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  • 1
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. 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 38 (2008): 2341-2357, doi:10.1175/2008JPO3986.1.
    Description: Onshore volume transport (Stokes drift) due to surface gravity waves propagating toward the beach can result in a compensating Eulerian offshore flow in the surf zone referred to as undertow. Observed offshore flows indicate that wave-driven undertow extends well offshore of the surf zone, over the inner shelves of Martha’s Vineyard, Massachusetts, and North Carolina. Theoretical estimates of the wave-driven offshore transport from linear wave theory and observed wave characteristics account for 50% or more of the observed offshore transport variance in water depths between 5 and 12 m, and reproduce the observed dependence on wave height and water depth. During weak winds, wave-driven cross-shelf velocity profiles over the inner shelf have maximum offshore flow (1–6 cm s−1) and vertical shear near the surface and weak flow and shear in the lower half of the water column. The observed offshore flow profiles do not resemble the parabolic profiles with maximum flow at middepth observed within the surf zone. Instead, the vertical structure is similar to the Stokes drift velocity profile but with the opposite direction. This vertical structure is consistent with a dynamical balance between the Coriolis force associated with the offshore flow and an along-shelf “Hasselmann wave stress” due to the influence of the earth’s rotation on surface gravity waves. The close agreement between the observed and modeled profiles provides compelling evidence for the importance of the Hasselmann wave stress in forcing oceanic flows. Summer profiles are more vertically sheared than either winter profiles or model profiles, for reasons that remain unclear.
    Description: This research was funded by the Ocean Sciences Division of the National Science Foundation under Grants OCE-0241292 and OCE-0548961.
    Keywords: Continental shelf ; Transport ; Shear structure/flows ; Coastal flows ; Gravity waves
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 2
    Publication Date: 2023-01-30
    Description: Research data from the Field Research Facility (FRF) http://www.frf.usace.army.mil/
    Keywords: FRF
    Type: Dataset
    Format: application/zip, 7 datasets
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  • 3
    Publication Date: 2023-01-30
    Description: USACE / FRF has maintained wave buoys around the 17 m and/or 20 m depth contour since 1980. Over the years, we have used three different types of waverider buoys manufactured by Datawell B.V. (Haarlem, Netherlands). From 1980 until 1996, we used non-directional buoys, first the 0.7 m hull diameter design and then the 0.9 m hull diameter design. The buoys operate by recording the output of an accelerometer suspended in fluid and gimbaled (Hippy-40). For data prior to September 1986, data were recorded at 2 or 4 Hz and record lengths were either 34 or 17 minutes, respectively. Collection intervals were either three hours or six hours. From September 1986 to November 1996 data was collected hourly. Frequency spectra were computed using the Welch method with 50% overlapped ensembles [1]. From the end of 1996 onward, we have maintained 0.9 m hull diameter Directional Waverider MkII and MKIII buoys [2] that, in addition to vertical acceleration, also measure two orthogonal components of horizontal acceleration. From Feb 1997 to May 2005, time series were collected at 1.28 Hz and cross-spectral analysis was performed on shore [3, 4]. Between May 2005 and May 2013, directional Fourier coefficients computed on-board the buoy and transmitted onshore. Since May 2013, data analysis has been manged through the Coastal Data Information Program (CDIP), UCSD San Diego, CA. Data are transmitted via an Iridium satellite link at half-hour intervals. Two dimensional (2D) frequency-direction spectra are computed using an Iterative Maximum Likelihood Estimator (IMLE) method [5]. For more information see FRF data paper, FRF website and data portal, and CDIP website. [1] Welch, P (1967) [2] de Vries, JJ (2014) [3] Longuet-Higgins, M.S., Cartwright, D.E. and Smith, N.D. (1963) [4] Earle, M.D., Steele, K.E. and Wang, D.W.C. (1999) [5] Oltman-Shay, J. and Guza, R.T. (1984)
    Keywords: coastal wave; CT; Field_Research_Facility; FRF; North Carolina; ocean wave; significant wave height; Underway cruise track measurements; wave; wave buoy; wave spectra
    Type: Dataset
    Format: application/x-netcdf, 4.7 MBytes
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  • 4
    Publication Date: 2023-01-30
    Description: This data include a unique series of repetitive surveys (1979-now) of shore-perpendicular profile lines surrounding the US Army Corps of Engineers (USACE) Field Research Facility (FRF) in Duck, NC. The surveys typically include 28 lines which extend from 600 m south of the FRF research pier to 600 m north. Special surveys may extend the coverage further. Surveys are typically monthly and after major storms but may be done as frequently as daily during special experiments (DUCK82, DUCK85, SuperDuck '86, DELILAH '90, DUCK94, SandyDuck 1997, DUCK98 and MORPHOS 2008, etc.). Profile lines are spaced ~45 m apart and extend from the primary dune line to approximately 2 km offshore (-15 m isobath NAVD88). Profile lines are numbered according to their FRF coordinate longshore distance in meters. 4 lines (1097, 1006, 1 and -91) were surveyed biweekly until ~2007. During the experiments, surveys were conducted more frequently of an area located north of the pier and known as the "minigrid" where profile line spacing was ~25 m. Over time the survey techniques evolved; accuracy and data point coverage improved. The platforms used include: (1) A Sea Sled with a graduated mast which was pulled offshore by a boat and winched back to shore by means of a cable; (2) The Coastal Research Amphibious Buggy or CRAB, a 10-m tall motorized tripod which an operator drives from the beach through the surf zone to a depth of ~-9 m at ~1000m offshore. (3) A Lighter Amphibious Resupply Cargo V (LARC-V) vessel which is a 10-m long amphibious vessel capable of continuous data collection from the beach, through the surf zone and offshore. LARC-V surveys extend to a depth of ~-15 m at ~2000 m offshore. Survey instruments included a Motorola Miniranger, Automatic Survey Level, Zeiss Elta 2s Electronic Total Station, Geotronics Geodimeter 140T auto-tracking total station and most recently a Real-Time Kinematic Global Positioning System (RTK-GPS). Speed, accuracy and error sources depend on the survey system used. These data are part of a series of surveys since October 1979 which document the evolving beach topography and bathymetry surrounding the USACE Field Research Facility (FRF) and which provide a measure of the beach's response to coastal processes, including storms. Survey data are complemented by a suite of continuous observations of local waves, winds, tides and currents. These data are unique in their temporal coverage and vertical accuracy and have been the subject of multiple technical papers. For more information and technical details, please see the PDF embedded with the data files (or see further details reference).
    Keywords: CT; Field_Research_Facility; File content; File format; File name; File size; FRF; North Carolina; Underway cruise track measurements; Uniform resource locator/link to file
    Type: Dataset
    Format: text/tab-separated-values, 10 data points
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  • 5
    Publication Date: 2023-01-30
    Description: USACE / FRF has maintained wave buoys around the 17 m and/or 20 m depth contour since 1980. Over the years, we have used three different types of waverider buoys manufactured by Datawell B.V. (Haarlem, Netherlands). From 1980 until 1996, we used non-directional buoys, first the 0.7 m hull diameter design and then the 0.9 m hull diameter design. The buoys operate by recording the output of an accelerometer suspended in fluid and gimbaled (Hippy-40). For data prior to September 1986, data were recorded at 2 or 4 Hz and record lengths were either 34 or 17 minutes, respectively. Collection intervals were either three hours or six hours. From September 1986 to November 1996 data was collected hourly. Frequency spectra were computed using the Welch method with 50% overlapped ensembles [1]. From the end of 1996 onward, we have maintained 0.9 m hull diameter Directional Waverider MkII and MKIII buoys [2] that, in addition to vertical acceleration, also measure two orthogonal components of horizontal acceleration. From Feb 1997 to May 2005, time series were collected at 1.28 Hz and cross-spectral analysis was performed on shore [3, 4]. Between May 2005 and