Sea trial of the new datawell GPS directional waverider

Jeans, Gus; Bellamy, Ian; Vries, J. Jan de; Weert, P. van

doi:10.1109/ccm.2003.1194302

Cited by 22 publications

(12 citation statements)

References 1 publication

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“…The power density spectrum of a sawtooth wave follows an f −2 frequency power law, which is not limited by any upper frequency. Solutions depending on discarding all data from the spectra below a cut-off frequency will therefore not be sufficient, even though it has previously been used to remove erroneous lowfrequency data of a different type (Joodaki et al, 2013).…”

Section: The Wave Spectrummentioning

confidence: 99%

“…Nevertheless, there also exist several different technologies that use a GPS receiver to measure the displacement of the wave buoy, which have all been proven to be sufficiently accurate in a majority of situations (Herbers et al, 2012). Especially the technique using the Doppler shift of the GPS signal to measure the velocity of the wave buoy has been shown to produce excellent results when compared to an accelerometer-based Datawell Directional Waverider (DWR) ( de Vries et al, 2003;Jeans et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Removing low-frequency artefacts from Datawell DWR-G4 wave buoy measurements

Björkqvist¹,

Pettersson²,

Laakso³

et al. 2016

Geosci. Instrum. Method. Data Syst.

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Abstract. In this study we describe a previously unreported error in the vertical-displacement time series made with GPS-based Datawell DWR-G4 wave buoys and introduce a simple method to correct the resulting wave spectra. The artefact in the time series is found to resemble a sawtooth wave, which produces an erroneous trend following an f−2 power law in frequency space. The correction method quantifies the amount of erroneous trend below a certain maximum frequency and removes the spurious energy from all frequencies assuming the above-mentioned f−2 power law. The presented correction method is validated against an experimental field test, and its impact on the measured significant wave height is quantified. The method's sensitivity to the choice of the maximum frequency is also briefly discussed.

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Section: The Wave Spectrummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Removing low-frequency artefacts from Datawell DWR-G4 wave buoy measurements

Björkqvist¹,

Pettersson²,

Laakso³

et al. 2016

Geosci. Instrum. Method. Data Syst.

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“…Surface waves are traditionally measured fiom either a surface array of wires [3] or from a buoy that responds to the waves in heave [4] or by following the surface slope [5]. Where a ferry passes every two hours is a poor location for a surface array of wires or a wave buoy of either type.…”

Section: B Directional Wave Measurementsmentioning

confidence: 99%

Near bottom measurement of wave environment in a tidal current

Williams

Morrison

2005

Europe Oceans 2005

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Passenger ferries running from Woods Hole to Martha's Vineyard in Massachusetts eater Vineyard Sound at the Woods Hole Harbor entrance and turn from south to east where summer southwesterly winds oftea set up a short chop. Occasional stronger blows create a swell running across or opposed to the strong tidal current. Northeasters are common from October to May and set up a chop and swell at the Martha's Vineyard end of the passage as well as at the turning point off Woods Hole. Directional wave measurements were made for the Woods Hole and Martha's Vineyard Steamship Authority in June and July 2004 to characterize the wave climate for design of a new fast ferry that will serve this route.Heavy boat traffic makes surface buoys at the critical turning region impractical but shallow depths permit a directional wave spectrum to be computed from near bottom measurements of vector velocity and pressure. However the strong tidal currents add a new element to the computational task of projecting near bottom wave velocities back to the surface. In extreme cases, the wave period observed at the bottom may be very long when the waves propagate into the current yet the attenuation relation for waves near the bottom must use the wave period rehtive to the near surface moving water. This back tracking of current presents a problem that has not been well addressed by existing wave models. In the Vineyard Sound case, shallow depths and unstratitied conditions permit a computation of the surface current from the near bottom measurements for this reconstruction.

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“…In recent years, The Global Positioning System (GPS) technology has been introduced in wave buoys as an alternative to motion package based instruments, which utilize gimballed or strapped down accelerometers along with a compass to measure the pitch, heave and roll of the buoy (Krogstad et al, 1997;Krogstad et al, 1999;Herbers et al, 2012). Modern GPS receivers have improved the performance of GPS-based wave buoys, which have become a robust alternative to traditional wellestablished motion-sensor based sensors such as the Datawell Directional Waverider MKII (DWR-2) and newer generation DWR-3 (De Vries et al, 2003;Jeans et al, 2003;Colbert, 2010;Herbers et al, 2012). The GPS technology is also used to obtain the geo-location of Lagrangian Surface Velocity program (SVP) drifters used to measure the world ocean surface circulation (Niiler, 2001;Maximenko et al, 2013 and for other heavily instrumented drifting buoys designed for nearshore or surf-zone applications (e.g.…”

Section: Introductionmentioning

confidence: 99%

A New Strategic Wave Measurement Station Off Naples Port Main Breakwater

Centurioni

Braasch

Lauro

et al. 2017

Int. Conf. Coastal. Eng.

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The accuracy of directional wave spectra sensors is crucial for obtaining accurate forecasts of ocean and coastal wave conditions for scientific and engineering applications. In this paper, a newly designed, low-cost GPS-based wave buoy, called the Directional Wave Spectra Drifter (DWSD), is presented. A field test campaign was conducted at the Gulf of Naples, Italy with the goal of comparing the directional wave properties obtained with the DWSD and with a nearly co-located bottom-mounted Acoustic Doppler Current Profiler (ADCP) from Teledyne RD-Instruments. The comparison shows a very good agreement between the two methodologies. The reliability of this innovative instrument and its low costs allow a large variety of applications, including the implementation of a global, satellitelinked, real-time open-ocean network of drifting directional wave spectra sensors and monitoring the sea-state in harbors to aid ship transit and for planning coastal and offshore constructions. The DWSD is currently in use to better constrain the wave energy climatology with the goal of optimizing the design of a full-scale prototype Wave Energy Converter (WEC) in the port of Naples, Italy.

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Sea trial of the new datawell GPS directional waverider

Cited by 22 publications

References 1 publication

Removing low-frequency artefacts from Datawell DWR-G4 wave buoy measurements

Removing low-frequency artefacts from Datawell DWR-G4 wave buoy measurements

Near bottom measurement of wave environment in a tidal current

A New Strategic Wave Measurement Station Off Naples Port Main Breakwater

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