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  • 1
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    Wave breaking turbulence at the offshore front of the Columbia River Plume (2015)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Geophysical Research Letters 41 (2014): 8987–8993, doi:10.1002/2014GL062274.
    Description: Observations at the Columbia River plume show that wave breaking is an important source of turbulence at the offshore front, which may contribute to plume mixing. The lateral gradient of current associated with the plume front is sufficient to block (and break) shorter waves. The intense whitecapping that then occurs at the front is a significant source of turbulence, which diffuses downward from the surface according to a scaling determined by the wave height and the gradient of wave energy flux. This process is distinct from the shear-driven mixing that occurs at the interface of river water and ocean water. Observations with and without short waves are examined, especially in two cases in which the background conditions (i.e., tidal flows and river discharge) are otherwise identical.
    Description: This work was supported by the Office of Naval Research, as part of the Data Assimilation and Remote Sensing for Littoral Applications (DARLA) project and in coordination with the Rivers and Inlets (RIVET) program.
    Keywords: Wave breaking ; Turbulence ; Mixing ; Wave-current interaction ; River plume
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
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    Hydraulics and mixing in a laterally divergent channel of a highly stratified estuary (2017)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 4743–4760, doi:10.1002/2016JC012455.
    Description: Estuarine mixing is often intensified in regions where topographic forcing leads to hydraulic transitions. Observations in the salt-wedge estuary of the Connecticut River indicate that intense mixing occurs during the ebb tide in regions of supercritical flow that is accelerated by lateral expansion of the channel. The zones of mixing are readily identifiable based on echo-sounding images of large-amplitude shear instabilities. The gradient Richardson number (Ri) averaged across the mixing layer decreases to a value very close to 0.25 during most of the active mixing phase. The along-estuary variation in internal Froude number and interface elevation are roughly consistent with a steady, inviscid, two-layer hydraulic representation, and the fit is improved when a parameterization for interfacial stress is included. The analysis indicates that the mixing results from lateral straining of the shear layer, and that the rapid development of instabilities maintains the overall flow near the mixing threshold value of Ri = 0.25, even with continuous, active mixing. The entrainment coefficient can be estimated from salt conservation within the interfacial layer, based on the finding that the mixing maintains Ri = 0.25. This approach leads to a scaling estimate for the interfacial mixing coefficient based on the lateral spreading rate and the aspect ratio of the flow, yielding estimates of turbulent dissipation within the pycnocline that are consistent with estimates based on turbulence-resolving measurements.
    Description: NSF Grant Number: OCE 0926427; Devonshire Scholars program
    Description: 2017-12-12
    Keywords: Internal hydraulics ; Mixing ; Gradient Richardson number ; Estuary
    Repository Name: Woods Hole Open Access Server
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  • 3
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    Stress, salt flux, and dynamics of a partially mixed estuary (2005)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-25
    Description: A field study was performed in the lower Hudson River, a partially mixed estuary with a relatively simple geometry (Figure 1), between August and October of 1995. The objectives of the study were (1) to quantify and characterize the turbulent transport of momentum and salt, and (2) to relate the turbulent transport processes to the local and estuary-wide dynamics. The measurement program consisted of fixed and shipboard components. At a central site, a moored array of temperature-conductivity sensors and optical backscatter sensors (OBS), a bottom-mounted acoustic Doppler current profiler (ADCP), and a bottom-mounted array of acoustic travel-time current sensors (BASS), temperature-conductivity sensors, and OBS sensors resolved the vertical structure of velocity, salinity and turbidity and the near-bottom turbulence structure. Moored and bottom-mounted velocity, temperature, conductivity and pressure sensors at five secondary sites quantified the spatial and temporal variabilty of velocity, salinity and bottom pressure. Shipboard measurements with an ADCP and a conductivity-temperature-depth (CTD) profiler, accompanied by an OBS sensor, resolved the spatial structure and tidal variability of velocity, salinity and turbidity along several cross-channel and along-channel transects. This report describes the measurements in detail. Section II describes the instrumentation, Section III describes the deployment and sampling schemes, Section IV describes the data processing, and Section V is a summary of plots of selected data. Section VI documents the data files and Sections VII and VII give acknowledgments and references.
    Description: Funding was provided by the National Science Foundation under Grant OCE-94-15617 and The Hudson River Foundation.
    Keywords: Stress ; Salt flux ; Mixed estuary
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 4
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    Turbulent and numerical mixing in a salt wedge estuary : dependence on grid resolution, bottom roughness, and turbulence closure (2017)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 692–712, doi:10.1002/2016JC011738.
