Improved alternative GRACE-FO accelerometer transplant product computed at TU Graz

The GRACE-FO satellites are equipped with three-axis accelerometers, measuring the non-gravitational forces. After one month in orbit, the GRACE-D accelerometer data degraded and its measurements were replaced by synthetic accelerometer data, the so-called transplant data, officially generated by the Jet Propulsion Laboratory (JPL). For the ITSG-Grace2018 GRACE-FO release, the gravity field recovery is based on an alternative in-house transplant product (Behzadpour et. al. 2021,  https://doi.org/10.1029/2020JB021297). This product is generated by a remove-restore method implementing non-gravitational force models.

In this work, we present a new improved version of TU Graz transplant product. The force modelling includes now a tuned satellite macro model, self-shadowing effects, and thermal radiation forces. For the transplant step, an additional estimate of the thermospheric density along the orbit was introduced to account for the different orientation of the satellites.