TUM GRACE/GRACE-FO Mascon Solution: A Novel Parameter Framework

Since 2002, GRACE and GRACE-FO have provided pioneering observations of temporal variations in Earth’s gravity field, revealing an integrated measure of mass redistribution processes within the Earth system that supports a wide range of climate-related geophysical studies. Motivated by the need for consistent, high-resolution representations of mass redistribution, we present an innovative global mass concentration (mascon) solution based on an analytical point-mass formulation. The solution relates inter-satellite K-band ranging measurements observed by GRACE and GRACE-FO missions to surface mass changes and is implemented within the open-source software GROOPS.

The resulting mascon solution employs a globally distributed set of irregularly shaped mass elements with approximately equal areas. The spatial design of the mascons is guided by physical boundary information, such as coastlines, with the aim of reducing signal leakage. Each mascon is constructed from an underlying high-resolution equal-area grid, allowing the estimation to be performed at the fine-grid level while enforcing internal consistency within individual mascons through appropriate parameter constraints. To address the ill-posed nature of mascon-based gravity field inversion, we apply a regularization strategy independent of external prior information to stabilize the solution and mitigate temporal aliasing effects in the recovered mass change signals.

The performance of the TUM mascon solution is assessed using a comprehensive set of validation approaches. Comparisons with contemporary mascon solutions from other analysis centers, as well as with other independent data sets, are conducted to assess the consistency of mass change signals and relative noise characteristics at both global and regional scales, with regional analyses focusing on selected hydrological basins and arid regions.