碩士 / 國立交通大學 / 土木工程系所 / 93 / This research focuses on improvement of Geosat/GM satellite altimeter data by waveform retracking and the experimental area is over Taiwan waters. In comparison to altimeter waveforms over open oceans, waveforms over waters close to land are complicated. This work uses an improved threshold algorithm of waveform retracking to determine gate correction and then to compute range correction and sea surface height (SSH) correction. The performance of retracking is assessed by comparing SSH with geoidal heights from a high resolution geoid model around Taiwan. Over the entire region of comparison, the agreement between retracking-corrected SSH and geoidal heights is improved by 8%. Over waters less than 10 km to the coasts, the improvement is 10% and the number of valid SSH increases. The methods of inverse Vening Meinesz formula and least square collocation are used to compute gravity anomalies from both raw SSH and retracking-corrected SSH. The results show that, in comparison to raw SSH, retracking-corrected SSH yield a better agreement between altimeter-derived gravity anomalies and shipborne gravity anomalies, with a best case of 12% improvement. Least-squares collocation is used to compute gravity anomalies from a combined set of retracking-corrected SSH and airborne gravity data, which agree best with the shipborne gravity anomalies in all cases.
| Identifer | oai:union.ndltd.org:TW/093NCTU5015028 |
| Date | January 2005 |
| Creators | YuTing Liu, 劉祐廷 |
| Contributors | Cheinway Hwang, 黃金維 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 88 |
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