Document Details
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Document Type |
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Thesis |
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Document Title |
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Numerical modelling study of wind wave variability in the Red Sea دراسة تغيرات امواج الرياح في البحر الاحمر باستخدام النمذجة العددية |
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Subject |
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Faculty of Marine Sciences |
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Document Language |
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Arabic |
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Abstract |
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Wind waves are the most dominant forcing parameter that influences the nearshore processes directly. An accurate picture of typical and extreme wave properties is necessary (in both spatial and temporal scale) for a wide variety of research topics and engineering applications. The understanding physics of wind-driven waves and wind-wave coupling is extremely important both for fundamental science and numerous practical applications. Therefore, experimental efforts are targeted at getting reliable information on wind waves in a wide range of spatiotemporal scales: from campaign measurements in areas of special interest to global monitoring wind-seas using sophisticated satellite methods. Basically, the wind and wave climate are assessed based on the data obtained through: in situ measurements, voluntary observing ships (VOS) data, satellite altimeter and model data sets. In the past, the source of wave information was mainly from ship observations. Each source has its own limitation. In situ wave data coverage in the world ocean is sparse and is not become available for longer duration for most of the regions because of its practical difficulty in acquiring the data as well as the cost. The satellite era could produce good spatial coverage for long term but the temporal coverage at a specific location is still under question. Numerical models are the densest source, both in space and time. But the accuracy and resolution will influence the results. The solution for this problem will overcome by combining all the sources, complementing their various drawbacks from the alternative sources.
The waves in the Red Sea have unique characteristics unlike the other seas in the world. Wind waves and climate variability studies in the Red Sea are underdeveloped. Even though the Red Sea is relatively small, the local wind and wave climate needs to be assessed to understand the regional variability and its dependence with the global climate patterns. In this context, a detailed study of wind wave climate and their variability using numerical modeling at the Red Sea has been carried out. Much attention has been devoted to the study of ocean wave climate and its recent variability. This research is carried out of both temporal and spatial scales of the Red Sea covering 32- year period from 1979 to 2010.
Understanding the dynamics of the coastal areas as well as to identify the most important and relevant issues related to the sustainable development of coastal environment requires better knowledge about coastal wave properties. In this perspective, as a second step of the thesis, special attention has given to the process related to the most fragile and dynamic area of the ocean, shallow water waves and its interaction. Accurate knowledge of the near-shore spectrum, its spatial variations and implications to other process are also not studied and known in the Red Sea.
Primary objectives include:
i) To develop a climatology data base through numerical modelling of wind waves in Red Sea and to assess its trends and variability with climate pattern.
ii) To study the interaction multi directional wind waves in the Red Sea
iii) To study the shallow water wave spectral characteristics
Chapter1 deals with the general introduction of the wind-waves, its evolution, history and background together with the regional and global wind wave studies.
Chapter2 describes the data and methodology followed in the research. Various sources of data have been used in the study. The wave buoy data at the central Red Sea spanning 2 years from 2008-2010 along with summer months measurements of directional and non-directional wave data covering few stations at the nearshore regions of the Red Sea were used. Apart from that, the source of input for the numerical model and for validation purpose data from various sources were collected this includes, ASCAT, ECMWF, CFSR and RADS altimeter data and multi-mission satellite products of IFREMER’s Globwave project etc. The details of the wave analysis also explained in this section.
Chapter3 describes the study domain, model used in the study (WaveWatch III and SWAN) and its setup and implementation together with detailed validation of the input sources as well as the output parameters.
Chapter 4 detailed the assessment of the wind-wave variability in the Red Sea over a period of 32 years (1979–2010) by hindcasting the wind-waves using a third-generation spectral wave model, WaveWatch III, forced with the Climate Forecast System Reanalysis (CFSR) winds. The wave model results have been validated against the satellite observations and available measurements in the Red Sea. Study reveals strong spatial and temporal variability of wind speed with a significant wave height in the Red Sea. The role of climatic indices on the wind-wave variability has been assessed. Contrasting trends of the significant wave heights such as negative trends in the northern Red Sea during summer and positive trends in the southern Red Sea during winter are the highlights, where the trends are significant and comparable with the trends at few marginal seas around the globe. A clear distinction exists between the two parts of the Red Sea in response of the variability due to climatic indices. Among the climatic indices, the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation (ENSO) show significant positive and negative correlations with the characteristic wave heights in the northern and southern Red Sea. As a practical application perspective section detailed analysis of wave energy assessment along the coast of Red Sea has been investigated.
Chapter 5 deals with the nearshore wind wave characteristics of the Red Sea as case study. Diurnal variability of wind waves in the central Red Sea has been carried out with both measurement and using model. Role of local and regional winds in superimposition of waves have been studies. The prominent zones of different wave systems in the Red Sea has been identified. Monthly and spatial variability of the superimposed and non-superimposed have been discussed.
Chapter 6 deals with the shallow water spectral characteristics and nearshore wave transformation of wind waves at the Jeddah coast. This study illustrates the nature of wave transformation that can occur along the study area. Results are discussed in detail.
Chapter 7 Summary and conclusions that covers the entire summary of work and the main conclusions of the present study. Scope is provided for future work. |
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Supervisor |
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Prof. Alaa Al-Barakati |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1440 AH
2018 AD |
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Added Date |
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Monday, December 10, 2018 |
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Researchers
| شناس بوتوفيتل رزاق | Razak, Shanas Puthuveetil | Researcher | Doctorate | |
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