May 2013, directional Fourier coefficients computed on-board the buoy and transmitted onshore. Since May 2013, data analysis has been manged through the Coastal Data Information Program (CDIP), UCSD San Diego, CA. Data are transmitted via an Iridium satellite link at half-hour intervals. Two dimensional (2D) frequency-direction spectra are computed using an Iterative Maximum Likelihood Estimator (IMLE) method [5]. For more information see FRF data paper, FRF website and data portal, and CDIP website. [1] Welch, P (1967) [2] de Vries, JJ (2014) [3] Longuet-Higgins, M.S., Cartwright, D.E. and Smith, N.D. (1963) [4] Earle, M.D., Steele, K.E. and Wang, D.W.C. (1999) [5] Oltman-Shay, J. and Guza, R.T. (1984)
    Keywords: coastal waves; CT; directional wave data; Field_Research_Facility; FRF; North Carolina; ocean waves; Underway cruise track measurements; wave; wave buoy; wave spectra
    Type: Dataset
    Format: application/x-netcdf, 2.2 GBytes
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  • 6
    Publication Date: 2023-01-30
    Description: By 1986, FRF scientists and technicians designed and built a novel wave sensor. A fixed, precisely-surveyed array of pressure gauges working in sync forming a wave antennae with a directional resolution well beyond that of buoys; details can be found in [1]. From 1986 - 1990, the array consisted of 10 elements parallel to the shore, referred to as the "linear array". The linear array resolved directional spectra but with 180 degree ambiguity. Although most of the wave energy propagates towards the coast, there is some fraction of reflected wave energy (not resolved). Please see the FRF data paper, FRF website, and FRF data portal for more information. [1] Long, C. E. and Oltman-Shay, J. M. (1991)
    Keywords: coastal waves; CT; directional waves; Field_Research_Facility; FRF; linear array; North Carolina; ocean waves; Underway cruise track measurements; wave; wave array; wave data; wave measurement; wave spectra
    Type: Dataset
    Format: application/x-netcdf, 57.2 MBytes
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  • 7
    Publication Date: 2023-01-30
    Description: Over time, wind data has been recorded at 10+ distinct wind stations often with multiple stations active simultaneously. The highest quality records were selected to be included into a conglomerate. From 1981-1987, station locations included a tower near the main building and the roof of the main building. In 1987, measurements were additionally made at the end of the pier and, in 1994, the pier became their exclusive location. At each station, wind speed and direction were measured by either Weather Measure Skyvane anemometers or RM Young (RMY) marine anemometers. Both were mechanical anemometers whereby the action of the wind turns an impeller. In the early era, there was a gauge preference based on location (e.g., the pier location was preferred over the roof). In the modern era of multiple wind stations at the end of the pier, an algorithm chose a preferred station. Wind stations, and their preference, are listed in the Scientific Data paper. Most recently, station 1 or 2 is given preference depending on wind direction (the upwind sensor is preferred). If data from the preferred station passes QC, it is included in the conglomerate. If not, the same process is applied down the chain of preference until a record passes (stations 5 and 8 were never used). Wind speed and direction were recorded a 1 or 2 Hz with various record lengths. There are 3 main eras of sampling. Sampling schemes varied until near continuous sampling began in 1992. All previous sampling schemes were reanalyzed into 10 minute segments for calculating statistics. Record remainders are kept if they are at least 6 minutes but forced to 10 minute time steps. Data is in a netCDF file with variables (units): time (seconds), latitude (deg. N), longitude (deg. W), sensorID, sensorElevation (m), windSpeed (m/s), windGust (m/s), windDirection (deg.), qcFlagSpeed, qcFlagDirection. time is unix epoch time, sensorID is digit code representing unique ID and sensor preference, sensorElevation is relative to NAVD88, windSpeed is 10 minute average, windGust is highest 5 second average, windDirection is coming from convention - clockwise from true North, qcFlagSpeed & qcFlagDirection are indications of data quality - 1 = passed, 3 = questionable, and 4 = fail. Please see the paper for full documentation.
