Comparisons of Temporal Resolution of Atmospheric De-aliasing Products for the Analysis of Gravity Field Estimation

Despite the increasing accuracies of GRACE/GRACE-FO gravity field models through worldwide endeavors, the temporal aliasing effect caused by the imperfect background models used in gravity field modelling is still a crucial factor that degrades the quality of gravity field solutions. Recognizing the significant impact of temporal resolution in atmospheric de-aliasing models, this study specifically explores its influence on gravity field modeling across frequency, spectral, and spatial domains. Analysis indicates that elevating the temporal resolution from 3 hours to 1 hour has a negligible impact on gravity solutions in both frequency and spectral domains, and this effect is smaller than the variations caused by employing different atmospheric datasets. Nevertheless, in the spatial domain, increasing temporal resolution proves effective in mitigating LRI range-rate residuals, particularly in specific regions of the Southern Hemisphere at mid- and high-latitudes. Mass changes, expressed in Equivalent Water Height (EWH) and derived through P₄M₆ filtering, reveal that the maximum RMS value of spatial differences resulting from enhanced temporal resolution in atmospheric de-aliasing models can reach ~13.4mm in the sub-region of the Congo River Basin. However, using different atmospheric datasets can lead to a maximum difference of ~16.5mm. For the Amazon River Basin, the corresponding maximum discrepancy is ~18.1mm, and that caused by improving temporal resolution is ~9.4mm. Subsequently, the Congo River Basin is divided into several sub-regions using a lat-lon regular grid with a spatial resolution of 3 degrees. The subsequent time series results of mass changes reveal that the maximum contribution of temporal resolution and changes in the atmospheric datasets can reach 11.09% and 21.24%, respectively. These findings underscore the importance of accounting for temporal resolution in de-aliasing products when investigating mass changes at a regional scale.