Evaluation of the Time Varying Gravity Fields from GRACE Follow-On LRI Instrument

The Laser Ranging Interferometer (LRI) instrument on-board of the GRACE Follow-On (GRACE-FO) satellites has been collecting science data since a June 2018, a few weeks after launch. Though the LRI instrument, based on design concepts developed for a future LISA mission, was intended mostly as a demonstration instrument, it has far-exceeded its mission requirements and has provided intersatellite ranging observations with improved signal-to-noise ratio compared to the K-Band Ranging (KBR) instrument. The exploitation of the LRI observations has led to a set of monthly gravity field solutions comparable in many ways to the ones obtained from KBR. Though the ranging observations from the LRI have a much lower high-frequency noise content, this has not so far led to an improvement of the time-varying gravity estimates in the spatial domain, while stark differences are visible in the spectral domain between the KBR and LRI fields. We present the series of LRI gravity models in comparison to its KBR counterpart, as well as regional intercomparisons of the gravity solutions against hydrology models.