    Description: The Connecticut River is a tidal salt wedge estuary, where advection of sharp salinity gradients through channel constrictions and over steeply sloping bathymetry leads to spatially heterogeneous stratification and mixing. A 3-D unstructured grid finite-volume hydrodynamic model (FVCOM) was evaluated against shipboard and moored observations, and mixing by both the turbulent closure and numerical diffusion were calculated. Excessive numerical mixing in regions with strong velocities, sharp salinity gradients, and steep bathymetry reduced model skill for salinity. Model calibration was improved by optimizing both the bottom roughness (z0), based on comparison with the barotropic tidal propagation, and the mixing threshold in the turbulence closure (steady state Richardson number, Rist), based on comparison with salinity. Whereas a large body of evidence supports a value of Rist ∼ 0.25, model skill for salinity improved with Rist ∼ 0.1. With Rist = 0.25, numerical mixing contributed about 1/2 the total mixing, while with Rist = 0.10 it accounted for ∼2/3, but salinity structure was more accurately reproduced. The combined contributions of numerical and turbulent mixing were quantitatively consistent with high-resolution measurements of turbulent mixing. A coarser grid had increased numerical mixing, requiring further reductions in turbulent mixing and greater bed friction to optimize skill. The optimal Rist for the fine grid case was closer to 0.25 than for the coarse grid, suggesting that additional grid refinement might correspond with Rist approaching the theoretical limit. Numerical mixing is rarely assessed in realistic models, but comparisons with high-resolution observations in this study suggest it is an important factor.
    Description: NSF Grant Number: OCE 0926427; ONR Grant Number: N00014-08-1-1115
    Description: 2017-07-28
    Keywords: Estuary ; Salt wedge ; Numerical mixing ; Turbulence closure ; Numerical model
    Repository Name: Woods Hole Open Access Server
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  • 5
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    Hydrodynamic baseline measurements in New Bedford Harbor (2006)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-05-26
    Description: Thls report includes a compilation of hydrodynamic data obtained in New Bedford Harbor, Massachusetts (Figue 1-1), for the purpose of providing baseline information for the selection of an outfall site for a seondary sewage treatment plant for the city of New Bedford. The observations were conducted by scientists at Woods Hole Oceanographic Institution, commencing in August, 1987 and continuing though March, 1988. They included moored and shipboard measurements of fluid velocity, temperature, salinity, dissolved oxygen and turbidity. The measurement program was designated as the "New Bedford Circulation Study", or NBCS. The study indicates that there are a variety of mechanisms responsible for the transport and exchange of water-masses, of which tidal currents are the most energetic, but wind-driven flows are likely the most effective at renewing the water within the Harbor. Estimates of residence times indicate minimum residence times of less than 2 days during periods of strong winds, and maximum residence times of 4 days or more in periods of weak to moderate south winds. Vertical stratificaton is weak in the winter and moderate in the summer, and it has a notable influence on vertical mixing and on the magnitude of shear currents.
    Description: Funding was provided by Camp, Dresser and McKee, Inc. under agreement effective 24 August 1987.
    Keywords: New Bedford Harbor ; Hydrodynamics ; Physical Oceanography
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 6
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    Sediment transport due to extreme events : the Hudson River estuary after tropical storms Irene and Lee (2014)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 40 (2013): 5451–5455, doi:10.1002/2013GL057906.
    Description: Tropical Storms Irene and Lee in 2011 produced intense precipitation and flooding in the U.S. Northeast, including the Hudson River watershed. Sediment input to the Hudson River was approximately 2.7 megaton, about 5 times the long-term annual average. Rather than the common assumption that sediment is predominantly trapped in the estuary, observations and model results indicate that approximately two thirds of the new sediment remained trapped in the tidal freshwater river more than 1 month after the storms and only about one fifth of the new sediment reached the saline estuary. High sediment concentrations were observed in the estuary, but the model results suggest that this was predominantly due to remobilization of bed sediment. Spatially localized deposits of new and remobilized sediment were consistent with longer term depositional records. The results indicate that tidal rivers can intercept (at least temporarily) delivery of terrigenous sediment to the marine environment during major flow events.
    Description: This research was supported by grants from the Hudson Research Foundation (002/07A) and the National Science Foundation (1232928).
    Description: 2014-04-18
    Keywords: Sediment transport ; Tidal river ; Estuary ; Sediment trapping
    Repository Name: Woods Hole Open Access Server
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  • 7
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    The role of morphology and wave-current interaction at tidal inlets : an idealized modeling analysis (2015)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 8818–8837, doi:10.1002/2014JC010191.
    Description: The outflowing currents from tidal inlets are influenced both by the morphology of the ebb-tide shoal and interaction with incident surface gravity waves. Likewise, the propagation and breaking of incident waves are affected by the morphology and the strength and structure of the outflowing current. The 3-D Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system is applied to numerically analyze the interaction between currents, waves, and bathymetry in idealized inlet configurations. The bathymetry is found to be a dominant controlling variable. In the absence of an ebb shoal and with weak wave forcing, a narrow outflow jet extends seaward with little lateral spreading. The presence of an ebb-tide shoal produces significant pressure gradients in the region of the outflow, resulting in enhanced lateral spreading of the jet. Incident waves cause lateral spreading and limit the seaward extent of the jet, due both to conversion of wave momentum flux and enhanced bottom friction. The interaction between the vorticity of the outflow jet and the wave stokes drift is also an important driving force for the lateral spreading of the plume. For weak outflows, the outflow jet is actually enhanced by strong waves when there is a channel across the bar, due to the “return current” effect. For both strong and weak outflows, waves increase the alongshore transport in both directions from the inlet due to the wave-induced setup over the ebb shoal. Wave breaking is more influenced by the topography of the ebb shoal than by wave-current interaction, although strong outflows show intensified breaking at the head of the main channel.
