Two-Satellites Tandem Mode Design and Accuracy Analysis of Gravity Field Inversion for Independent Marine Altimetry Satellite

In order to meet the future development requirements of independent altimetry satellite, a two-satellites tandem mode is designed which can cover the whole ocean area with 1'×1' resolution after 2.3 years of flying. Firstly, two gravity field inversion methods for independent marine altimetry satellite are proposed, one of which takes the tandem orbital characteristics into account while the other does not. Secondly, the simulation calculation of random error propagation under normal distribution is carried out by using the inverse Vening-Meinesz method, and the corresponding indices of error under the two approaches are obtained.Based on the above error indexes, the corresponding precision indexes of the two kinds of gravity field inversion methods in the tandem flight mode are calculated respectively.Among, the second inversion method makes full use of the characteristics of the relative orbit determination by using the east-west observations in the tandem mode, and takes account of the systematic error characteristics of the propagation error and geophysical correction error under the close-range conditions. Therefore, the vertical deflection accuracy of the second inversion method is higher than that of the first inversion method, and its gravity field inversion also has certain advantages accordingly.The theoretical calculation results show that using the first inversion method, we can get a gravity anomaly accuracy of 6-10 mGal in 2.3 yearsand 4.2-7.1 mGal in 4.6 years; while using the second inversion method, a gravity anomaly accuracy of 3.9 mGal in 2.3 years and 2.8 mGal in 4.6 years can be obtained, respectively.