In recent times, communities and structures along the Gulf of Mexico have experienced the destructive and devastating impact of hurricane surges and waves. While the impacts of surges have been studied, there exists a need for (1) the understanding of open-coast and bay environment hurricane wave conditions and (2) expedient prediction, for rapid evaluation, of wave hazards as a function of hurricane parameters. This thesis presents the coupled ADCIRC-SWAN numerical model results of wave height sensitivity based on the investigation of several hurricane parameters. Also presented is the development of parameterized maximum significant wave height models. These are determined by incorporating three forms of an equivalent fetch into (1) dimensionless best-fit equations and (2) Shoreline Protection Manual (SPM) method. Computational results indicate that for a range of simulated hurricane parameters, a wide range of spatial and temporal characteristics, for the significant wave height, exists. The location of hurricane landfall results in a significant difference in the wave height at specified points. Additionally, the variation in central pressures, radius sizes and forward speeds leads to elevated surge levels that contribute to wave generation. Furthermore, the time evolution trend of the generation of the significant wave height is found to be unique to its geographic location. In the development of parameterized maximum significant wave height models, the dimensionless best-fit equation approach indicates how strongly the various forms of the equivalent fetch and the bathymetric depth ultimately determines the predicted maximum significant wave height. This approach yielded RMSE that range between 0.52m – 0.68m. Additionally, the accuracy for this approach varied greatly as the highest scatter index was 0.28 for the open-coast points and 0.37 for the bay points. The SPM approach gives an indication of how strongly the functional form of the equivalent fetch determines the predicted maximum significant wave height. When compared to the dimensionless approach, this method produced a lower RMSE of 0.37m and a greater accuracy for the scatter index of 0.23 for the open-coast points and 0.31 for the bay points.

¡@The ocean ambient noise of coast is mainly influenced by sea waves, boats or ships, or human¡¦s coast activities. Among them, most of the ambient noise is from the breaking wave noise caused by wind, and its frequency range is quite wide (0.5~50 kHz). The breaking wave noise mechanism of surf zone is very complex, and has a variety of signal features. In this research, the location is at the Sizih Bay near Kaohsiung Harbor. Hydrophone was used to collect the noise and the wave motion process of surf zone was recorded simultaneously with a digital video camera. It was shown from the experiment results, as the wave evolved in the surf zone, it would eventually become unstable and collapsed, so a large amount of air would be trapped in water and forming bubble clouds. The oscillating bubble cloud from breaking wave would generate high frequency sound. The results also indicated that when breaking wave reached the location hydrophone, a wide band pulse sound was generated with a level as high as 120 dB. In the analysis of each frequency (1k, 2k, 3k, 4k, 5k Hz), due to the oscillating effects air bubbles after breaking wave, the noise level at 2~5k Hz were higher as compared to that without breaking wave passing the hydrophone. The last result was also validated by the time integral of the noise energy through out the wave evolution. In addition to the process of breaking waves and residual air bubbles under breaking waves contributing to the breaking wave source, for example discussed in the study breaking wave¡¦s period and breaking wave height, the results from these two studies found, when the longer the breaking wave period , the breaking wave SPL will be bigger with the longer the breaking wave period. And in the breaking wave height, when the breaking wave height much higher, breaking wave SPL will be much bigger too. And learned from these two conclusions , breaking wave periods and height will make the breaking waves source level caused by changes.

Thesis (PhD (Civil Engineering))--University of Stellenbosch, 1989. / ENGLISH ABSTRACT: Several aspects related to the estimation and selection of design wave conditions were investigated. An analysis program which includes strict quality control routines was developed for digital Waverider data. All available Waverider data from deepsea records were analysed with this program. A remarkable similarity in simultaneously recorded wave heights between Cape Town and Port Elizabeth was found. This similarity was used to compile a near continuous wave record over an eight year period for the Southern Cape coast. The 10537 values of significant wave height (Hmo) which made up the record for the Southern Cape were found to give a good visual fit to the Extreme I and Log-normal distributions over the entire range of Hmo values. Design wave heights derived from the Extreme I distribution were found to be insensitive to assumptions regarding the independence and identical distribution of the wave height samples and the method used for parameter estimation. Design wave heights for the coastline between Oranjemund and Port Elizabeth were found to be strongly correlated to the latitude of the recording site. High waves along these coasts are invariably caused by the passage of cold fronts past the southern tip of the continent. Wave heights reduce as the distance from the west to east route of these cold fronts increase, thus the reason for the abovementioned correlation. No deepwater wave records are available east of Port Elizabeth. Shallow water records indicate that a reduction in wave height can be expected between Port Elizabeth and East London.

