Correction of GRACE measurements of the Earth’s moment of inertia (MOI)

• Published in: Climate dynamics Vol. 58; no. 9-10; pp. 2525 - 2538
• Main Authors: Ren, Diandong, Leslie, Lance M., Huang, Ying, Hu, Aixue
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2022; Springer; Springer Nature B.V
• Subjects: Atmosphere; Climate; Climate change; