Wave Measurements at Eastern Green Canyon During Hurricane Ike

2009 ◽  
Author(s):  
Oriol Rijken ◽  
Adam Bangs
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Repetitive Sequences ◽  
Wave Crest ◽  
Hurricane Ike ◽  
Wave Trough ◽  
Wave Measurements ◽  
Wave Event ◽  
Measurement Location ◽  
Insight Into

Wave measurements were obtained at an Eastern Green Canyon location during hurricane Ike in September 2009. The eye of the hurricane passed approximately 68 nautical miles to the South West of the measurement location. The significant wave height was above 30 ft for about 20 hours and above 40 ft for about 5.5 hours. The wave time series provide an insight into the wave field as the storm approaches and leaves the location. One of the interesting features observed was that there were repetitive sequences, where each sequence consisted of a period of increased wave energy followed by periods of reduced wave energy. Each sequence lasted approximately one hour. Measured wave crest, wave trough and wave height distributions are discussed. One unique wave event was observed. This event was characterized by a predictably-sized crest followed by a very deep trough.

Statistical Analysis of a Set of Basin Waves

2011 ◽  
Author(s):  
Jule Scharnke ◽  
Janou Hennig
Keyword(s):  
Statistical Analysis ◽  
Wave Height ◽  
Water Depth ◽  
Water Waves ◽  
Rayleigh Distribution ◽  
Second Order ◽  
Distribution Functions ◽  
Wave Crest ◽  
Intermediate Water ◽  
Wave Measurements

In a recent paper the effect of variations in calibrated wave parameters on wave crest and height distributions was analyzed (OMAE2010-20304, [1]). Theoretical distribution functions were compared to wave measurements with a variation in water depth, wave seed (group spectrum) and location of measurement for the same initial power spectrum. The wave crest distribution of the shallow water waves exceeded both second-order and Rayleigh distribution. Whereas, in intermediate water depth the measured crests followed the second order distribution. The distributions of the measured waves showed that different wave seeds result in the same wave height and crest distributions. Measured wave heights were lower closer to the wave maker. In this paper the results of the continued statistical analysis of basin waves are presented with focus on wave steepness and their influence on wave height and wave crest distributions. Furthermore, the sampling variability of the presented cases is assessed.

Improving Offshore Platforms Wave Measurements

2013 ◽  
Author(s):  
George Z. Forristall ◽  
Alexia Aubault
Keyword(s):  
Wave Height ◽  
Inverse Method ◽  
Wave Spectrum ◽  
Wave Crest ◽  
Offshore Platforms ◽  
Structural Members ◽  
Incoming Wave ◽  
Wave Measurements ◽  
Diffracted Waves ◽  
Wave Elevations

Offshore platforms are equipped with wave instrumentation at deck extremities to measure incoming wave elevations. When those instruments are close to large structural members they record the diffracted wave as well as the incident wave. This paper studies the effect of the diffracted wave on the measured wave height. First and second order diffracted wave elevations are computed for a model Tension Leg Platform (TLP) that was tested in the Offshore Basin of the Maritime Research Institute Netherlands (MARIN) offshore basin as part of the CresT Joint Industry Project (JIP). Their respective contributions to the wave spectrum are compared at locations near the structure. These calculations are useful for identifying the best locations for wave probes. The diffraction solution is used in forward calculations to compute the wave height and wave crest at locations under the deck from the undisturbed wave. These calculations can be used to set the air gap under the deck. Conversely, this paper introduces an inverse method to retrieve the undisturbed wave height and crest from the measured data by inverting the diffracted wave coefficients. The calculations are verified using measurements of undisturbed and diffracted waves under the TLP model. This work was sponsored by the Climatology and Simulation of Eddies (CASE) JIP.

scholarly journals Wave height return periods from combined measurement–model data: a Baltic Sea case study

2020 ◽  
Vol 20 (12) ◽  
pp. 3593-3609
Author(s):  
Jan-Victor Björkqvist ◽  
Sander Rikka ◽  
Victor Alari ◽  
Aarne Männik ◽  
Laura Tuomi ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Wave Height ◽  
Return Period ◽  
Measurement Model ◽  
Model Data ◽  
Northerly Wind ◽  
Sampling Variability ◽  
Wave Measurements ◽  
Low Pass ◽  
Wave Event

Abstract. This paper presents how to account for the lack of sampling variability in model data when they are combined with wave measurements. We addressed the dissimilarities between the types of data by either (i) low-pass filtering the observations or (ii) adding synthetic sampling variability to the model. Measurement–model times series combined with these methods served as the basis for return period estimates of a high wave event in January 2019. During this storm northerly wind speeds in the Baltic Sea rose to 32.5 m s−1 and an unprecedented significant wave height of 8.1 m was recorded in the Bothnian Sea sub-basin. Both methods successfully consolidated the combined time series but produced slightly different results: using low-pass-filtered observations gave lower estimates for the return period than using model data with added sampling variability. Extremes in both types of data followed the same type of theoretical distributions, and our best estimate for the return period was 104 years (95 % confidence 39–323 years). A similar wave event can potentially be more likely in the future climate, and this aspect was discussed qualitatively.

