Wave and current measurements in the Chesapeake Bay

Shih, H. H.; Bushnell, Mark; Tronvig, K.; Mero, T.

doi:10.1109/ccm.2003.1194326

“…The predominantly high level of agreement between wave-buoy-and ADCP-derived surface elevation spectra confirms previous studies in support of ADCP wave measurements (Terray et al 1990;Rørbaek and Anderson 2000;Jeans et al 2003;Shih et al 2003), which are generally based on integrated spectral parameters like H m0 and T m02 . Although in the present study the removal of the depth-incoherent part of the velocity oscillation did not yield a closer agreement between wave buoy and ADCP spectra, this may be different in shallow waters closer to the coast where flows are stronger and turbulence levels higher.…”

Section: Discussionsupporting

confidence: 73%

Field Verification of ADCP Surface Gravity Wave Elevation Spectra

Hoitink

¹

,

Peters²,

Schroevers³

2007

Journal of Atmospheric and Oceanic Technology

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Acoustic Doppler current profilers (ADCPs) can measure orbital velocities induced by surface gravity waves, yet the ADCP estimates of these velocities are subject to a relatively high noise level. The present paper introduces a linear filtration technique to significantly reduce the influence of noise and turbulence from energy spectra of combined orbital velocity measurements. Data were collected in 13-m-deep water with a 1.2-MHz ADCP sampling in mode 12, where a collocated wave buoy was used for verification. The surface elevation spectra derived from the filtrated and nonfiltrated measurements were compared with corresponding wave buoy spectra. In the frequency range between 0.12 and 0.5 Hz, ADCP-and wavebuoy-derived spectral estimates matched very well, even without applying the filtration technique. At frequencies below 0.12 Hz, the ADCP-derived surface elevation spectra are biased, caused by a depthvarying excess of spectral energy density in the measured orbital velocities, peaking at middepth. Internal waves may provide an explanation for the energy excess, as the experiment was conducted in the region of influence of the Rhine freshwater plume. Alternatively, infragravity waves may be the cause of the depth variation of low-frequency spectral energy density.

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“…In order to prepare for the establishment of new systems in nears shore regions where wave information is strongly desired but currently not available, CO-OPS has started to develop and test real-time currents and wave measurement systems featuring commonly available commercial-off-the-shelf acoustic sensors. To date, current and wave systems most recently developed and tested by CO-OPS have been based on bottom mounted, upward looking ADCP sensors [3,4]. One particular advantage of this system type is the capability to measure both parameters, simultaneously, using just one sensor mounted in a stable platform design.…”

