The impact of new accelerometer transplant data (ACH) on GRACE Follow‐On along‐orbit inter‐satellite laser ranging observations and monthly time‐variable gravity and mascon solutions

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Abstract

GRACE-D accelerometer data show significant bias jumps since one month after the launch of the GRACE Follow-On (GRACE-FO) satellites in May 2018, making them inapplicable for correcting GRACE-FO products for non-gravitational accelerations. The GRACE-FO Science Data System (SDS) compensated this issue by transplanting the GRACE-C accelerometer data toward that of GRACE-D. Recently, GRACE-FO SDS implemented an updated transplant method, used in the latest release of GRACE-FO data. Here, we examine the impact of updated accelerometer transplant data (ACH) on GRACE-FO measurements at all levels: (a) Level-1B inter-satellite laser ranging residuals measured along satellite orbit, (b) Level-2 time-variable gravity solutions from all SDS centers (JPL, CSR, and GFZ), and (c) Level-3 mascon solutions. We show that inter-satellite laser ranging residuals are modified at low frequencies below 1 mHz, affecting the along-orbit analysis of large-scale time-variable gravity signals. When mapped into monthly Level-2 spherical harmonic coefficients of geopotential, the low-frequency change in inter-satellite ranging residuals leads to substantial improvement of coefficients associated with resonant orders (i.e., 15, 30, 45, etc.) and C30. We also present an improved SLR-derived C30 which significantly improves the agreement with updated GRACE-FO C30 at seasonal and interannual timescales. Moreover, we demonstrate the noise reduction in mass change estimates from new GRACE-FO Level-2 data over oceans, Greenland, and Antarctica for all SDS solutions. GRACE-FO mascon solutions show a moderate change in the updated release. Our comprehensive analyses demonstrate high-quality estimates of non-gravitational accelerations by the updated transplant method, resulting in more accurate GRACE-FO time-variable gravity and mass change observations.

Details

Original languageEnglish
Article numbere2023JB026740
Number of pages25
JournalJournal of Geophysical Research: Solid Earth
Volume128
Issue number6
Publication statusPublished - 11 Jun 2023
Peer-reviewedYes

External IDs

Scopus 85163627063
ORCID /0000-0002-1917-2027/work/141544601
ORCID /0000-0001-5226-7231/work/142240979
ORCID /0000-0001-5797-244X/work/142246562

Keywords

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Keywords

  • accelerometer transplant, GRACE Follow-On, laser ranging interferometer, mass change, non-gravitational accelerations, time-variable gravity

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