Abstract
Commonly used mass-concentration (mascon) solutions estimated from Level-1B Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On data, provided by processing centers such as the Jet Propulsion Laboratory (JPL) or the Goddard Space Flight Center (GSFC), do not give users control over the placement of mascons or inversion assumptions, such as regularization. While a few studies have focused on regional or global mascon optimization from spherical harmonics data, a global optimization based on the geometry of geophysical signal as a standardized product with user-defined points has not been addressed. Finding the optimal configuration with enough coverage to account for far-field leakage is not a trivial task and is often approached in an ad-hoc manner, if at all. Here, we present an automated approach to defining non-uniform, global mascon solutions that focus on a region of interest specified by the user, while maintaining few global degrees of freedom to minimize noise and leakage. We showcase our approach in High Mountain Asia (HMA) and Alaska, and compare the results with global uniform mascon solutions from range-rate data. We show that the custom mascon solutions can lead to improved regional trends due to a more careful sampling of geophysically distinct regions. In addition, the custom mascon solutions exhibit different seasonal variation compared to the regularized solutions. Our open-source pipeline will allow the community to quickly and efficiently develop optimized global mascon solutions for an arbitrary point or polygon anywhere on the surface of the Earth.
Highlights
Time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and the GRACE Follow-On (FO) missions have enabled an unprecedented analysis of mass change on the surface of the earth since April 2002 [1]
Time-variable gravity measurements by GRACE/GRACE-FO can be represented by spherical harmonic solutions [4], which are provided as Level-2 data products by the mission Science Data System (SDS) centers
The spatial variability of geophysical mass change signals in this area dictates the need for smaller mascons, which inevitably results in a higher amount of ringing due to the truncated nature of GRACE harmonics
Summary
Time-variable gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and the GRACE Follow-On (FO) missions have enabled an unprecedented analysis of mass change on the surface of the earth since April 2002 [1]. The resulting time-variable gravity product is provided with a monthly temporal resolution and a spatial resolution of roughly 300 km [1,3]. Time-variable gravity measurements by GRACE/GRACE-FO can be represented by spherical harmonic solutions [4], which are provided as Level-2 data products by the mission Science Data System (SDS) centers Given the limited resolution of the data at degree and order 60 (∼330 km), along with the random noise that increases as a function of spherical harmonic degree [6], these solutions require post-processing techniques in order to obtain regional estimates of mass change with minimal noise and leakage [7]
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