Section: Introductionmentioning

confidence: 98%

NOAA’s recent field testing of current and wave measurement systems – part i

Heitsenrether

¹

,

Holcomb

²

,

Gray

³

et al. 2015

2015 IEEE/OES Eleveth Current, Waves and Turbulence Measurement (CWTM)

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The National Oceanic and Atmospheric Administration's (NOAA) Center for Operational Oceanographic Products and Services (CO-OPS) currently maintains twenty-two operational Physical Oceanographic RealTime System (PORTS®) observatories throughout the United States' coastal regions. Ocean current observations are among the multiple PORTS® data products that provide critical support for safe navigation and a variety of scientific and engineering applications. To ensure that its observing network provides the most accurate and up-to-date products available, CO-OPS routinely conducts test and evaluation of newly available oceanographic sensors and measurement systems. From October 10 -December 3, 2014, CO-OPS conducted a field test in the South Chesapeake Bay which included three acoustic current profiling and wave sensors deployed in bottom mounted, upward looking configuration 1) the TRDI 500 kHz Sentinel V, 2) the Nortek 600 kHz AWAC-AST, and 3) the Nortek 500 kHz Signature 500 AD2CP; and an AXYS Technologies TriAXYS TM directional wave buoy with current measurement capability provided by an integrated Nortek 600 kHz Aquadopp acoustic sensor. Also included in the deployment was a bottom mounted TRDI 600 kHz Workhorse Sentinel acoustic current profiling sensor. The test site was near the mouth of the bay where currents are predominantly tidal and the average water depth is approximately 15 meters (50 feet). During the test, currents at the site ranged in magnitude from approximately 0-0.75 m/s on a daily basis and reached as high as 1.2 m/s (2.3 knots) on one occasion. Also, three high wind storm events passed through the region and significant wave heights exceeded 2 m on multiple occasions. Data results presented in this paper focus on comparison of currents measured by two of the bottom mounted sensors, the TRDI Workhorse and Nortek AWAC, and the TriAXYS TM wave buoy's Nortek Aquadopp sensor. Currents measured by the bottom mounted AWAC and Workhorse sensors showed excellent agreement throughout the entire test; differences in principle current axis headings remained less than 5 degrees and root mean squared deviations (RMSD) between the measured current magnitudes were within 4-5 cm/s over all profile depths. Comparisons of currents measured by these two bottom mounted sensors and the TriAXYS TM buoy's Aquadopp sensor showed good agreement in current direction but comparisons between current magnitudes varied throughout the test. During the first 20 days, currents measured by bottom mounted sensors did not exceed 1 m/s and comparison between bottom versus buoy mounted sensors' magnitudes were excellent; RMSDs remained within 5-6 cm/s. However, over the final 34 days of the test when currents measured by bottom mounted sensors often exceeded 1 m/s, the bottom versus buoy mounted sensors' current magnitudeRMSDs were approximately twice as large, in the 11-14 cm/s range. Preliminary results provide no clear indication of significant effect of wave conditions on bottom versus buoy mounted ADCP comparisons. Rather the...

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“…The first three sensors are relatively new to CO-OPS and considered test systems, while the fourth (TRDI 600 kHz Workhorse) is commonly used throughout CO-OPS' National Current Observation Program (NCOP) and it is considered a reference in this case [2,3,4]. The primary objective of this test was to assess the suitability for use of new ADCP's in PORTS and NCOP current measurement systems.…”

Section: Introductionmentioning

confidence: 99%

NOAA’s recent field testing of current and wave measurement systems – part ii

Wilson¹,

Heitsenrether²,

Gray³

et al. 2015

2015 IEEE/OES Eleveth Current, Waves and Turbulence Measurement (CWTM)

View full text Add to dashboard Cite

The National Oceanic and Atmospheric Administration's (NOAA) Center for Operational Oceanographic Products and Services (CO-OPS) currently maintains twenty-two operational Physical Oceanographic Real-Time System (PORTS®) observatories throughout the United States' coastal regions. Ocean current observations are among the multiple PORTS® data products that provide critical support for safe navigation and a variety of scientific and engineering applications. To ensure that its observing network provides the most accurate and up-to-date products available, CO-OPS routinely conducts test and evaluation of newly available oceanographic sensors and measurement systems. From October 10 -December 3, 2014, CO-OPS conducted a field test in the South Chesapeake Bay which included three acoustic current profiling and wave sensors deployed in bottom mounted, upward looking configuration 1) the TRDI 500 kHz Sentinel V, 2) the Nortek 600 kHz AWAC-AST, and 3) the Nortek 500 kHz Signature 500 AD2CP; and an AXYS Technologies TriAXYS TM Next Wave II Directional Wave Buoy with Currents provided with an integrated Nortek 600 kHz Aquadopp acoustic sensor. Also included in the deployment was a bottom mounted TRDI 600 kHz Workhorse Sentinel acoustic current profiling sensor. The test site was near the mouth of the bay where currents are predominantly tidal and the average water depth is approximately 15 meters (50 feet). During the test, currents at the site ranged in magnitude from approximately 0-0.75 m/s on a daily basis and reached as high as 1.2 m/s (2.3 knots) on one occasion. Three high-wind storm events passed through the region and significant wave heights exceeded 2 m on multiple occasions. 978-1-4799-8419-0/15/$31.00 ©2015 IEEE

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Wave and current measurements in the Chesapeake Bay

Cited by 4 publications

References 4 publications

Field Verification of ADCP Surface Gravity Wave Elevation Spectra

Field Verification of ADCP Surface Gravity Wave Elevation Spectra

NOAA’s recent field testing of current and wave measurement systems – part i

NOAA’s recent field testing of current and wave measurement systems – part ii

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