scholarly journals Observing Directional Properties of Ocean Swell with an Acoustic Doppler Current Profiler (ADCP)

2010 ◽  
Vol 27 (1) ◽  
pp. 210-225 ◽  
Author(s):  
T. H. C. Herbers ◽  
S. J. Lentz
Keyword(s):  
Continental Shelf ◽  
Acoustic Doppler Current Profiler ◽  
Parametric Estimation ◽  
Monitoring Applications ◽  
Current Profiler ◽  
Adcp Measurements ◽  
Directional Wave ◽  
Acoustic Doppler Current Profilers ◽  
Good Agreement

Abstract Acoustic Doppler current profilers (ADCPs) are widely used for routine measurements of ocean currents and waves in coastal environments. These instruments have the basic capability to measure surface wave frequency–directional spectra, but the quality of the estimates is not well understood because of the relatively high noise levels in the velocity measurements. In this study, wave data are evaluated from two 600-kHz ADCP instruments deployed at 20- and 45-m depths on the Southern California continental shelf. A simple parametric estimation technique is presented that provides robust estimates of the gross directional wave properties, even when the data quality is marginal, as was often the case in this benign wave environment. Good agreement of mean direction and (to a lesser degree) directional spreading estimates with measurements from a nearby surface-following buoy confirms that reliable wave information can generally be extracted from ADCP measurements on the continental shelf, supporting the instrument’s suitability for routine wave-monitoring applications.

scholarly journals A NEW STRATEGIC WAVE MEASUREMENT STATION OFF NAPLES PORT MAIN BREAKWATER

2017 ◽  
pp. 36 ◽  
Author(s):  
Luca Centurioni ◽  
Lance Braasch ◽  
Enrico Di Lauro ◽  
Pasquale Contestabile ◽  
Francesco De Leo ◽  
...  
Keyword(s):  
Wave Energy ◽  
Low Cost ◽  
Acoustic Doppler Current Profiler ◽  
Wave Spectra ◽  
Sea State ◽  
Gulf Of Naples ◽  
Current Profiler ◽  
Directional Wave ◽  
Low Costs ◽  
Good Agreement

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, satellite-linked, 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.

scholarly journals Thermal structure and circulation in Lake Chapala, Mexico

2016 ◽  
Vol 75 (s1) ◽  
Author(s):  
David Avalos-Cueva ◽  
Anatoliy Filonov ◽  
Iryna Tereshchenko ◽  
César O. Monzón ◽  
Federico Á. Velázquez-Muñoz
Keyword(s):  
Thermal Structure ◽  
Acoustic Doppler Current Profiler ◽  
Dry Season ◽  
Spatial Average ◽  
Average Temperature ◽  
Lake Chapala ◽  
Anticyclonic Gyre ◽  
Current Profiler ◽  
Adcp Measurements ◽  
Good Agreement

<p>This study analyzed and discussed the instrumental measurements of temperature and currents made on January 10, 2007, in Lake Chapala. We received new data on the formation of the thermocline. It is shown that the thermocline of the lake is formed only in the daytime and in a top-heated 0.5-1.0 m layer. The vertical temperature gradient reaches 2.5°C in the first meter, and the spatial average temperature across the lake showed that the northern end of the lake is, on average, 1°C warmer than the southern end. We numerically modelled the currents in the lake for the dry season using the HAMSOM 2D hydrodynamic model. The simulation results are in good agreement with the acoustic Doppler current profiler ADCP measurements. In the dry season, two gyres were found: a cyclonic gyre in the eastern part and an anticyclonic gyre in the western part.</p>

scholarly journals A Method for Processing Acoustic Doppler Current Profiler Velocity Data from Towed, Undulating Vehicles

2008 ◽  
Vol 25 (9) ◽  
pp. 1710-1716 ◽  
Author(s):  
Jiayi Pan ◽  
David A. Jay
Keyword(s):  
Surface Waters ◽  
High Frequency ◽  
Acoustic Doppler Current Profiler ◽  
Small Time ◽  
Ocean Current ◽  
Near Surface ◽  
Vertical Range ◽  
External Reference ◽  
Current Profiler ◽  
Adcp Measurements