Comparative wave measurements at a wave energy site with a recently developed low-cost wave buoy (Spotter), ADCP and pressure loggers

2021 ◽  
Author(s):  
Orrin Lancaster ◽  
Remo Cossu ◽  
Sebastien Boulay ◽  
Scott Hunter ◽  
Tom E. Baldock
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Significant Wave Height ◽  
Low Cost ◽  
Wave Period ◽  
Wave Direction ◽  
Mean Values ◽  
Significant Wave ◽  
Wave Measurements ◽  
The Mean

AbstractWave measurements from a new, low-cost, real-time wave buoy (Spotter) are investigated in a comparative study as part of a site characterization study at a wave energy candidate site at King Island, Tasmania, Australia. Measurements from the Sofar Ocean Spotter buoy are compared with concurrent measurements from a Teledyne RD Instrument (RDI) 1200 kHz Work Horse ADCP and two RBRsolo3 D wave16 pressure loggers. The comparison period between 8th August – 12th October 2019 provides both the shallowest and longest continuous published comparison undertaken with the Spotter buoy.Strong agreement was evident between the Spotter buoy and RDI ADCP of key wave parameters including the significant wave height, peak wave period, and mean wave direction, with the mean values of those parameters across the full deployment period agreeing within 3%. Surface wave spectra and directional spectra are also analyzed with good agreement observed over the majority of the frequency domain, although the Spotter buoy records approximately 17% less energy within a narrow frequency band near the peak frequency when compared to the RDI ADCP. Measurements derived from the pressure loggers routinely underestimated the significant wave height and overestimated the mean wave period over the deployment period. The comparison highlights the suitability of the Spotter buoy for low-cost wave resource studies, with accurate measurements of key parameters and spectra observed.

scholarly journals MORPHOLOGY AND DYNAMICS OF CRESCENTIC BAR SYSTEMS

1982 ◽  
Vol 1 (18) ◽  
pp. 59
Author(s):  
V. Goldsmith ◽  
D. Bowman ◽  
K. Kiley ◽  
B. Burdick ◽  
Y. Mart ◽  
...  
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Field Studies ◽  
Wave Climate ◽  
Phase Correlation ◽  
Mature Stage ◽  
Wave Direction ◽  
Significant Wave ◽  
Wave Measurements ◽  
Wave Heights

Aerial photograph and field studies in the southeastern Mediterranean, involving bathymetric mapping, and concurrent and antecedent wave measurements, have been used to delineate the sequential development of crescentic bars and associated dynamics. The bar sequence includes multiple parallel or wavy bars, ridge and runnels, oblique/transverse bars, single crescentic and double crescentic bars, and occurs during a calming down of wave activity from 2.5 to 0.5 m waves. The concomitant wave data, including wave directions, energy spectrum, significant wave height, and length of the calm period, showed strong correlation with the bar stages. An increase in total bar occurrence during summer is related to a major wave energy decrease in the spring, when significant wave heights (H ) < 1 m sharply increase to 70-85% in April-May. Inner single crescentic and initial double-crescentic bars are largely restricted to the calmest wave months of May/April to October/November, which reflects their sensitivity to wave energy. The aseasonal occurrence is best shown by the mature double crescentic type, which apparently is the final stage in the crescentic bar development sequence. Two bar developmental sequences were delineated: one shore-normal and the other initially oblique, but gradually rotating to shore-normal in the mature stage. Out of phase relationships between inner and outer bar systems resulted from the lag in response of the outer bars behind changes in wave direction. Among the inner crescentic bars and shore rhythms, phase-correlation was the rule. Crescentic bars are well developed on this coast because of the dissipative conditions and the distinct wave climate. High waves in the winter remove the existing bars, and extended calms allow the full development of the crescentic bar sequence. Similar bar types occur on different coasts in different sequences and in different proportions of time. Thus, it is suggested that these differences are attributable to global differences in the occurrences of threshold wave height conditions .

scholarly journals Wave height return periods from combined measurement–model data: A Baltic Sea case study

2020 ◽  
Author(s):  
Jan-Victor Björkqvist ◽  
Sander Rikka ◽  
Victor Alari ◽  
Aarne Männik ◽  
Laura Tuomi ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Wave Height ◽  
Return Period ◽  
Measurement Model ◽  
Model Data ◽  
Northerly Wind ◽  
Sampling Variability ◽  
Wave Measurements ◽  
Low Pass ◽  
Wave Event

Abstract. This paper presents how to account for the lack of sampling variability in model data when they are combined with wave measurements. We addressed the dissimilarities between the types of data by either: i) low-pass filtering the observations or ii) adding synthetic sampling variability to the model. Measurement–model times series combined with these methods served as the basis for return period estimates of a high wave event in January 2019. During this storm northerly wind speeds in the Baltic Sea rose to 32.5 m s−1 and an unprecedented significant wave height of 8.1 m was recorded in the Bothnian Sea sub-basin. Both methods successfully consolidated the combined time series but produced slightly different results: using low-pass filtered observations gave lower estimates for the return period than using model data with added sampling variability. Extremes in both types of data followed the same type of theoretical distributions, and our best estimate for the return period was 104 years (95 % confidence 39–323 years). A similar wave event can potentially be more likely in the future climate, and this aspect was discussed qualitatively.

