Analysis of WACSIS Data Using Directional HWM

2002 ◽  
Author(s):  
Jun Zhang ◽  
Shaosong Zhang ◽  
Zhongming Wang
Keyword(s):  
Wave Model ◽  
Ocean Waves ◽  
Wave Crest ◽  
Industrial Project ◽  
Wave Measurements ◽  
Wave Directionality ◽  
Directional Wave ◽  
Particle Velocities ◽  
Wave Properties ◽  
Field Wave

WACSIS (Wave Crest Sensor Inter-comparison Study) is a Joint Industrial Project (JIP). Many different types of instruments were attached to a steel jacket platform that located in 18 m deep water and about 9 km from the Dutch coast to measure ocean waves during this project. The sensors for measuring wave elevation include Marex and SAAB Radars, a Baylor wave staff, an EMI Laser, a Vlissingen and Marine 300 step gauges. A S4ADW current meter was deployed at 10m below the MWL to measure pressure and particle velocities. In addition, a Directional Waverider Buoy was deployed nearby the platform to provide the information of wave directionality. The Directional Hybrid Wave Model (DHWM) was recently developed to deterministically decompose and predict a directional wave field. By the DHWM, the wave properties nearby the platform can be deterministically predicted based on at least three wave measurements. If the prediction location happens to be same as other instruments whose measurements have not been used for the prediction, then the comparison between the prediction and the measurement by this instrument may reveal the consistency and suitability of this instrument. Several such kind of comparisons are given in this study, indicating the DHWM is valuable to the analysis of field wave measurements.

Analysis of WACSIS Data Using a Directional Hybrid Wave Model

2004 ◽  
Vol 126 (1) ◽  
pp. 60-65
Author(s):  
Jun Zhang ◽  
Shaosong Zhang ◽  
Zhongming Wang
Keyword(s):  
Wave Model ◽  
Wave Crest ◽  
Comparison Study ◽  
Hybrid Wave ◽  
Ocean Surface Waves ◽  
Wave Measurements ◽  
Different Types ◽  
Wave Sensors ◽  
A Current ◽  
Field Wave

The Wave Crest Sensor Inter-comparison Study (WACSIS) employed many different types of sensors to measure ocean surface waves. These sensors were attached to a steel jacket platform located in 18 m deep water about 9 km from the Dutch coast. To investigate the suitability and consistency of different wave sensors, wave characteristics at the locations of some sensors were deterministically predicted based on three other wave measurements using a Directional Hybrid Wave Model (DHWM). The comparisons between the predictions and related measurements were applied to the examination of the consistency among different sensors. As an example, a mistake of the orientation of a current meter has been found through the comparisons. This study also demonstrates that consistency among different types of wave sensors is satisfactory and the DHWM is valuable to the analysis of field wave measurements.

scholarly journals Quantifying wave measurement differences in historical and present wave buoy systems

2021 ◽  
Author(s):  
Robert Edward Jensen ◽  
Val Swail ◽  
Richard Harry Bouchard
Keyword(s):  
Complex Nature ◽  
Frequency Spectra ◽  
Measurement Systems ◽  
Wave Measurements ◽  
Directional Sensors ◽  
Wave Measurement ◽  
Western Us ◽  
Directional Wave ◽  
Wind Sea ◽  
Wave Properties

AbstractAn intra-measurement evaluation was undertaken, deploying a NOMAD buoy equipped with three National Data Buoy Center and two Environment and Climate Change Canada-AXYS sensor/payload packages off Monterey, California; a Datawell Directional Waverider buoy was deployed within 19 km of the NOMAD site. The six independent wave measurement systems reported hourly estimates of the frequency spectra, and when applicable, the four Fourier directional components. The integral wave parameters showed general agreement among the five sensors compared to the neighboring Datawell Directional Waverider, with the Inclinometer and the Watchman performing similarly to the more sophisticated 3DMG, HIPPY, and Triaxys sensor packages. As the Hm0 increased, all but the Inclinometer were biased low; however, even the Watchman reported reasonable wave measurements up to about 6–7 m, after which the Hm0 becomes negatively biased up to about a meter, comparable to previous studies. The parabolic fit peak spectral wave period, Tpp, results showed a large scatter, resulting from the complex nature of multiple swell wave systems compounded by local wind-sea development, exacerbated by a variable that can be considered as temporally unstable. The three directional sensors demonstrated that NOMAD buoys are capable of measuring directional wave properties along the western US coast, with biases of about 6 to 9 deg, and rms errors of approximately 30 deg. Frequency spectral evaluations found similarities in the shape, but a significant under estimation in the high frequency range. The results from slope analyses also revealed a positive bias in the rear face of the spectra, and a lack of invariance in frequency as suggested by theory.

