東海海域海底地形研究：以衛星測高所反演的重力場推估

Abstract

本研究結合數種衛星測高資料反演東海重力場，進而推估研究區域之海深模型。在波形重定方面，採用次波形門檻值演算法並搭配高斯濾波去除雜訊；在反演重力場方面，分別比較了逆 Vening Meinesz 公式 與最小二乘配置法，並分析其精度。在計算海底地形方面，採用重力地質法計算出最終的海深模型，並分析參考場與地質密度差對海深計算的影響。重力成果方面，與船測重力異常檢核後，發現波形重定技術能有效提升約3~6 mgal 的精度；於海深成果方面，用大陸礁層船測海深值評估精度，可發現本研究計算之模型較ETOPO1模型獲得更高之精度，於淺海區域與深海區域精度約比百分之四。

We investigated the bathymetric model over the East China Sea by altimetry-derived gravity. A sub-waveform threshold is used and a Gaussian filter is applied in the retracking processing. Two methods, the Inverse Vening Meinesz (IVM) formula and least square collocation (LSC), are used to derive gravity anomalies from retracked altimeter data. The bathymetric models are constructed by gravity-geological method (GGM) using the altimetry-derived gravity. Different reference models and density contrasts for GGM are taken into account. The use of retracking technique improves the gravity estimation by 3-6 mgal, based on the evaluation with shipborne gravity. The accuracy of the predicted bathymetric model in this study outperforms ETOPO1 DEM model. In shallow sea and abyssal region, the accuracy of the predicted bathymetric model in this study is improved by 4 %.