A physically informed spatial filter for destriping GRACE time-variable gravity fields

SUMMARY The Gravity Recovery and Climate Experiment (GRACE) and its Follow-On mission provide essential observations of Earth’s surface mass redistribution. However, inherent north–south striping noise in the GRACE spherical harmonic products limits their application at subbasin scales. To address this, we introduce a novel spatial domain decorrelation filter, the Physical-Informed Spatial Pattern (PISP) filter, which leverages the structured physical characteristics of the noise for its precise identification and removal. Comprehensive numerical experiments validated that PISP effectively eliminates striping noise globally and yields a consistent noise background across latitudes, with noise reduced to a uniform level in more than 90 per cent of the months examined and with stable performance under strong-noise conditions. In a case study of water storage variations in Lake Victoria, PISP preserves the primary signal amplitude and reduces the root-mean-square error relative to reference data to 5.84 cm after spatial smoothing, outperforming the 6.81 cm achieved by the Multivariate Variational Mode Decomposition Spatial filter and DDK6. Furthermore, for three earthquakes with magnitudes exceeding 8.8, PISP effectively removes striping noise using regional masking, successfully recovering the coseismic signal morphology. By further verifying the method’s stability across various noise scenarios, the results demonstrate PISP’s potential for future global research integrating multisatellite gravity data.