Determination of static gravity field model by using satellite data of GOCE and GRACE

The high-precision static satellite gravity field models have important applications in fields such as global ocean circulation research and global/regional digital elevation datum determination. In this paper, we discussed the determination of high-degree static satellite gravity field models with GOCE observation, GRACE observation and the joint of them. We first constructed a 300 degree Satellite Gravity Gradiometry (SGG) normal equation with the high-precision gravitational gradient components V-xx, V-xy, Vz(z) and V-xz throughout the entire mission of GOCE by the Direct least squares method, and a 130-degree Satellite-to-Satellite Tracking (SST) normal equation with the SST observation data by the point-wise acceleration approach. The 300-degree GOCEonly satellite gravity field model GOSGO2S is determined by combining SGG and SST normal equations with variance component estimation. The 180-degree model SWPU-GRACE2021S is then determined based on the dynamic approach with the GRACE data throughout the entire mission cycle of 15 years, and the normal equation is combined with GOCE normal equation to determine WHU-SWPU-GOGR2022S, a joint model of GOCE and GRACE. Finally, the XGM2019 model and GPS/leveling data are used for precision analysis of GOSGO2S, SWPU-GRACE2021S and WHU-SWPU-GOGR2022S in frequency domain and space domain respectively. The results show that the accuracy of GOSGO2S and WHU-SWPU-GOGR2022S is comparable to GO_CONS_GCF_2_ DIR_R6, GO_CONS_GCF_2_TIM_R6, GO_CONS_GCF_2_SPW_R5, G00006s and Tongji-GMMG2021S that use the entire mission data of GOCE satellite and the accuracy differences are in the order of millimeters. The SWPU-GRACE2021S model has the same accuracy below degree/order 160 as the international mainstream of GRACE satellite gravity field models, i. e., ITSG-Grace2018s and Tongji-Grace02s.