| Summary: | 碩士 === 國防大學理工學院 === 空間科學碩士班 === 97 === GPS positioning accuracy taking progress day by day, but it will be influenced by environment factors such as ocean tide loading, solid earth tide and polar tide. The ocean tide loading is more obvious in coastline and the bay areas. Ocean tide loading is affected by the attraction between the earth and the sun. The M2 tide is the biggest effect of ocean tide loading. Therefore, estimation of ocean tide loading needs long period observed data (e.g.: GPS, tide gauge, satellite altimetry data and gravitational data). Then used different methods (hydrodynamics, harmonic analysis, orthotide approach, finite element method and inverse theory) to construct ocean tide loading model.
This study attempts to build ocean tide loading model nearby Taiwan area by using GPS data. Testing areas are from 119.5°E ~122.5°E in longitude and 21.5°N~25.5°N in latitude. There are 183 days’ GPS observed data of 60 fixed stations to be process by Bernese5.0 software. In order to get inland harmonic constant used harmonic analysis (T_Tide) and the constant of ocean region used the EOT08a global ocean tide loading model. The grid of testing area is made by GMT software. The filter of this study used median filter wavelength 250km to obtain the best regional ocean tide loading model (FM250).
The result of this study shows GPS solution promoting approximately 1.63%~55.92%, average promoting approximately 19.85% in height component by using 20 GPS stations observed data with FM250 regional ocean tide loading model developed in this study.
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