New Static Gravity Field Model SWJTU-GOGR01S Derived from GOCE Data and GRACE Normal Equation

Global static gravitational field determined by GOCE and GRACE satellite data has become a hotspot in current research of geodesy. In this paper, a satellite-only global static gravity field model entitled SWJTU-GOGR01S up to degree and order 210 is recovered based on 3 years of GOCE gravity gradient data and ITG-GRACE2010S model's normal equation from 7 years GPS and K-band rang rate data. Four high precision GOCE gradiometer components (V_xx, V_yy, V_zz, V_xz) are filtered by the zero phase finite impulse band-pass digital filter, and then gradient observation equation is founded directly in gradiometer coordinates which avoids the loss of gradiometer component in accuracy in the conversion process. The optimal weight of the combination result of GOCE and GRACE data is determined by variance component estimation and the GOCE data polar gaps is dealt with the Kaula regularization method. Comparing the internal and external precision of SWJTU-GOGR01S with EIGEN-6C2 and GPS leveling data of North America, the results show that the geoid error and cumulative error of the SWJTU-GOGR01S model with degree and order 210 are 1.3 cm and 5.7 cm respectively. Compared with the fourth generation direct approach and time-wise approach models released by ESA, GOCO02S and GOCO03S model, the accuracy of the model SWJTU-GOGR01S is verified basically consistent with the model TIM-R4. The precision of SWJTU-GOGR01S model is also better than GOCO02S and GOCO03S model.