Abstract The utility of the acoustic Doppler current profiler (ADCP) for sampling small time and space scales of coastal environments can be enhanced by mounting a high-frequency (1200 kHz) ADCP on an oscillating towed body. This approach requires both an external reference to convert the measured shears to velocities in the earth coordinates and a method to determine the towed body velocities. During the River Influence on the Shelf Ecosystems (RISE) project cruise, a high-frequency (1200 kHz) and narrowbeam ADCP with mode 12 sampling was mounted on a TRIAXUS oscillating towfish, which steers a 3D path behind the ship. This deployment approach extended the vertical range of the ADCP and allowed it to sample near-surface waters outside the ship’s wake. The measurements from a ship-mounted 1200-kHz narrowbeam ADCP are used as references for TRIAXUS ADCP data, and a method of overlapping bins is employed to recover the entire vertical range of the TRIAXUS ADCP. The TRIAXUS vehicle horizontal velocities are obtained by removing the derived ocean current velocity from the TRIAXUS ADCP measurements. The results show that the method is practical.

scholarly journals Divergence-Free Spatial Velocity Flow Field Interpolator for Improving Measurements from ADCP-Equipped Small Unmanned Underwater Vehicles

2012 ◽  
Vol 29 (3) ◽  
pp. 478-484 ◽  
Author(s):  
Jamie MacMahan ◽  
Ross Vennell ◽  
Rick Beatson ◽  
Jenna Brown ◽  
Ad Reniers
Keyword(s):  
Flow Field ◽  
Signal To Noise Ratio ◽  
Acoustic Doppler Current Profiler ◽  
Unmanned Underwater Vehicles ◽  
Velocity Magnitude ◽  
Velocity Flow ◽  
Current Profiler ◽  
Adcp Measurements ◽  
Measured Flow ◽  
Divergence Free

Abstract Applying a two-dimensional (2D) divergence-free (DF) interpolation to a one-person deployable unmanned underwater vehicle’s (UUV) noisy moving-vessel acoustic Doppler current profiler (MV-ADCP) measurements improves the results and increases the utility of the UUV in tidal environments. For a 3.5-h MV-ACDP simulation that spatially and temporally varies with the M2 tide, the 2D DF-estimated velocity magnitude and orientation improves by approximately 85%. Next the 2D DF method was applied to velocity data obtained from two UUVs that repeatedly performed seven 1-h survey tracks in Bear Cut Inlet, Miami, Florida. The DF method provides a more realistic and consistent representation of the ADCP measured flow field, improving magnitude and orientation estimates by approximately 25%. The improvement increases for lower flow velocities, when the ADCP measurements have low environmental signal-to-noise ratio. However, near slack tide when flow reversal occurs, the DF estimates are invalid because the flows are not steady state within the survey circuit.

scholarly journals Global Wavenumber Spectrum with Corrections for Altimeter High-Frequency Noise

2015 ◽  
Vol 45 (2) ◽  
pp. 495-503 ◽  
Author(s):  
Xiao-Hui Zhou ◽  
Dong-Ping Wang ◽  
Dake Chen
Keyword(s):  
High Frequency ◽  
Acoustic Doppler Current Profiler ◽  
High Energy ◽  
Frequency Noise ◽  
Spectral Estimates ◽  
Current Profiler ◽  
Adcp Measurements ◽  
Corrected Data ◽  
Geostrophic Turbulence ◽  
The Tropics

