以多衛星測高資料計算全球海域大地起伏及其應用

Abstract

越來越多高精度的衛星測高觀測量，對決定全球海域大地起伏提供了非常珍貴的資料來源 ；面對如此龐大的資料量，則需採取有效、迅速的方法以便計算全球海域大地起伏。在本 文中，分別採用一維（1D）及二維（2D）快速傅利葉轉換法，應用於Stokes'積分式與 de flection-geoid公式來計算大地起伏；其結果顯示，採用1D FFT方法用於deflection-geo id公式計算全球海域大地起伏其理論精度較佳，在分區計算接邊處，不會有不連續的問題 ，且以程式計算時所佔用的記憶體空間較小，故為本研究所採用之方法。全球海域大地起 伏對於求得海水面地形（SST）扮演著極重要的角色，在本研究中將結合由TOPEX/POSEID ON衛星三年的資料與計算出之全球海域大地起伏，進行海流計算；並在全球選取黑潮、灣 流及本格拉海流三個區域，繪製海流圖；另外，並針對黑潮，求出其路徑主軸，並與在海 上利用GEK海流計所實測的資料繪出的路徑主軸作比較，結果顯示兩者十分相近。 More and more satellite altimeter missions provides data sets for the mapping of the marine geoid. With the largement of data, an efficient method for compu ting the geoid is needed. In this study, we apply one dimension(1D) and two di mension(2D) FFT methods to implement stokes' formula and the deflection-geoid formula. The result shows, using the deflection-geoid formula implemented by 1 D FFT method to compute global marine geoid yields more accurate result than t he 2D FFT and there are no discontinuities in border connection. Additionally, the reduction in computer memory is remarkable, and this method was adopted i n this s tudy.The global marine geoid plays a great role in extracting the sea surface topography. Circulations of the Kuroshio, the Gulf Stream and the Ben guela Current have been determined from the three-year TOPEX/POSEIDON altimete r data and the global marine geoid. The paths of the Kuroshio have been obtain ed from the 3-year T/P data and are consistent with the GEK results.