An analysis of inter-satellite laser ranging interferometer on GRACE Follow-On satellites for time-variable and high-resolution static gravity fields
Abstract
We present a new method of analysing inter-satellite tracking data such as from GRACE Follow-On K-Band microwave and laser ranging interferometer systems for detecting time-variable and static gravitational variations. The method is based on the residual range-rate data with respect to the reference range-rate computed with dynamic orbital state vectors. Then, we apply a numerical differentiation to compute range-acceleration residuals. We found that the range-acceleration residuals are near-perfectly correlated with the line-of-sight gravity difference (LGD) between two spacecrafts and the transfer (admittance) function between them can be determined regardless of time and space (Ghobadi-Far et al., 2018, JGR-Solid Earth, https://doi.org/10.1029/2018JB016088). The transfer function, to be applied directly to range-acceleration residuals, enables accurate LGD determination with the error of 0.15 nm/s2 over the frequency band higher than 1 mHz (5 cycles-per-revolution), whereas the actual GRACE measurement error is several times larger. This is accurate enough to retrieve time-variable and static gravity signals at the frequency higher than 1 mHz (equivalently, spatial resolution of ~4000 km and smaller). We applied such method to detect instantaneous gravity changes caused by large tsunamis and atmosphere and ocean mass variation at time scale of hours. Moreover, we found that the high-frequency laser tracking data can be used as excellent new datasets to validate the state-of-the-art static gravity field models by distinguishing important differences among the models. We will present the analysis results particularly from new GRACE Follow-On laser ranging interferometer system.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E2132H