NDBC's digital directional wave module

Teng, Chung-Chu; Bouchard, Richard; Riley, Rodney; Mettlach, Theodore; Dinoso, Richard; Chaffin, Joel

doi:10.23919/oceans.2009.5422386

Cited by 11 publications

(4 citation statements)

References 3 publications

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“…Sometime in the 1990s they began testing and implementing systems that were strapped down. Internal investigations by NDBC did not show a significant difference between the strappeddown and gimballed systems [Teng et al (2009) and an unpublished study referred to in R11]. The comparisons were limited to wave heights , 3.2-m H S .…”

Section: B Prevalencementioning

confidence: 94%

“…The Pacific Northwest is known for large waves produced by strong winter lows (e.g., Tillotson and Komar 1997). The strapped-down system used a MicroStrain 3DM-GX1 accelerometer (3DMG), processed with NDBC's Digital Directional Wave Module (DDWM) v2.0 (Teng et al 2009). The other system was a HIPPY 40 sensor processed by NDBC's Wave Processing Module (WPM) (Chaffin et al 1994).…”

Section: Methodsmentioning

confidence: 99%

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Tilt Error in NDBC Ocean Wave Height Records

Collins

Jensen

2022

Journal of Atmospheric and Oceanic Technology

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We identify and characterize an error in the National Data Buoy Center (NDBC) wave records due to the sustained tilt of a buoy under high winds. We use a standard, operational 3-m aluminum discus buoy from NDBC with two wave systems, one gimballed, and the other strapped-down but uncorrected. By comparing the two, we find that the most extreme waves are systematically overestimated. The overestimation is shown to be confined to a region around the peak frequency in the spectra: 0.05 - 0.15 Hz. Wave direction and directional spread are unaffected. A bias due to tilt error can be observed starting at winds of 10 m/s or wave heights of 4 m. The bias increases as a function of wind speed and wave height, i.e. the bias is +10% when winds are 20 m/s. Very high waves and winds are relatively rare, so while the tilt error does not affect overall statistics and basic analyses it could potentially affect analysis sensitive to the extremes. A correction is derived for significant wave height, which is a quadratic function of wind speed. The correction is shown to reduce wave heights in uncorrected records, but is found not appropriate for general use. There is evidence of tilt error at other NDBC stations, but the full extent of prevalence in the record is not known at this time.

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Section: B Prevalencementioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Tilt Error in NDBC Ocean Wave Height Records

Collins

Jensen

2022

Journal of Atmospheric and Oceanic Technology

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“…On the other hand, NDBC 3-and 2.1-m hulls are processed as surfacefollowing buoys (i.e., heave, and two slopes). In an effort to isolate the hull effects, evaluation sites were selected where the target NDBC 2.1-m hull and earlier 3-m hull wave data were collected using the same directional wave measurements system, the NDBC Digital Directional Wave Module (DDWM), version 3.04, and a triaxial MicroStrain 3DM-GX1 motion sensor (herewith referred to as DDWM; Teng et al 2009;Riley et al 2011).…”

Section: Performance Evaluations Methodsmentioning

confidence: 99%

Performance Evaluation of the Newly Operational NDBC 2.1-m Hull

Hall

Jensen

Wang

2022

Journal of Atmospheric and Oceanic Technology

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The importance of quantifying the accuracy in wave measurements is critical to not only understand the complexities of wind-generated waves, but imperative for the interpretation of implied accuracy of the prediction systems that use these data for verification and validation. As wave measurement systems have unique collection and processing attributes that result in large accuracy ranges, this work quantifies bias that may be introduced into wave models from the newly operational NOAA National Data Buoy Center (NDBC) 2.1-m hull. Data quality consistency between the legacy NDBC 3-m aluminum hulls and the new 2.1-m hull is compared to a relative reference, and provides a standardized methodology and graphical representation template for future intra-measurement evaluations. Statistical analyses and wave spectral comparisons confirm that the wave measurements reported from the NDBC 2.1-m hulls show an increased accuracy from previously collected NDBC 3-m hull wave data for significant wave height and average wave period, while retaining consistent accuracy for directional results, purporting that hull size does not impact NDBC directional data estimates. Spectrally, the NDBC 2.1-m hulls show an improved signal-to-noise ratio, allowing for increase in energy retention in the lower frequency spectral range, with an improved high frequency spectral accuracy above 0.25 Hz within the short seas and wind chop wave component regions. These improvements in both NDBC bulk and spectral data accuracy provide confidence for the wave community’s use of NDBC wave data to drive wave model technologies, improvements and validations.

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“…However, the bandwidths of the 47-band wave spectrum are Fig. 1 NDBC and WIS study sites 0.005 Hz, 0.01 Hz and 0.02 Hz for low-, middle-and highfrequency regions, respectively (detailed within Appendix B, NDBC 2003, 2018aTeng et al 2009).…”

Section: Moored Ndbc Buoy Datamentioning

confidence: 99%

Wave power trends along the U.S. coastline: in situ measurements and model hindcast estimates

2022

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Observational data are successfully assessed to investigate wave power (wave energy flux per unit of wave-crest) trends within four coastal regions around the US, a parameter that is deemed vital to those responsible for coastal protection and community resilience. This study tests for shifting observational inter-annual wave power trends using a newly developed, unique, United States Army Corps of Engineers Quality Controlled Consistent Measurement Archive, and offers a viable methodology to remove documented observational time series data discontinuations. This study is one of the first to show spatially and temporally comparative observational and model wave power results, providing new information on the accuracy of model wave power estimates, while showcasing in situ wave power trends at 29 sites around the U.S. coastline. Overall, the majority of the eastern Pacific Ocean and Hawaii wave power trends are downward, with mixed slope wave power trends apparent within the Atlantic Ocean and the Gulf of Mexico. Observational and model results are similar with respect to timing, but not magnitude, of wave power peaks in long-term inter-annual trends, with the moored buoy data presenting smaller wave power ranges for two (eastern Pacific Ocean and Hawaii) of the four regions. Additionally, the detection of a noticeable variability in the wave power trend direction within each region suggests that site-specific wave power trends should not be generalised to represent a large region. This work demonstrates that observational data are essential in local and regional wave climate studies to accurately estimate wave power for coastal planners and engineers.

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NDBC's digital directional wave module

Cited by 11 publications

References 3 publications

Tilt Error in NDBC Ocean Wave Height Records

Tilt Error in NDBC Ocean Wave Height Records

Performance Evaluation of the Newly Operational NDBC 2.1-m Hull

Wave power trends along the U.S. coastline: in situ measurements and model hindcast estimates

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