| Summary: | 碩士 === 國立中正大學 === 應用地球物理研究所 === 103 === Due to the combined influence of the global warming caused by the increasing greenhouse effect and accelerated melting of glaciers and polar ice, the global mean sea level rise and the related issues have become a great concern to the governments and scientific communities worldwide. In the recent years, satellite altimetry has evolved into one of the tools to monitor global sea level and its change. It is commonly known that the global sea level rise of recent years is in the level of 1–2 mm/year. In order to monitor this small change, the bias and the drift that exists in the current satellite altimetry sea surface height (ssh) measurements are required to be accurately calibrated. Such effort is called satellite altimeter calibration/validation (cal/val). However, the cal/val is a global effort and requires an international cooperation since the there's local sea state difference everywhere. At this point, cal/val has been working in the United States, the European Union, Australia and Taiwan and other areas. The calibration results can be used to correct the altimeter data, to improve the reliability of the global ssh observations, and ultimately, contribute to an accurate monitoring of global sea surface rise. We used GPS buoys, a GPS ship, and a tide gauge near JiangJiung in Tainan, southwest Taiwan and established an absolute calibration mechanism in order to obtain cal/val result in the southeast Taiwan Strait. An innovated method is employed in this study to estimate the height of the GPS antenna on the ship, considering the fuel consumption. We calibrated Envisat ssh measurements at Pass No. 537 with the data between 2002 and October 2010. The absolute bias is 75.27 ± 3.56 cm and the drift is 1.54 ± 6.44 cm/yr. This calibration mechanism is anticipated to be valid to a later altimetry mission: the SARAL/AltiKa.
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