Benefit of MAGIC and multipair quantum satellite gravity missions in Earth science applications

SUMMARY We evaluate simulations for single-, double- and multiple-pair satellite gravimetry missions with respect to applications in hydrology, sea level budgeting and solid Earth science. We begin with the retrieval of weekly spherical harmonic solutions from GRACE-FO and MAGIC-like intersatellite laser tracking in the presence of realistic aliasing, as well as from more distant scenarios that would involve flying quantum accelerometers on satellite pairs in various orbital planes of different inclination. To account for realistic applications, we simulate the impact of such data products in basin-averaged total water storage recovery, in the retrieval of water storages via assimilation into global and regional models, in global and regional ocean mass estimation also in combination with radar altimetry and in the monitoring of Earthquakes and submarine volcano growth. While we find that the MAGIC simulation provides the largest improvement step with respect to our GRACE-FO simulation, the more advanced scenarios add sensitivity in particular in applications where gravity and mass change data can be directly equated to observable phenomena. It is more challenging to judge the benefit of advanced missions with scientific applications that involve combination with model ensembles and additional remote sensing data, as their uncertainties may determine the noise floor and will need to be projected into the future, which we did not attempt at here.