GRACE/GRACE-FO Monthly Mascon Gravity Field Solutions: Processing Chain and Preliminary Results

Since 2002, GRACE and GRACE-FO have provided pioneering observations of temporal variations in Earth’s gravity field. Mass flux estimation for GRACE/GRACE-FO typically parameterizes as a spherical harmonic series. Alternatively, mass concentration (mascon) solutions divide the Earth's surface into discrete blocks, allowing for the direct estimation of mass anomalies. The mascon approach, which employs locally defined basis functions rather than global ones, facilitates the incorporation of a-priori information to reduce aliasing effects and other modeling errors.

This study presents preliminary results of a newly developed mascon processing chain to retrieve mascon solutions for GRACE/GRACE-FO data. The solutions are derived from least squares inversions with Tikhonov regularization using the open-source software GROOPS. The processing scheme employs the point-mass mascon approach, and explicitly links inter-satellite range rate measurements to an analytical mascon formulation. The resulting mascon solutions are based on globally distributed, equal area blocks approximating 3° resolution at the equator. By incorporating tailored geographic information into the regularization process, the scheme mitigates the noise in the solutions and permits the geophysical signals to be detected. This approach eliminates the need for post-processing filters to remove north-south stripes and achieves a balance between signal recovery magnitude and error reduction.

This contribution displays preliminary results and discusses the processing chain for a point-mass mascon approach while comparing the preliminary mascon solutions with postprocessed spherical harmonic solutions in both spatial and spectral domains.