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

For GRACE-FO gravity field recovery synthetic accelerometer data is required to replace the GRACE-D measurements due to their high noise level. Official transplant products published by the Jet Propulsion Laboratory (JPL) are the calibrated acceleration product (ACT) and the updated hybrid accelerometer transplant (ACX). At TU Graz an alternative in-house transplant product is generated using a remove-restore method. Based on the work from Behzadpur, 2021 the transplant product was further optimized. 

Improvements in the force modeling comprise an adjusted satellite macro model and a self-shadowing model as well as the consideration of thermal re-radiation. To account for the different orientations of the satellites in relative pointing mode, an additional step was introduced in the transplant processing by determining the thermospheric density along the orbit. Investigations were carried out to further improve the accelerometer transplant by incorporating data from the GRACE-D accelerometer.