The study is based upon the Vertical Line Array (VLA) of the Asian Seas International Acoustic Experiment (ASIAEX), dated from May 3, 2001 to May 16, 2001, in which the ambient noise was measured and the six frequencies (including 50, 100, 200, 400, 800, 1,200 Hz) were analyzed. The depth dependence of ambient noise levels in shallow water is not significant, and the fluctuations of ambient noise levels can be measured by Fourier analysis. With the similar analysis on static water pressure and temperature variation, the acoustic data has shown obvious in K1 and M2 tidal periods. The frequency dependence of ambient noise was also investigated, the lower frequency components, 50, 100, and 200 Hz, were mainly contributed from distant shipping noise, and the local wind was the dominating factor in higher frequencies such as 400, 800, and 1,200 Hz. This result was further verified by the increased levels at higher frequency due to the typhoon Cimaron during the experiment. Finally, the probability distribution function of ambient noise levels was calculated at each frequency, and was found the lower frequency ambient noise levels were not significantly affected by the typhoon as higher frequency. The threshold frequency of the ambient noise levels affected by the wind wave is about 400 Hz.

Thesis (M.S.)--United States Naval Postgraduate School, 1966. / Includes bibliographical references (leaf 36).

Thesis (M.S.)--Naval Postgraduate School, 1985. / Cover title. "September 1985." Includes bibliographical references (p. 104-108).

Thesis (M.S. in Meteorology and M.S. in Physical Oceanography)--Naval Postgraduate School, March 2005. / Thesis Advisor(s): Wendell A. Nuss, Thomas H.C. Herbers. Also available online.

Made available in DSpace on 2014-12-02T11:16:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-06Bitstream added on 2014-12-02T11:20:51Z : No. of bitstreams: 1 000800446.pdf: 8670525 bytes, checksum: 687615a21e916a82d7d2f71234ea717d (MD5) / Esta pesquisa trata do monitoramento e da previsão da geração de agitação pela ação do vento e da propagação de estados de agitação em dois locais: Porto da Praia da Vitória – Açores – Portugal e Lago da Barragem de Ilha Solteira – São Paulo – Brasil. A metodologia abordada utiliza o modelo numérico SWAN (Simulating WAves Nearshore) que é capaz de simular a geração, propagação e dissipação da agitação marítima, com base na equação para a conservação da ação de onda. Na propagação da agitação marítima, em zonas costeiras abertas ou confinadas, o modelo simula os processos físicos de refração, difração e empolamento devido a variações do fundo e presença de correntes. Também integra na simulação o crescimento de onda por ação dos ventos, a arrebentação por influência do fundo e por excesso de declividade (whitecapping), a dissipação de energia por causa de fricção do fundo, o bloqueio e reflexão por correntes opostas, e a transmissão através de obstáculos. Entre os vários resultados obtidos através do SWAN, destacam-se a altura significativa, os períodos de pico e médio, as direções de pico e média, a dispersão direcional, o parâmetro de largura de banda e nível de água em qualquer parte do domínio computacional. Duas aplicações do modelo SWAN são tratadas nesta tese para a simulação da geração e da propagação de ondas em dois locais distintos: um correspondente a uma zona costeira aberta – a zona marítima adjacente ao porto da Praia da Vitória, na Ilha Terceira do Arquipélago dos Açores, Portugal; e outro correspondente a uma zona confinada, o lago da barragem de Ilha Solteira, São Paulo, Brasil. Para o Porto da Praia da Vitória, utilizaram-se os resultados das previsões da agitação marítima ao largo da zona em estudo, obtidos com o modelo de previsão de larga escala WAVEWATCH III e os dados de vento do ... / This research deals with the monitoring and the forecasting of wind wave generation and propagation at Praia da Vitória – Azores - Portugal and at the reservoir of Ilha Solteira Dam – São Paulo – Brazil. The SWAN numerical model (Simulating Waves Nearshore) is employed. Such a model is able to simulate the generation, propagation and dissipation of sea waves, based on the equation for wave action conservation. In the sea-wave propagation across both open and confined coastal regions, the model simulates the physical processes of refraction, diffraction and shoaling due to bottom depth variations. It also is capable of simulate the presence of currents, as well as wave growth due to wind, bottom induced wave breaking and whitecapping, energy dissipation due to bottom friction, wave blocking and reflection by currents and wave transmission across obstacles. Among the several results produced by SWAN model, it is worth mentioning significant wave height, mean and peak periods, mean and peak directions, directional spreading, bandwidth parameter and sea level anywhere in the computational domain. Two applications of SWAN model are developed to simulate sea-wave generation and propagation at two distinct locations: one corresponds to an open coast location – the maritime region adjacent to Praia da Vitória port, on Terceira Island, Azores archipelago, Portugal; and the other corresponding to a confined region, the reservoir of Ilha Solteira Dam, São Paulo, Brazil. For Praia da Vitória port, results from offshore sea wave forecasts obtained through the large scale model WAVEWATCH III and wind data from MM5 model were used as forcing data for SWAN model. The numerical results were compared to sea-wave data obtained from a wave buoy deployed 4 km away from the coast at water depth of 90 m (Point 2), during 2009 and 2010 with three-hourly averages. The numerical model SWAN proved itself quite ...

