Abstract
Gravity geologic method is one of the important to derive seafloor topography by using altimetry-gravity, and its committed step is gridding of regional gravity anomaly. Hence, we proposed a topography constraint factor weight optimization (TCFWO) method based on ordinary kriging method. This method fully considers the influence of topography factors on the construction of regional gravity grid besides horizontal distance. The results of regional gravity anomaly models constructed in the Markus-Wake seamount area show that the TCFWO method is better than ordinary kriging method. Then, the above two regional gravity models were applied to invert the seafloor topography. The accuracy of derived topographic models was evaluated by using the shipborne depth data and existing seafloor topography models, including ETOPO1 and V19.1 model. The experimental results show that the accuracy of ST_TCFWO (seafloor topography model inverted by TCFWO method) is better than ST_KR (seafloor topography model inverted by kriging method) and ETOPO1 model. Compared with the ST_KR, the accuracy of the ST_TCFWO has improved about 26%. In addition, the accuracy of seafloor topography is affected by the variation of depth, the distribution of control points and the type of terrain. In different depth layers, the ST_TCFWO has better advantages than ST_KR. In the sparse shipborne measurements area, the accuracy of ST_TCFWO is better than that of V19.1, ETOPO1 and ST_KR. Moreover, compared to other models, ST_TCFWO performs better in flat submarine plain or rugged seamount area.
Highlights
The oceans account for about 71% of the world’s total area and are rich in natural resources
The satellite altimetry can quickly derive global marine gravity information [2], and the topography can be constructed based on the correlation between seafloor topography and gravity information [3]
The free air gravity anomaly, ∆g f ( x, y), obtained by satellite altimetry, which is assumed to divided into two parts regional and residual anomaly according to the shipborne depth measurements in geologic method (GGM) [38]:
Summary
The oceans account for about 71% of the world’s total area and are rich in natural resources. Used a three-dimensional rectangular model to replace horizontal thin plate model to construct short wavelength gravity anomaly, and integrated prior terrain information by regularization method to improve the accuracy of seafloor topography inversion. According to GGM principle, grid processing of discrete regional gravity anomaly data is crucial for seafloor topography inversion. Due to the limitation of shipborne sounding technology, the distribution of depth control points is relatively sparse especially in the Southern Ocean [14], which has a great impact on the grid construction of regional gravity anomaly model. The GGM assumes that the residual gravity anomaly has an approximate linear correlation with the seafloor topography, the non-linear influence is ignored [37] This leads to the existence of some topographic information in the regional gravity anomalies. We used the TCFWO method to carry out relevant experiments on Marcus-Wake seamount area to verify the effectiveness and practicability of the method
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