An Atlas of the Wave-Energy Resource in Europe

1996 ◽  
Vol 118 (4) ◽  
pp. 307-309 ◽  
Author(s):  
M. T. Pontes ◽  
G. A. Athanassoulis ◽  
S. Barstow ◽  
L. Cavaleri ◽  
B. Holmes ◽  
...  
Keyword(s):  
Wave Energy ◽  
Energy Resource ◽  
Wave Model ◽  
Wave Climate ◽  
Weather Forecasts ◽  
Wave Measurements ◽  
Directional Wave ◽  
Offshore Wave ◽  
Climate Statistics

An atlas of the European offshore wave energy resource, being developed within the scope of a European R&D program, includes the characterization of the offshore resource for the Atlantic and Mediterranean coasts of Europe in addition to providing wave-energy and wave-climate statistics that are of interest to other users of the ocean. The wave data used for compiling the Atlas come from the numerical wind-wave model WAM, implemented in the routine operation of the European Centre for Medium Range Weather Forecasts (ECMWF), in addition to directional wave measurements from the Norwegian offshore waters.

ShorTCresT: Directional Wave Measurements at MARIN

2015 ◽  
Author(s):  
Janou Hennig ◽  
Jule Scharnke ◽  
Christian E. Schmittner ◽  
Joris van den Berg
Keyword(s):  
Good Description ◽  
Spectral Characteristics ◽  
Offshore Structures ◽  
Two Dimensions ◽  
Second Order ◽  
Wave Crest ◽  
Sea State ◽  
Wave Measurements ◽  
Directional Wave ◽  
Local Variability

The objective of the ShortCresT JIP Joint Industry Project was to take into account short-crestedness in the design of offshore structures against extreme waves based on a good description of their spectral characteristics, statistics, kinematics, breaking and loading and to deliver a concrete (empirical) design methodology. The second order wave crest distribution showed to be a good basis for the estimation of a design wave crest. However, depending on sea state steepness and directional spreading, crests may exceed the second order distribution in some severe seas by around 10 %. On the other hand, the very highest crests may be limited by breaking and even fall below the second order model. This paper addresses experimental results from the MARIN where directional wave measurements were carried out in two dimensions. Conclusions with respect to evolution of wave spectra in the basin, directional analysis and calibration, sampling variability, local variability of measured crest heights and measured crest height distributions due to different types of spreading are evaluated. Furthermore, the influence of the type of instrumentation and the effect of the spectral high frequency tail on the crest distributions are assessed.

scholarly journals Wave Directions in a Narrow Bay

2010 ◽  
Vol 40 (1) ◽  
pp. 155-169 ◽  
Author(s):  
Heidi Pettersson ◽  
Kimmo K. Kahma ◽  
Laura Tuomi
Keyword(s):  
Wave Model ◽  
Wave Climate ◽  
Spectral Peak ◽  
Step Size ◽  
Weakly Nonlinear ◽  
Spectral Wave Model ◽  
Directional Coupling ◽  
Directional Wave ◽  
The Baltic ◽  
The Waves

