Precise Recovery of the Earth's Gravitational Field by Grace Follow‐On Satellite Gravity Gradiometry Method

Abstract

AbstractBecause the twin GRACE Follow‐On satellites are equivalent to the one‐dimensional horizontal gravity gradiometer with a baseline length of the intersatellite range, the feasibility demonstrations on precisely and rapidly recovering the next‐generation Earth's gravitational field by the GRACE Follow‐On satellite gravity gradiometry method (GFO‐SGGM) are carried out in this study. The research results are as follows: Firstly, based on the GRACE Follow‐On satellite gravity gradiometry method, using the orbital parameters of the satellite (e.g. orbital altitude of 250 km, intersatellite range of 50 km, orbital inclination of 89° and orbital eccentricity of 0.001), the measurement precisions of key payloads (e.g. 10−6 m in intersatellite range, 10−7 m·s−1 in intersatellite range‐ rate and 10−10 m·s−2 in intersatellite range‐acceleration by the interferometric laser ranging system, 10−3 m in orbital position and 10−6 m·s−1 in orbital velocity by the GPS receiver, and 10−11 m·s−2 in non‐conservative force by the accelerometer), a 30‐day observation time and a sampling interval of 10 s, the Earth's gravitational field complete up to degree and order 120 is accurately recovered, and the cumulative geoid height error is 9.331×10−4 m at degree 120. Secondly, in 120 degrees, the accuracy of the gravity recovery from the future twin GRACE Follow‐On satellites is averagely improved by about 61 times than that from the current twin GRACE satellites. Therefore, the GRACE Follow‐On satellite gravity gradiometry method promisingly becomes a preferred approach for further improving the determination accuracy of the next‐generation Earth gravity field model. Finally, the advantages of the next‐generation GRACE Follow‐On mission as compared with the present GRACE mission principally consist of the lower orbital altitude of the satellite between 200 km and 300 km, the higher measurement accuracy of the space‐borne instruments between 10−7 m·s−1 and 10−9 m·s−1 and the shorter intersatellite range between 50 km and 100 km.