Abstract
The goal of next-generation gravity missions (NGGM) is to improve the monitoring of mass transport in the Earth system by an increased space-time sampling capability as well as higher accuracies of a new generation of instrumentation, but also to continue the monitoring time series obtained by past and current missions such as GRACE and GRACE Follow-On. As the likelihood of three satellite pairs being simultaneously in orbit in the mid-term future increased, we have performed a closed-loop simulation to investigate the impact of a third pair in either polar or inclined orbit as an addition to a Bender-type constellation with NGGM instrumentation. For the additional pair, GRACE-like as well as NGGM instrumentation was tested. The analysis showed that the third pair mainly increases the redundancy of the monitoring system but does not significantly improve de-aliasing capabilities. The best-performing triple-pair scenario comprises a third inclined pair with NGGM sensors. Starting with a Bender-type constellation of a polar and an inclined satellite pair, simulation results indicate an average improvement of 11% in case of adding the third pair in a near-polar orbit, and of 21% for the third pair placed in an inclined orbit. The most important advantage of a multi-pair constellation, however, is the possibility to recover daily gravity fields with higher spatial resolution. In the case of the investigated triple-pair scenarios, a meaningful daily resolution with a maximum spherical harmonic degree of 26 can be achieved, while a higher daily parametrization up to degree 40 results in spatial aliasing and thus would need additional constraints or prior information.
Highlights
Dedicated gravimetric satellite missions like the Challenging Minisatellite Payload (CHAMP; [1]) and the Gravity Recovery and Climate Experiment (GRACE; [2]) and GRACE Follow-On (FO; [3]) missions have been providing, for nearly two decades, essential observations of the changes of the Earth’s gravity field on a global scale. This monitoring is fundamental for applications in Earth sciences, such as hydrology [4], atmosphere [5], plate tectonics [6], earthquakes [7], and glacial isostatic adjustment (GIA; [8]) as well as cryosphere [9,10]
The GRACE-like noise represents a noise level of accelerometer (ACC) and satellite-to-satellite tracking (SST) resembling the error characteristics of the instruments implemented on the GRACE mission, and an next-generation gravity missions (NGGM) noise scenario with improved ACC and laser ranging interferometer (LRI) noise characteristics
All scenarios were processed with the Wiese approach, which co-parametrizes low-resolution daily gravity field solutions and longer-term gravity field solution
Summary
Dedicated gravimetric satellite missions like the Challenging Minisatellite Payload (CHAMP; [1]) and the Gravity Recovery and Climate Experiment (GRACE; [2]) and GRACE Follow-On (FO; [3]) missions have been providing, for nearly two decades, essential observations of the changes of the Earth’s gravity field on a global scale This monitoring is fundamental for applications in Earth sciences, such as hydrology [4], atmosphere [5], plate tectonics [6], earthquakes [7], and glacial isostatic adjustment (GIA; [8]) as well as cryosphere [9,10].
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