Precise Recovery of the Earth's Gravitational Field With GRACE: Intersatellite Range-Rate Interpolation Approach

Abstract

First, a new observation equation of a satellite from the intersatellite range-rate interpolation approach (IRRIA) is created by inserting the precise intersatellite range-rate measurements into the line-of-sight component of the orbital velocity difference vector. Second, by a comparison of the two-point, four-point, six-point, and eight-point interpolation formulas, the accuracy of the Earth's gravitational field is substantially improved using the six-point IRRIA formula due to an optimum signal-to-noise ratio. Third, a new Gravity Recovery and Climate Experiment (GRACE) satellite-only Earth gravity field model WHIGG-GEGM02S is produced by GRACE-Level-1B real data during the year 2009 using the IRRIA, and the cumulative geoid height error and cumulative gravity anomaly error are 1.140 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> m and 1.807 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> m/s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at degree 120, respectively. Finally, the new WHIGG-GEGM02S model is much closer to the existing GGM02S model by a comparison of the root mean square of the geoid height differences between the global positioning system/leveling observations and the existing seven GRACE global gravity field models.