Predicted seafloor topography of the New Zealand region: A nonlinear least squares inversion of satellite altimetry data
Predicted seafloor topography of the New Zealand region: A nonlinear least squares inversion of satellite altimetry data
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DOI：
10.1029/2000jb900099
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发表时间：
2000-07-10
影响因子：
3.9
通讯作者：
Wright, IC
中科院分区：
文献类型：
--
作者：
Ramillien, G;Wright, IC
我们使用非线性最小二乘反演来获得新西兰地区（146度E-165度W，60度S-25度S）的预测海底地形（以下简称RW 99），结合ERS-1和Geosat大地测量任务的测高数据，以及可用的船载重力和回波探测数据。目前，该模型的岩石圈部分主要适用于沉积薄的洋盆，然而，我们已经尝试，虽然只有部分成功，以弥补区域地壳的变化。海洋岩石圈上部具有与半空间冷却模型相关的弹性行为，并在海底卸载载荷下发生挠曲。利用最小二乘理论，地形解导出为调整系数的测高和现场测量的线性组合。这些系数迭代拟合使用测深和测高导出的重力异常之间的非线性算子假设其误差分布是高斯的。该理论使稀疏的原位数据被包括在反演中，如测深和海洋重力剖面。与Smith和Sandwell [1997]（以下简称SS 97）的全球模式相比，RW 99预测的地形受到三倍以上船载测深数据和船载重力数据的约束。三种策略被用来验证RW 99模型。与SS 97模型的均方根（rms）误差310 m相比，RW 99模型的最终残差在104-250 m范围内。这些分量误差是由于模型参数的不确定性，特别是弹性厚度和起伏密度的不确定性，以及海底地形的复杂性。此外，模型反演目前没有考虑变厚度海洋沉积物的重力贡献。
We use a nonlinear least squares inversion to derive predicted seafloor topography (hereinafter referred to as RW99) for the New Zealand region (146 degrees E-165 degrees W, 60 degrees S-25 degrees S), combining altimetry data from ERS-1 and Geosat Geodetic Missions, as well as available shipborne gravity and echo sounding data. Currently, the lithospheric component of the model is principally applicable to thinly sedimented oceanic basins; however, we have attempted, though with only partial success, to compensate for regional crustal variations. The upper part of the oceanic lithosphere has an elastic behavior related to a half-space cooling model and flexing under seafloor relief load. Using least squares theory, the topographic solution is derived as a linear combination of altimetry and in situ measurements with adjusted coefficients. These coefficients are iteratively fitted using nonlinear operators between bathymetry and altimetry-derived gravity anomalies assuming their error distributions are Gaussian. The theory enables sparse in situ data to be included in the inversion, such as depth soundings and marine gravity profiles. In comparison with the global model of Smith and Sandwell [1997](hereinafter referred to as SS97); the RW99 predicted topography is constrained by over threefold more shipborne soundings data and the inclusion of shipborne gravity data. Three strategies are used to validate the RW99 model. Compared to the root-mean-square (rms) error of 310 m of the SS97 model, final residual differences for the RW99 model are within the range of 104-250 m. These component errors are the result of uncertainties of model parameters, especially the elastic thickness and the relief density, but also the complexity of seafloor topography. In addition, the model inversion does not presently consider gravitational contributions of marine sediments of Variable thickness.