Ocean wind waves represent the atmosphere-ocean boundary, playing a central role in the air-sea exchanging processes. Heat, mass and momentum are transferred across this boundary, with waves mediating the exchange of principally the momentum between the winds and the ocean surface. During the generation process waves are called wind sea. When they leave their generation area or outrun their generating wind they are called swell. The wave field can be said to be dominated either by wind sea or swell. Depending on the wave regime the momentum and energy exchanging processes and the degree of coupling between the waves and the wind is different. During the growing process, waves act as a drag on the surface wind and the momentum flux is directed downward. When swell dominates the wave field a reverse momentum flux mechanism occurs triggered by swell waves traveling considerably faster than the surface winds. The momentum transfer is now directed from the waves to the atmosphere, and takes place because swell waves perform work on the atmosphere as part of their attenuation process. This upward momentum transfer has an impact on the lower atmosphere dynamics, and on the overall turbulence structure of the boundary layer. A detailed qualitative climatology of the global wind sea and swell fields from wave reanalysis data, is presented, revealing a very strong swell dominance of the World Ocean. The areas of larger potential impact of swell on the atmosphere, from a climatological point of view, are also studied. A model that reproduces the swell impact on the lower atmosphere dynamics, conceptually based on the energy transfer from the waves to the atmosphere, is presented – a  new parameterization for the wave-induced stress is also proposed. The model results are compared with field observations. A modeling simulation, using a coupled wave-atmosphere model system, is used to study the impact of swell in a regional climate model, by using different formulations on how to introduce the wave state effect in the modeling system. / Gränsen mellan hav och atmosfär beskrivs av vågor, dessa spelar en central roll i utbytesprocesser mellan hav och atmosfär. Värme, massa och rörelsemängd överförs vid ytan och utbytet av rörelsemängd mellan vind och havsyta styrs i stor utsträckning av vågorna. Då vågor skapas kallas de för vinddrivna vågor. När vågorna sedan lämnar området där de genererats eller rör sig fortare än den vind som genererat dem kallas de dyning. Ett vågfält kan sägas vara dominerat av antingen vinddrivna vågor eller dyningsvågor. Beroende på vilken vågregim som råder så är kopplingen mellan vågor och vind olika och därmed också utbytesprocesserna för rörelsemängd och energi. Då vågorna genereras fungerar de som en bromsande kraft för vinden och impulsutbytet är nedåtriktat. När dyning dominerar vågfältet inträffar en mekanism för omvänt impulsutbyte som sätts igång av dyningsvågor som färdas avsevärt snabbare än vinden. Rörelsemängd överförs då från vågorna till atmosfären, eftersom dyningsvågorna utför arbete på atmosfären då de dämpas. Den uppåtriktade transporten av rörelsemängd har en stor effekt på dynamiken och turbulensstrukturen i lägre delen av atmosfären. En detaljerad kvalitativ klimatologi av globala vågfält (vinddrivna och dyning) från återanalysdata presenteras och visar att dyning dominerar vågfältet på världshaven. Områden där man kan förvänta sig störst effekt av dyning på atmosfären har identifierats. En konceptuellt baserad modell som reproducerar effekten av dyning på dynamiken i lägre delen av atmosfären presenteras. Modellen styrs av överföring av energi från vågor till atmosfären. I modellen föreslås även en ny parameterisering för våginducerad kraft på havsytan. Modellresultaten är utvärderade mot fältmätningar. En regional klimatmodell, med ett kopplat våg-atmosfärssystem, har använts för att studera den långtida effekten av dyning vid klimatsimulering. Olika formuleringar för beskrivningen av vågornas effekt på atmosfären har använts, beroende på om vinddrivna vågor eller dyning dominerar vågfältet.