Comparison of monthly GRACE-FO gravity fields from KBR and different LRI Level-1B data sets

The main observations to recover monthly gravity fields from the GRACE-FO mission are provided by two different and independent instruments, which are the K-band ranging (KBR) instrument and the Laser Ranging Interferometer (LRI). From general perspective, both instruments should measure the same gravitational signals and lead to a similar recovery of monthly gravity fields.

Official Level-1B products for KBR and LRI are provided by the GRACE-FO Science Data System (SDS) and are processed at NASA’s Jet Propulsion Laboratory (JPL). For LRI, alternative Level-1B products are also provided by the Albert-Einstein-Institute (AEI). The German Research Centre for Geosciences (GFZ) processed monthly gravity field solutions using the different Level-1B data sets mentioned before to assess the quality of these solutions and identify possible differences caused by the different Level-1B products. In view of the upcoming reprocessing of an improved GFZ release 7 (RL07) time series, the processing method was already adapted compared to the current GFZ RL06 standards, e.g., by an optimized stochastic modelling of instrument errors for KBR/LRI, GPS and accelerometer observations.

In this presentation, comparisons between GFZ RL06 KBR solutions and improved GFZ preliminary RL07 KBR and LRI (using different LRI data sets) solutions are made in the spatial and frequency domain, and conclusions are driven in terms of quality and quantity.