Recovery of Bathymetry over Philippine Sea by Combination of Multi-source Gravity Data

According to the "theoretical admittance" and the "observation admittance" of the actual data,the theoretical value of effective elastic thickness in the study area was 10 km. Combining the gravity anomaliesand vertical gravity gradient anomalies,the admittance function is used to construct the 1'×1' bathymetry model over the Philippine Sea by using the adaptive weighting technique.It is found that the accuracy of the bathymetry model constructed is the highest when the ratio of inversion result of vertical gravity gradient anomalies and inversion result of gravity anomalies is 2:3.At the same time,using multi-source gravity data to predict bathymetry could synthesize the superiority of gravity anomalies and vertical gravity gradient anomalies on the different seafloor topography,and the accuracy is better than bathymetry model that only used gravity anomalies or vertical gravity gradient anomalies.Taking the ship test data as the checking condition,the accuracy of predicting model is slightly lower than that of V18.1 model and improved by 27.17% and 39.02% respectively, compared with the ETOPO1 model and the DTU10 model.Checkpoints which the absolute value of the relative error of the predicting model are in the range of 5% accounted for 94.25% of the total