基于重力异常迭代延拓的南海海底地形反演

Bathymetry inversion of South China Sea based on iterative continuation of gravity anomalies

通过迭代延拓法对重力异常进行向下延拓,并对导纳法反演的中国南海海底地形进行精度评估。首先,利用HY-2A高度计数据通过最小二乘配置法计算得到重力异常,使用迭代延拓法将重力异常延伸至延拓面;然后,利用重力异常与海底地形的相干性,确定海深反演波段为20~115 km。基于CRUST 1.0全球地壳模型,得到均衡补偿模型参数,海深反演结果表明,均衡补偿导纳海深模型比未补偿导纳海深模型的精度提高约9 m,并且两个反演水深模型略优于ETOPO1水深模型和DTU10水深模型,利用迭代延拓法提升重力异常计算海底地形的精度;最后,给出影响海底地形反演精度的主要因素。

Gravity anomalies were extended downward with iterative continuation method,and the bathymetry of the South China Sea was inverted by admittance theory and the accuracy was evaluated.Firstly,the least squares collocation was used to calculate the gravity anomalies in the South China Sea based on the HY-2A altimeter data,and iterative continuation method was used to extend the gravity anomaly to the continuation surface.Then,the bathymetry inversion wavelength band was determined to be 20-115 km by using the coherence of gravity anomalies and bathymetry.Based on CRUST 1.0 global crust model,the parameters of isostasy compensation admittance model were obtained.The results of bathymetry inversion show that the accuracy of isostasy compensation admittance bathymetry model was improved about 9 m than that of the un-compensation admittance bathymetry model,and that both the models are slightly better than ETOPO1 and DTU10 bathymetry models.The iterative continuation method was used to improve the accuracy of gravity anomaly calculation of seafloor topography.Finally,the main factors affecting the inversion accuracy of seafloor topography were given.