Orientador: Carlos Roberto Minussi / Co-orientador: Geraldo de Freitas Maciel / Banca: Anna Diva Plasencia Lotufo / Banca: Mara Lúcia Martins Lopes / Banca: Tiago Zenker Gireli / Banca: Conceição Juana Espinosa Morais Fortes / Resumo: Esta pesquisa trata do monitoramento e da previsão da geração de agitação pela ação do vento e da propagação de estados de agitação em dois locais: Porto da Praia da Vitória - Açores - Portugal e Lago da Barragem de Ilha Solteira - São Paulo - Brasil. A metodologia abordada utiliza o modelo numérico SWAN (Simulating WAves Nearshore) que é capaz de simular a geração, propagação e dissipação da agitação marítima, com base na equação para a conservação da ação de onda. Na propagação da agitação marítima, em zonas costeiras abertas ou confinadas, o modelo simula os processos físicos de refração, difração e empolamento devido a variações do fundo e presença de correntes. Também integra na simulação o crescimento de onda por ação dos ventos, a arrebentação por influência do fundo e por excesso de declividade (whitecapping), a dissipação de energia por causa de fricção do fundo, o bloqueio e reflexão por correntes opostas, e a transmissão através de obstáculos. Entre os vários resultados obtidos através do SWAN, destacam-se a altura significativa, os períodos de pico e médio, as direções de pico e média, a dispersão direcional, o parâmetro de largura de banda e nível de água em qualquer parte do domínio computacional. Duas aplicações do modelo SWAN são tratadas nesta tese para a simulação da geração e da propagação de ondas em dois locais distintos: um correspondente a uma zona costeira aberta - a zona marítima adjacente ao porto da Praia da Vitória, na Ilha Terceira do Arquipélago dos Açores, Portugal; e outro correspondente a uma zona confinada, o lago da barragem de Ilha Solteira, São Paulo, Brasil. Para o Porto da Praia da Vitória, utilizaram-se os resultados das previsões da agitação marítima ao largo da zona em estudo, obtidos com o modelo de previsão de larga escala WAVEWATCH III e os dados de vento do ... / Abstract: This research deals with the monitoring and the forecasting of wind wave generation and propagation at Praia da Vitória - Azores - Portugal and at the reservoir of Ilha Solteira Dam - São Paulo - Brazil. The SWAN numerical model (Simulating Waves Nearshore) is employed. Such a model is able to simulate the generation, propagation and dissipation of sea waves, based on the equation for wave action conservation. In the sea-wave propagation across both open and confined coastal regions, the model simulates the physical processes of refraction, diffraction and shoaling due to bottom depth variations. It also is capable of simulate the presence of currents, as well as wave growth due to wind, bottom induced wave breaking and whitecapping, energy dissipation due to bottom friction, wave blocking and reflection by currents and wave transmission across obstacles. Among the several results produced by SWAN model, it is worth mentioning significant wave height, mean and peak periods, mean and peak directions, directional spreading, bandwidth parameter and sea level anywhere in the computational domain. Two applications of SWAN model are developed to simulate sea-wave generation and propagation at two distinct locations: one corresponds to an open coast location - the maritime region adjacent to Praia da Vitória port, on Terceira Island, Azores archipelago, Portugal; and the other corresponding to a confined region, the reservoir of Ilha Solteira Dam, São Paulo, Brazil. For Praia da Vitória port, results from offshore sea wave forecasts obtained through the large scale model WAVEWATCH III and wind data from MM5 model were used as forcing data for SWAN model. The numerical results were compared to sea-wave data obtained from a wave buoy deployed 4 km away from the coast at water depth of 90 m (Point 2), during 2009 and 2010 with three-hourly averages. The numerical model SWAN proved itself quite ... / Doutor

Thesis: Sc. D., Massachusetts Institute of Technology, Department of Civil Engineering, 1980 / Bibliography: leaves 173-175. / by David William Ostendorf. / Sc. D. / Sc. D. Massachusetts Institute of Technology, Department of Civil Engineering

Wave energy is a major driver for many coastal processes and influences wetland vegetation and shoreline stability. Coastal conservation and restoration projects often include wave climate estimations in the decision-making process for project design. The current method primarily used to estimate a project area's wave climate is the use of wind-wave models. These models use wind speed, wind direction, bathymetry, and fetch to estimate site-specific wave activity. However, these models neglect boat wake which is an important contributor to wave energy in fetch-limited environments. This study used site-specific wave measurements to compare wind-protected and open sites in Back Bay, Mississippi. Study results demonstrated that some protected sites experienced similar or even higher wave activity when compared to the open sites. These findings indicate that excluding boat activity from wave climate estimations could lead to an under-estimation of site-specific wave activity.

The growth rate function is necessary to determine the energy transfer from wind to waves. Analytically, the growth rate function is determined from the Phillips model, for which the mean velocity profile over water surface is important. The analytical model of Phillips using logarithmic form of the mean velocity profile has not been successful. In the present study, two different mean velocity profile models have been used. One of them, based on a mixing length formulation, is found to be appropriate. This profile is related to the sea state, through two approaches, thus enabling the growth rate function from the analytical model to be linked to the sea state. The growth rate function obtained from the analytical model, using this profile, is found to be comparable to that obtained from empirical relations based on pressure measurements when a correction is made to one of the Phillips coefficients. / M.S.

The Spectral Ocean Wave Model (SOWM) is a numerical wave prediction model which calculates directional wave spectra from input wind fields. As do the majority of wave models, it uses a point spectral growth mechanism, i.e., it applies the energy balance equation in a directionally integrated form. The directionality of its growth is obtained from an assumed spreading function on the wind direction. In this study, the energy balance equation is applied in directional form using directional atmospheric energy source functions. The B function of Miles’ instability mechanism is derived following the analysis of Phillips and it is tuned to the directionally integrated form used in the SOWM. Two infinite ocean wave models are used to compare the behavior of the point and directional growth mechanisms under various wind conditions. The directional form shows more flexibility in responding to directionally varying winds while the point spectral form creates excess energy spread widely over direction when operating in the presence of swell. / Ph. D. / incomplete_metadata