Abstract In slanting fetch conditions the direction of actively growing waves is strongly controlled by the fetch geometry. The effect was found to be pronounced in the long and narrow Gulf of Finland in the Baltic Sea, where it significantly modifies the directional wave climate. Three models with different assumptions on the directional coupling between the wave components were used to analyze the physics responsible for the directional behavior of the waves in the gulf. The directionally decoupled model produced the direction at the spectral peak correctly when the slanting fetch geometry was narrow but gave a weaker steering than observed when the fetch geometry was broader. The method of Donelan estimated well the direction at the spectral peak in well-defined slanting fetch conditions, but overestimated the longer fetch components during wave growth from a more complex shoreline. Neither the decoupled nor the Donelan model reproduced the observed shifting of direction with the frequency. The performance of the third-generation spectral wave model (WAM) in estimating the wave directions was strongly dependent on the grid resolution of the model. The dominant wave directions were estimated satisfactorily when the grid-step size was dropped to 5 km in the gulf, which is 70 km in its narrowest part. A mechanism based on the weakly nonlinear interactions is proposed to explain the strong steering effect in slanting fetch conditions.

scholarly journals Spectral shapes and parameters from three different wave sensors

2021 ◽  
Author(s):  
Anne Karin Magnusson ◽  
Robert Jensen ◽  
Val Swail
Keyword(s):  
Frequency Spectra ◽  
Measurement Systems ◽  
Wave Measurements ◽  
Climate Monitoring ◽  
Production Platform ◽  
Wave Sensors ◽  
Central North Sea ◽  
Wave Forecasting ◽  
Wave Properties

AbstractThe quality of wave measurements is of primary importance for the validation of wave forecasting models, satellite wave calibration and validation, wave physics, offshore operations and design and climate monitoring. Validation of global wave forecasts revealed significant regional differences, which were linked to the different wave buoy systems used by different countries. To fully understand the differences between the wave measurement systems, it is necessary to go beyond investigations of the integral wave parameters height, period and direction, into the frequency spectra and the four directional Fourier parameters that are used to estimate the directional distribution. We here analyse wave data measured from three different sensors (non-directional Datawell Waverider buoy, WaveRadar Rex, Optech laser) operating at the Ekofisk oil production platform located in the central North Sea over a period of several months, with significant wave height ranging from 1 to 10 m. In general, all three sensors provide similar measurements of the integral wave properties and frequency spectra, although there are some significant differences which could impact design and operations, forecast verification and climate monitoring. For example, the radar underestimates energy in frequency bands higher than 8 s by 3–5%, swell (12.5–16 s) by 5–13%, while the laser has 1–2% more energy than the Waverider in the most energetic bands. Lee effects of structures are also estimated. Lower energy at the frequency tail with the radar has an effect on wave periods (they are higher); wave steepness is seen to be reduced by 10% in the wind seas. Goda peakedness and the unidirectional Benjamin-Feir index are also examined for the three sensors.

scholarly journals Directional wave measurements using an autonomous vessel

2016 ◽  
Vol 66 (9) ◽  
pp. 1087-1098 ◽  
Author(s):  
Lars R. Hole ◽  
Ilker Fer ◽  
David Peddie
Keyword(s):  
Wave Measurements ◽  
Directional Wave ◽  
Autonomous Vessel

scholarly journals Evaluating skill of BMKG wave model forecast (Wavewatch-3) with observation data in Indian Ocean (5 – 31 December 2017).

2021 ◽  
Vol 893 (1) ◽  
pp. 012058
Author(s):  
R Kurniawan ◽  
H Harsa ◽  
A Ramdhani ◽  
W Fitria ◽  
D Rahmawati ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Wave Height ◽  
Model Performance ◽  
Forecast Accuracy ◽  
Wave Model ◽  
Ocean Waves ◽  
Observation Data ◽  
Operating Characteristics ◽  
Wave Forecast ◽  
Good For