    Description: We are grateful to the Career Training Interexchange program that facilitated the training period of Maitane Olabarrieta within the USGS. Maitane Olabarrieta also acknowledges funding from the “Cantabria Campus International Augusto Gonzalez Linares Program.”WRG was supported by ONR grant N00014-13-1–0368.
    Description: 2015-06-23
    Keywords: Wave-current interaction ; Tidal inlets ; Nearshore ; Hydrodynamics ; Plane jet ; Vortex force method ; Rip current ; COAWST modeling system
    Repository Name: Woods Hole Open Access Server
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  • 8
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    The 17-meter flume at the Coastal Research Laboratory. Part II, Flow characteristics : technical report (2014)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-05-26
    Description: This report summarizes the characteristics of the idealized one-dimensional turbulent channel flow for which the 17-Meter Flume was designed, and describes a measurement program designed to determine whether the flume can in fact produce such a flow. The measured quantities include mean velocities, Reynolds stresses, turbulence intensities and velocity spectra. Measured profiles of mean velocity, Reynolds stress and turbulence intensity are consistent with previous theoretical and empirical results. Measured spectra, although consistent with expectations over a wide range of frequencies, indicate a few unexpected features, including a constant spectral density at high frequencies (possibly due to aliasing or high-frequency noise) , motion at a few well-defined high frequencies of order 10 hz (possibly due to structual vibrations), oscillations with time scales of order 30 s (possibly due to low-mode standing surface waves) and irregular motions with time scales of several minutes (possibly due to fluctuations in pump performance) . The unexpected features indicated by the spectra at high and low frequencies do not have a significant effect on mean velocities and low-order statistics, but they may be important in some applications.
    Description: Funding was provided by the Minerals Management Service under contract Number 14-12-0001-30262; Sea Grant under contract Number NA86AA-D-FG090; and the Office of Naval Research Young Investigator Program under contract Number N00014-86-K-0579.
    Keywords: Hydraulic models ; Turbulence
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 9
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    Southern Cape Cod Bay hypoxia data (2022)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-06-14
    Description: This project investigated the distribution of low dissolved oxygen bottom waters (hypoxia) in southern Cape Cod Bay. Hypoxia was documented for the first time in late summer 2019 and 2020 despite extensive monitoring for the past decade. The data include: 1) measurements of bottom dissolved oxygen collected in 2019 by the Massachusetts Division of Marine Fisheries (MDMF) and the Center for Coastal Studies (CCS) ; 2) full water column profiles of temperature, salinity, chlorophyll fluorescence, dissolved oxygen concentration and optical backscatter collected in late summer 2020 by the Woods Hole Oceanographic Institution (WHOI); 3) monthly water quality data including CTD with dissolved oxygen and chlorophyll fluorescence and discrete bottom samples analyzed for dissolved nutrients collected by the CCS for the period 2011-2020; 4) inorganic nutrients from discrete surface and bottom samples collected monthly for the period 2006-2020; 5) bottom temperature data collected the Wreck of Mars location by the MDMF over the period 1991-2021. There are four separate data sets included: 1) MDMF and CCS bottom dissolved oxygn from 2019; 2) CTD and ancillary data collected by WHOI in 2019; 3) CCS monthly survey data from 2011-2020; and 4) bottom temperature data collected by MDMF for 1991-2021. 1) MDMF/CCS dissolved oxygen data was collected from ship-based surveys using an YSI 6920 V2-2 data sonde; 2) WHOI CTD data was collected from vertical casts made from a small research vessel using an RBR CTD; 3) CCS CTD data was collected from vertical casts made from a small research vessel using a SeaBird Electronics CTD; 4) MDMF temperature data was collected from a bottom mounted temperature logger. Related Publications: Scully, M.E., W.R. Geyer, D. Borkman, T.L. Pouch, A. Costa, and O.C. Nichols, in press. Unprecedented summer hypoxia in southern Cape Cod Bay: An ecological response to regional climate change? Biogeosciences.
    Description: National Science Foundation - OCE- 2053240 NOAA Seagrant - NA20OAR4170506
    Keywords: Hypoxia ; Harmful Algal Blooms ; Climate Change ; Thermal stratification
    Repository Name: Woods Hole Open Access Server
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  • 10
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    North River estuary 2017 dataset (2021)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-05-26
    Description: These are the observational data collected in 2017 from the North River estuary. Data files include the long-term (LT) CTD and Aquadopp measurements from April to July, the short-term (STI from April to May and STII in late July) CTD measurements, eight shipboard CTD and ADCP surveys in April, May and July, the ADV measurements in late July, the North River mid-estuary region bathymetry, and the North River discharge (from USGS measurements).
    Description: National Science Foundation#1634480
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
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