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Wave height
About: Wave height is a research topic. Over the lifetime, 5920 publications have been published within this topic receiving 100257 citations.
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TL;DR: In this paper, the effect of structural dynamics on the response of an offshore wind turbine (OWT) supported by a jacket and subjected to wave loads is studied. But the results demonstrate that dynamic effects may amplify the structural response significantly for loading caused by smaller waves, but the amplification is minimal for loading causing by large waves, which have longer periods and, for the jacket geometry considered here, cause large wave-in-deck forces.
41 citations
TL;DR: In this article, physical processes and biological data were collected and analyzed for eight sand resource areas on the New Jersey Outer Continental Shelf to address environmental concerns raised by the potential for mining sand for beach replenishment.
Abstract: Physical processes and biological data were collected and analyzed for eight sand resource areas on the New Jersey Outer Continental Shelf to address environmental concerns raised by the potential for mining sand for beach replenishment. Nearshore wave and sediment transport patterns were modeled for existing and post-dredging conditions, with borrow site sand volumes ranging from 2.1 to 8.8 × 106 m3. Wave transformation modeling indicated that minor changes will occur to wave fields under dominant directional conditions and selected sand extraction scenarios. Localized seafloor changes at borrow sites are expected to result in negligible impacts to the prevailing wave climate at the coast. At potential impact areas along the New Jersey coast, wave height changes averaged approximately ±3 to 15% when compared with wave heights for existing conditions. For all selected sand borrow sites offshore New Jersey, average variation in annual littoral transport was approximately 10% of existing values. Be...
41 citations
TL;DR: In this paper, a large database of deep water wave buoy measurements over a 24-year period is created for four regions comprising the West Coast of the United States, and the regional monthly mean significant wave height (MMSWH) is selected as the defining wave climate parameter and averaging multiple data sources within a region is found to significantly reduce data gaps.
Abstract: SEYMOUR, R.J., 2011. Evidence for changes to the northeast Pacific wave climate. Journal of Coastal Research, 27(1), 194–201. West Palm Beach (Florida), ISSN 0749-0208. A large database of deep water wave buoy measurements over a 24-year period is created for four regions comprising the West Coast of the United States. The regional monthly mean significant wave height (MMSWH) is selected as the defining wave climate parameter and averaging multiple data sources within a region is found to significantly reduce data gaps. Two 12-year periods are compared, showing significant temporal variability but high correlation between regions, allowing the further collapse of the data to a northern and a southern region. Correlations between MMSWH records with three global-scale climate indices are investigated and only the North Pacific Index (NPI), a measure of atmospheric pressure in the Gulf of Alaska, shows strong correlation. The Multivariate ENSO Index (MEI) is less correlated and the Pacific Decadal Index (PDO), which is a measure of ocean surface temperature, provides no significant correlation. A method for displaying multiple correlations is developed that shows the mean of all MMSWH records that occur at unique temporal combinations of two climate indices. The graphics depicting the mean wave height as a function of NPI and MEI for the two 12-year periods are shown to be very instructive in establishing why the two periods are so different. On the contrary, the same procedure with PDO substituted for MEI produces uniform distributions with little interpretive value. Century-scale variation in the climate indices is investigated, and significant linear trends are found for NPI and MEI, both consistent with causing increases in mean wave energy in these regions. Causal relationships for the observed correlations are discussed, and conclusions are reached indicating that global warming is a likely contributor to observed increases in wave intensity in the North Pacific.
41 citations
TL;DR: In this paper, a method to improve shipboard wave height measurement through fusion of wave radar data with measured ship motion response data is presented. But, the results of a recent demonstration of the approach during a sea trial conducted on CFAV Quest in November/December 2008.
Abstract: Defence Research and Development Canada (DRDC) Atlantic has conducted many dedicated seakeeping and structural load trials on the Canadian Navy research ship CFA V Quest and on several Canadian Navy warships. Typically, wave buoys have been deployed to measure seaway wave characteristics; however, there has been an ongoing interest in evaluating shipboard wave measurement systems. These systems have some advantages over wave buoys for short-term trials and are needed for longer-term sea trials and to provide wave input data for tactical and real-time ship operator guidance systems. This paper presents some of our experiences with wave radar. In the last few years there have been significant advances in wave radar technology (systems that extract wave data from backscatter information contained in the video output of X-band navigational radar displays). Commercial "off-the-shelf" systems are now available. While there is evidence that these systems can provide reliable wave data from shore-based or stationary platform installations, it is DRDC's experience on a ship moving in waves, that wave radars can give good direction and frequency measurements but less reliable wave heights. DRDC has developed a method to improve shipboard wave height measurement through fusion of wave radar data with measured ship motion response data. This paper discusses the development of the wave data fusion process, validated through previous sea trial data, and presents the results of a recent demonstration of the approach during a sea trial conducted on CFAV Quest in November/December 2008.
41 citations
TL;DR: In this paper, the authors used high-frequency in situ measurements of water depths and near-bed velocities to estimate bed shear stress on an open intertidal flat in the Yangtze Delta, China.
Abstract: Accurate estimations for the bed shear stress are essential to predict the erosion and deposition processes in estuaries and coasts. This study used high-frequency in situ measurements of water depths and near-bed velocities to estimate bed shear stress on an open intertidal flat in the Yangtze Delta, China. To determine the current-induced bed shear stress (τc) the in situ near-bed velocities were first decomposed from the turbulent velocity into separate wave orbital velocities using two approaches: a moving average (MA) and energy spectrum analysis (ESA). τc was then calculated and evaluated using the log-profile (LP), turbulent kinetic energy (TKE), modified TKE (TKEw), Reynolds stress (RS), and inertial dissipation (ID) methods. Wave-induced bed shear stress (τw) was estimated using classic linear wave theory. The total bed shear stress (τcw) was determined based on the Grant–Madsen wave–current interaction model (WCI). The results demonstrate that when the ratio of significant wave height to water depth (Hs/h) is greater than 0.25, τcw is significantly overestimated because the vertical velocity fluctuations are contaminated by the surface waves generated by high winds. In addition, wind enhances the total bed shear stress as a result of the increases in both τw and τc generated by the greater wave height and reinforcing of vertical turbulence, respectively. From a comparison of these various methods, the TKEw method associated with ESA decomposition was found to be the best approach because: (1) this method generates the highest mean index of agreement; (2) it uses vertical velocities that are less affected by Doppler noise; and (3) it is less sensitive to the near-bed stratification structure and uncertainty in bed location and roughness.
41 citations