Optimization of Power Absorption From Sea Waves

1979 ◽  
Vol 101 (2) ◽  
pp. 145-152 ◽  
Author(s):  
A. Baz ◽  
M. Ezz ◽  
M. S. Bayoumi
Keyword(s):  
Wave Energy ◽  
Simple Wave ◽  
Wave Crest ◽  
Design Parameters ◽  
Wave Power ◽  
Sea Waves ◽  
Power Absorption ◽  
Optimum Load ◽  
Wave Trough ◽  
Sea Wave

This article presents a generalized procedure for selecting rationally the design parameters of a simple wave power absorption system. The system utilizes a tethered-symmetrical float which rides the sea waves and transmits the wave energy to a viscously damped load. The optimum load levels corresponding to the different sea states are determined, for several float geometries, in order to maximize the overall efficiency of wave-power conversion. The optimum float dimensions are constrained to guarantee that the float will not leave the wave crest during its upward travel or sink below the wave trough as it goes downward. These constraints, if overlooked, as has been the case so far in the literature, result not only in improper functioning of the system but also in values of the conversion efficiency higher than reality. The developed procedure predicts also, for different float configurations, the limits that, if satisfied, can guarantee that the system would operate at its maximum possible efficiency irrespective of the sea wave conditions. Therefore, the material presented in the study can be extremely useful in designing efficient wave power absorbers which would help in capturing the vast amount of the renewable and nonpolluting sea wave energy.

UNDERWATER BARRED BEACH PROFILE TRANSFORMATION UNDER DIFFERENT WAVES CONDITIONS

2017 ◽  
Author(s):  
Olga Kuznetsova ◽  
Olga Kuznetsova ◽  
Yana Saprykina ◽  
Yana Saprykina ◽  
Boris Divinsky ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Coastal Zone ◽  
Wave Height ◽  
Wave Energy ◽  
Wave Period ◽  
Beach Profile ◽  
Infragravity Waves ◽  
Wave Parameters ◽  
Mean Wave Period

Based on numerical modelling evolution of beach under waves with height 1,0-1,5 m and period 7,5 and 10,6 sec as well as spectral wave parameters varying cross-shore analysed. The beach reformation of coastal zone relief is spatially uneven. It is established that upper part of underwater beach profile become terraced and width of the terrace is in direct pro-portion to wave height and period on the seaward boundary but inversely to angle of wave energy spreading. In addition it was ascertain that the greatest transfiguration of profile was accompanied by existence of bound infragravity waves, smaller part of its energy and shorter mean wave period as well as more significant roller energy.

scholarly journals The draft genome of the specialist flea beetle Altica viridicyanea (Coleoptera: Chrysomelidae)

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Huai-Jun Xue ◽  
Yi-Wei Niu ◽  
Kari A. Segraves ◽  
Rui-E Nie ◽  
Ya-Jing Hao ◽  
...  
Keyword(s):  
Host Plant ◽  
Plant Cell Wall ◽  
Flea Beetle ◽  
Repetitive Sequences ◽  
Draft Genome ◽  
Gene Families ◽  
Ecological Speciation ◽  
Secondary Chemistry ◽  
Host Plant Specialization ◽  
Insight Into

Abstract Background Altica (Coleoptera: Chrysomelidae) is a highly diverse and taxonomically challenging flea beetle genus that has been used to address questions related to host plant specialization, reproductive isolation, and ecological speciation. To further evolutionary studies in this interesting group, here we present a draft genome of a representative specialist, Altica viridicyanea, the first Alticinae genome reported thus far. Results The genome is 864.8 Mb and consists of 4490 scaffolds with a N50 size of 557 kb, which covered 98.6% complete and 0.4% partial insect Benchmarking Universal Single-Copy Orthologs. Repetitive sequences accounted for 62.9% of the assembly, and a total of 17,730 protein-coding gene models and 2462 non-coding RNA models were predicted. To provide insight into host plant specialization of this monophagous species, we examined the key gene families involved in chemosensation, detoxification of plant secondary chemistry, and plant cell wall-degradation. Conclusions The genome assembled in this work provides an important resource for further studies on host plant adaptation and functionally affiliated genes. Moreover, this work also opens the way for comparative genomics studies among closely related Altica species, which may provide insight into the molecular evolutionary processes that occur during ecological speciation.

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