, heat, mass in oceanic layer. The authors have previously performed direct comparison large-eddy simulations observations response event with rapid mixed layer deepening. evolution simulated crosswind velocity variance spatial scales, as well deepening, was only consistent if LC effects are included model. Based on an analysis...
Abstract Climate change redistributes turbulence in both space and time, adding urgency to understanding of effects. Many analytic analog models used simulate assess effects on plankton rely simple Couette flow. There shear rates are constant spatially uniform, hence so is vorticity. Over the last decade, however, research within fluid dynamics has focused structure dissipative vortices time. Vorticity gradients, finite net diffusion vorticity small radii curvature streamlines ubiquitous...
Abstract Measurements in the South China Sea reveal structure of bottom boundary layer beneath onshore propagating highly nonlinear internal solitary waves depression. Offshore directed free stream velocities 13 with durations 10–20 min and up to 1.4 m/s are consistent wave solution Korteweg‐de Vries equation as phase estimated from pressures velocities. The measurements indicate a thin during acceleration, thicker an inflected velocity deceleration, long‐lived sediment laden wake, after...