Abstract Providing Maritime meteorological forecasts (including ocean wave information) is one of BMKG duties. Currently, BMKG employs Wavewatch-3 (WW3) model to forecast ocean waves in Indonesia. Evaluating the wave forecasts is very important to improve the forecasts skill. This paper presents the evaluation of 7-days ahead BMKG’s wave forecast. The evaluation was performed by comparing wave data observation and BMKG wave forecast. The observation data were obtained from RV Mirai 1708 cruise on December 5th to 31st 2017 at the Indian Ocean around 04°14'S and 101°31'E. Some statistical properties and Relative Operating Characteristics (ROC) curve were utilized to assess the model performance. The evaluation processes were carried out on model’s parameters: Significant Wave Height (Hs) and Wind surface for each 7-days forecast started from 00 UTC. The comparation results show that, in average, WW3 forecasts are over-estimate the wave height than that of the observation. The forecast skills determined from the correlation and ROC curves are good for the first- and second-day forecast, while the third until seventh day decrease to fair. This phenomenon is suspected to be caused by the wind data characteristics provided by the Global Forecasts System (GFS) as the input of the model. Nevertheless, although statistical correlation is good for up to 2 days forecast, the average value of Root Mean Square Error (RMSE), absolute bias, and relative error are high. In general, this verifies the overestimate results of the model output and should be taken into consideration to improve BMKG’s wave model performance and forecast accuracy.

Simulation of Hurricane Seas in a Multidirectional Wave Basin

1991 ◽  
Vol 113 (3) ◽  
pp. 219-227 ◽  
Author(s):  
A. Cornett ◽  
M. D. Miles
Keyword(s):  
Ocean Waves ◽  
Entropy Method ◽  
Wave Spectra ◽  
Single Wave ◽  
Wave Condition ◽  
Wave Basin ◽  
Wide Range ◽  
Directional Wave ◽  
Wave Conditions ◽  
Multidirectional Wave

This paper describes the generation and verification of four realistic sea states in a multidirectional wave basin, each representing a different storm wave condition in the Gulf of Mexico. In all cases, the degree of wave spreading and the mean direction of wave propagation are strongly dependent on frequency. Two of these sea states represent generic design wave conditions typical of hurricanes and winter storms and are defined by JONSWAP wave spectra and parametric spreading functions. Two additional sea states, representing the specific wave activity during hurricanes Betsy and Carmen, are defined by tabulated hindcast estimates of the directional wave energy spectrum. The Maximum Entropy Method (MEM) of directional wave analysis paired with a single-wave probe/ bi-directional current meter sensor is found to be the most satisfactory method to measure multidirectional seas in a wave basin over a wide range of wave conditions. The accuracy of the wave generation and analysis process is verified using residual directional spectra and numerically synthesized signals to supplement those measured in the basin. Reasons for discrepancy between the measured and target directional wave spectra are explored. By attempting to reproduce such challenging sea states, much has been learned about the limitations of simulating real ocean waves in a multidirectional wave basin, and about techniques which can be used to minimize the associated distortions to the directional spectrum.

scholarly journals Spatially Tracking Wave Events in Partitioned Numerical Wave Model Outputs

2019 ◽  
Vol 36 (10) ◽  
pp. 1933-1944 ◽  
Author(s):  
Haoyu Jiang
Keyword(s):  
Grid Point ◽  
Wave Model ◽  
Ocean Waves ◽  
Model Verification ◽  
Analysis Model ◽  
Wave Parameters ◽  
Numerical Wave ◽  
Wave Models ◽  
Spectral Partitioning ◽  
The Impact

AbstractNumerical wave models can output partitioned wave parameters at each grid point using a spectral partitioning technique. Because these wave partitions are usually organized according to the magnitude of their wave energy without considering the coherence of wave parameters in space, it can be difficult to observe the spatial distributions of wave field features from these outputs. In this study, an approach for spatially tracking coherent wave events (which means a cluster of partitions originating from the same meteorological event) from partitioned numerical wave model outputs is presented to solve this problem. First, an efficient traverse algorithm applicable for different types of grids, termed breadth-first search, is employed to track wave events using the continuity of wave parameters. Second, to reduce the impact of the garden sprinkler effect on tracking, tracked wave events are merged if their boundary outlines and wave parameters on these boundaries are both in good agreement. Partitioned wave information from the Integrated Ocean Waves for Geophysical and other Applications dataset is used to test the performance of this spatial tracking approach. The test results indicate that this approach is able to capture the primary features of partitioned wave fields, demonstrating its potential for wave data analysis, model verification, and data assimilation.

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