Improving the accuracy of GRACE Earth’s gravitational eld using the combination of di erent inclinations

In this paper, the GRACE Earth’s gravitational eld complete up to degree and order 120 is recovered based on the combination of di erent inclinations using the energy conservation principle. The results show that because di erent inclinations of satellite are sensitive to the geopotential coe cients with di erent degrees l and orders m, the design of GRACE exploiting 89° inclination can e ectively improve the accuracy of geopotential zonal harmonic coe cients. However, it is less sensitive to the geopotential tesseral harmonic coef- cients. Accordingly, the second group of GRACE exploiting lower inclination is required to determine high-accurately the geopotential tesseral harmonic coe cients and cover the shortage of the single group of GRACE exploiting 89o inclination. Two groups of GRACE individually exploiting 89° + (82°–84°) inclinations are the optimal combination of the Earth’s gravitational eld recovery complete up to degree and order 120. In the degree 120, the joint accuracy of cumulative geoid height based on two groups of GRACE individually exploiting 89° and 83° inclinations is averagely two times higher than the accuracy of a group of GRACE exploiting 89° inclination.