碩士 / 國立臺灣大學 / 海洋研究所 / 101 / The one-year ambient noise recorded by the OBS system deployed off the east coast of Taiwan in the TAIGER (TAiwan Integrated GEodynamics Research) project was employed to calculate the Noise Cross-correlation Functions (NCF) of the noise field. The data recorded between the stations located at Yaeyama Ridge (water depth about 4000 m), starting from May of 2008 for a period of more one year, have been processed using the noise cross correlation technique. The results of NCF have shown that there exists strong microseism energy in the frequency band between 0.1 Hz and 0.4 Hz all year around, and has also demonstrated a large temporal variations as much as 3 seconds. To understand the temporal variations of NCF, we conduct the following analyses: 1. Numerical simulations using OASES: the result suggests that the generalized Green’s function found between stations is the interface wave traveling between the ocean and the elastic seafloor. The propagating speed of the interface wave is mainly dominated by the shear velocity of the seafloor, and is little affected by the ocean sound speeds. 2. Variable frequency content of NCFs: due to wavelength-dependent nature (dispersion) of the interface wave, the travel time will be a function of the frequency. 3. Non-diffusive noise distribution: the travel time obtained from NCF between stations requires that the noise field is diffusive. The directionality of noise distribution will affect the NCFs dramatically. A theoretical formula is adopted to correct the offset of observed travel time by directional noise fields using the wavewatch III model.
| Identifer | oai:union.ndltd.org:TW/101NTU05279021 |
| Date | January 2013 |
| Creators | Shih-Chieh Lin, 林士傑 |
| Contributors | Chen-Fen Huang, 黃千芬 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 81 |
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