Combined Inversion Theory And Model Development From Multi-source Gravity Data

The implementation of CHAMP,GRACE/GRACE-FO,and GOCE gravity satellites can provide a large amount of observation data for the development of a high-precision and high-resolution earth gravity field model;the wavelength information of gravity field reflected by different gravity field detection data is different.Therefore,making full use of the different spectrum information of satellite gravity data and ground gravity data to carry out the joint inversion of multi-source gravity field detection data,and develop the high-precision and high-resolution static gravity field model is of great significance.This thesis focuses on the combined inversion theory and model development of multi-source gravity field detection data,mainly including the gravity field inversion based on GOCE satellite Level 1b gravity gradient data,and combined inversion with GRACE satellite data and EGM2008 gravity anomaly data.The specific research contents are as follows:(1)The theory and method of gravity field inversion using GOCE satellite gravity gradient data are studied.The detailed calculation method of temporal gravity field variations correction of GOCE satellite gravity gradient data,the gross error detection method of GOCE satellite gravity gradient data,and effective filtering method are given;Calculation software packages have been developed,and the direct method has been used to recover the gravity field from the level 1b gravity gradient observation data of GOCE satellite.(2)In view of the serious ill-posed problem of the normal equation of gravity field inversion by using GOCE gravity gradient observations alone,this thesis studies the method of gravity field inversion from a combination of GOCE satellite and GRACE satellite data at the level of the normal equation,the method of variance component estimation for determining the weight ratio of different observations,and the Kaula regularization constraint method to suppress the ill-conditioned of the normal equation.In addition,the fusion method of gravity anomaly data between the satellite-only observations and the EGM2008 model gravity anomaly data is also studied,which can improve the resolution and accuracy of the satellite-only gravity field model.(3)Based on the above theories and methods,this thesis developed the unconstrained gravity field model Tongji-GOGR2019 S up to 220 degrees/order by using about 2 years of Level 1b gravity gradient data and combining the normal equation of Tongji-Grace02 s,and the 300 degree/order model Tongji-GOGR2021 by using the complete mission data and Kaula regularization constraint.It is shown that the accuracy of the Tongji-GOGR2019 S and the Tongji-GOGR2021 models are comparable to the state-of-art sixth-generation GOCE model of the same order by using the software of EGMTools independently developed.(4)The 360 degree/order Tongji-GMMG22 C model combined from the unconstrained normal equation of Tongji-GOGR2021 and the gravity anomaly normal equation reconstructed from the EGM2008 model.The estimation results show that the accuracy of the Tongji-GMMG22 C model of 360 degree/order is slightly better than that of the EGM2008 model,and which is comparable to the state-of-art such as the XGM2019 model of the same order.