利用GEOSAT及TOPEX/POSEIDON衛星測高儀推求西太平洋海洋環流

Abstract

海洋環流為物理海洋學重要研究課題之一,從衛星測高儀的資料及一已知 的大地水準面,應用大地測量的方法,可以推求出海水面地形 。應用上述 方法欲推求高階海水面地形最大的限制為大地水準面的誤差,在此則以濾 波的方法克服此限制。本論文利用平差後的GEOSAT(1986年12月至1987 年11月)及TOPEX/PO- SEIDON(1992年9月至1993年9月)衛星測高儀的資料, 及OSU91A的大地位模式,並以高斯濾波器作平滑化,推求西太平洋之海洋環 流。應用上述方法,在西太平洋環流部份,可獲得與傳統資料相似的結果, 在黑潮路徑上,與傳統浮球的方法所提供的海流圖類似,在南海部份,則與 中國大陸所作的成果相似。以資料軌道精度而言,若區域不大,TOPE- X/ POSEIDON可達3cm以下,GEOSAT可達15cm以下。 Determination of ocean currents is one of the important problems in physical oceanography. Using geodetic techniques , the SST(sea surface topography) can be determined from altimeter data and geoid undulations. The primary limitation in the determination of the SST for higher harmonic degrees is due to the error of the geoid. A two dimensional filter has so been employed to overcome this difficulty. We used the Gaussian filter to smooth the adjusted GEOSAT (1986/12-1987/11) and TOPEX/POSEIDON(1992/9-1993/9) altimeter data, which together with the geoid model of OSU91A, have beened to determine the ocean circulation over the Western Pacific Ocean. The altimetric results from this study show circulation patterns similar to those obtained from traditional oceanogra- phic method. In particular, those from the drifters results over the Kuroshio Current. Also, the results shoe a well definedrrent system over the South China Sea. The orbital accuracy of GEOSAT data is below 15cm, and is 3cm for TOPEX/POSEIDON, which is similar to that by Nerem and Tapley.