AbstractThe altimetry wavenumber spectra of sea surface height (SSH) provide a unique dataset for testing of geostrophic turbulence. While SSH spectral slopes of k−11/3 and k−5 are expected from theories and numerical simulations, the altimetry spectra from the original unfiltered and instrument noise–corrected data often are too shallow, falling between k−2 and k−3. In this study, the possibility that the flattened spectral slopes are partly due to contamination by unresolved high-frequency (<10 days) motions is tested. A spatiotemporal filter based on empirical orthogonal function expansion (EOF) is used to remove the temporally incoherent signals. The resulting spectral slopes are much steeper than in the previous studies. Over 70% of the revised global spectral estimates, excluding the tropics, are above k−3. Moreover, in high energy regions like the Gulf Stream and Kuroshio, the spectral slopes are about k−5, which is consistent with the classical quasigeostrophic (QG) turbulence. The spectral slopes are validated with the eddy kinetic energy (EKE) spectra from shipboard acoustic Doppler current profiler (ADCP) measurements in the high and low energy regions.

scholarly journals PARTICLE SIZE CHARACTERISTICS OF RIVERBED SEDIMENTS TRANSPORTED BY TIDAL BORE ‘BONO’ IN KAMPAR ESTUARY, RIAU-INDONESIA

2018 ◽  
Vol 43 (1) ◽  
pp. 25-35
Author(s):  
Wisnu Arya Gemilang ◽  
Ulung Jantama Wisha ◽  
Guntur Adhi Rahmawan
Keyword(s):  
Mass Transfer ◽  
Grain Size ◽  
Acoustic Doppler Current Profiler ◽  
Tidal Bore ◽  
Riverbed Sediments ◽  
Sediment Mass ◽  
Current Profiler ◽  
Adcp Measurements ◽  
Tidal Condition ◽  
Size Data

The presence of tidal bore in the Kampar River (locally known as ‘bono’) may influence sedimentation in the Kampar River and its estuary. Understanding sedimentation mechanisms (e.g., erosion, deposition) is important to communities along the Kampar River, which can be studied by analyzing characteristics of grain size distribution. Here, we study riverbed sediment samples collected from 17 stations using an Ekman grab sampler, accompanied by bathymetry and acoustic Doppler current profiler (ADCP) measurements. Grain size data show that the sediments are coarser upstream and gradually finer downstream. Silty sands are predominant in the upstream section of the river, sands in its river body and sandy silts in the downstream. The results indicate the influence of undular bores on grain size characteristics. We also found that the propagation of bono and Kampar River’s funnelshaped morphology cause intense scouring events of riverbed sediments. Sortation values that range between 0.332.14 suggest unstable currents that result in randomly deposited sediments. The sediment mass transfer per area is positively towards downstream at the low tidal condition. However, after the passage of the bores, the sediment mass transfer area becomes negatively towards upstream.

Acoustic Doppler Current Profiler (ADCP) Measurements of Breaking Waves

2008 ◽  
Author(s):  
Anne M. Fullerton ◽  
Thomas C. Fu
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Breaking Waves ◽  
Primary Objective ◽  
Breaking Wave ◽  
Flow Measurements ◽  
Measurement Systems ◽  
Bubble Density ◽  
Current Profiler ◽  
Adcp Measurements ◽  
Naval Surface Warfare

Detailed flow measurements of the turbulent multiphase flow associated with wave breaking present a unique instrumentation challenge. Measurement systems must be capable of high sampling rates, large dynamic ranges, and be capable of making measurements in water, air and optically opaque regions. An experiment was performed at the Naval Surface Warfare Center, Carderock Division, in October 2007 to measure various characteristics of the breaking wave generated from a submerged ship transom. The primary objective of this work was to obtain full-scale qualitative and quantitative flow field data of a large breaking transom wave over a range of conditions, specifically transom drafts and Froude numbers. Several types of measurements were made on the transom stern wave during this experiment, however, this paper will focus on the Nortek Acoustic Wave and Current (AWAC) profiler measurements of the stern wake. The AWAC has a center acoustic beam in addition to the three angled beams typically found on an acoustic Doppler current profiler. The trends of the acoustic return from the AWAC and the trends of the bubble density and location on the water surface compare well, and it is anticipated that this return can be related to void fraction and bubble measurements in the future. This type of non-intrusive measurement could be very useful in the evaluation of breaking waves.

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