Bridging the gap between GRACE and GRACE follow-on monthly gravity field solutions using improved multichannel singular spectrum analysis

Abstract

The gap between the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-on mission (GRACE-FO) is a crucial problem, leading to discontinuous global mass change information from time-variable gravity field solutions. We aim to use the improved Multichannel Singular Spectrum Analysis (MSSA) to fill the gap and reconstruct the continual global mass change signals in this study. The one-year gravity field gap is filled with improved MSSA based on the Release 06 (RL06) monthly gravity field models provided by Center for Space Research (CSR) truncated to d/o 60 and further compared with Swarm monthly solutions (d/o 40). The results show that the infilled gravity field models agree with the Swarm solutions, indicating that improved MSSA can reliably bridge the gap between GRACE and GRACE-FO missions. Moreover, relative to the Global Land Data Assimilation System (GLDAS) Noah model, the infilled gravity field models have higher correlation coefficients and smaller root mean squared errors than Swarm solutions for the mass change signals over Congo, Lena and Fraser river basins. According to the simulation results using the same gap as GRACE and GRACE-FO, improved MSSA can fill the gap very efficiently and reliably in 25 major river basins over the World.