Characterizing mascon grid geometries for the GRACE fast‑mascon framework

The Gravity Recovery and Climate Experiment (GRACE) mission, launched in 2002, functions as a probing instrument designed to measure temporalvariations in Earth's gravity field. The mission provides monthly gravity field solutions, expressed as spherical harmonic coefficients. These datasets form the basis for studying large-scale geophysical processes and climate-related mass transport. The framework of fast mascons provides linear mapping between surface mass densities and Level-2 monthly spherical harmonic observations. It is considered equivalent to mascons estimated from Level-1B observations, provided that the spherical harmonic solution covariances are available.In this work, we investigate three mascon grid geometries: a triangular grid, a quasi-uniform pentagonal-hexagonal grid, and a latitude-longitude equal-area rectangular grid. These grids differ in computational efficiency, representation of sphere topology, and uniform area approximation. We compare the grids based on computational efficiency and area uniformity. We attempt to answer how the global mascon grid design affects the algebraic and spectral properties of the GRACE fast mascon forward operator. We further investigate the catchment average recovery from different mascon geometries.