碩士 / 國立中央大學 / 地球物理研究所 / 98 / On the basis of conservation of angular momentum, the rotational rate of the earth varies with surface and inner earth’s mass fluid and redistribution. Some geophysical phenomena which change earth’s rotational speed will be discovered by analyzing the variation in length of day (ΔLOD). In this study, nearly 50 years ΔLOD data provided from National Centers for Environmental Prediction (NCEP) are used to calculate more accurate estimates and to observe annual signals. This work has two parts. The first part is to calculate zonal response coefficient (κ) for long-period tides relative to the elastic earth and compare with the result of previous studies. The result κ of this study is larger, between 0.315-0.34, and has smaller standard deviation. It means the ocean impacts the elastic earth greater than ocean models at present days. The second part is revealing signals of different periods with wavelet spectral analysis. It shows that the period of El Nino-Southern Oscillation (ENSO) is very regular. It implies that ENSO may have some association with other natural phenomena, which affect their strength sometimes. In addition, this work finds a new geophysics signal which has a period about 13 to 16 years, and more research is necessary to prove that.
| Identifer | oai:union.ndltd.org:TW/098NCU05134013 |
| Date | January 2010 |
| Creators | Chih-Wei Chou, 鄒致瑋 |
| Contributors | Benjamin Fong Chao, 趙丰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 39 |
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