    Keywords: CT; Field_Research_Facility; FRF; North Carolina; Underway cruise track measurements; wind; wind direction; wind gust; wind speed
    Type: Dataset
    Format: application/x-netcdf, 26.9 MBytes
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  • 8
    Publication Date: 2023-01-30
    Description: USACE / FRF has maintained wave buoys around the 17 m and/or 20 m depth contour since 1980. Over the years, we have used three different types of waverider buoys manufactured by Datawell B.V. (Haarlem, Netherlands). From 1980 until 1996, we used non-directional buoys, first the 0.7 m hull diameter design and then the 0.9 m hull diameter design. The buoys operate by recording the output of an accelerometer suspended in fluid and gimbaled (Hippy-40). For data prior to September 1986, data were recorded at 2 or 4 Hz and record lengths were either 34 or 17 minutes, respectively. Collection intervals were either three hours or six hours. From September 1986 to November 1996 data was collected hourly. Frequency spectra were computed using the Welch method with 50% overlapped ensembles [1]. From the end of 1996 onward, we have maintained 0.9 m hull diameter Directional Waverider MkII and MKIII buoys [2] that, in addition to vertical acceleration, also measure two orthogonal components of horizontal acceleration. From Feb 1997 to May 2005, time series were collected at 1.28 Hz and cross-spectral analysis was performed on shore [3, 4]. Between May 2005 and May 2013, directional Fourier coefficients computed on-board the buoy and transmitted onshore. Since May 2013, data analysis has been manged through the Coastal Data Information Program (CDIP), UCSD San Diego, CA. Data are transmitted via an Iridium satellite link at half-hour intervals. Two dimensional (2D) frequency-direction spectra are computed using an Iterative Maximum Likelihood Estimator (IMLE) method [5]. For more information see FRF data paper, FRF website and data portal, and CDIP website. [1] Welch, P (1967) [2] de Vries, JJ (2014) [3] Longuet-Higgins, M.S., Cartwright, D.E. and Smith, N.D. (1963) [4] Earle, M.D., Steele, K.E. and Wang, D.W.C. (1999) [5] Oltman-Shay, J. and Guza, R.T. (1984)
    Keywords: coastal waves; CT; Field_Research_Facility; FRF; North Carolina; ocean waves; significant wave height; Underway cruise track measurements; wave; wave buoy; wave spectra
    Type: Dataset
    Format: application/x-netcdf, 9.5 MBytes
    Location Call Number Expected Availability
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  • 9
    Publication Date: 2008-11-01
    Description: Onshore volume transport (Stokes drift) due to surface gravity waves propagating toward the beach can result in a compensating Eulerian offshore flow in the surf zone referred to as undertow. Observed offshore flows indicate that wave-driven undertow extends well offshore of the surf zone, over the inner shelves of Martha’s Vineyard, Massachusetts, and North Carolina. Theoretical estimates of the wave-driven offshore transport from linear wave theory and observed wave characteristics account for 50% or more of the observed offshore transport variance in water depths between 5 and 12 m, and reproduce the observed dependence on wave height and water depth. During weak winds, wave-driven cross-shelf velocity profiles over the inner shelf have maximum offshore flow (1–6 cm s−1) and vertical shear near the surface and weak flow and shear in the lower half of the water column. The observed offshore flow profiles do not resemble the parabolic profiles with maximum flow at middepth observed within the surf zone. Instead, the vertical structure is similar to the Stokes drift velocity profile but with the opposite direction. This vertical structure is consistent with a dynamical balance between the Coriolis force associated with the offshore flow and an along-shelf “Hasselmann wave stress” due to the influence of the earth’s rotation on surface gravity waves. The close agreement between the observed and modeled profiles provides compelling evidence for the importance of the Hasselmann wave stress in forcing oceanic flows. Summer profiles are more vertically sheared than either winter profiles or model profiles, for reasons that remain unclear.
    Print ISSN: 0022-3670
    Electronic ISSN: 1520-0485
    Topics: Geosciences , Physics
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  • 10
    Publication Date: 2016-03-01
    Print ISSN: 1463-5003
    Electronic ISSN: 1463-5011
    Topics: Geography , Geosciences , Physics
    Published by Elsevier
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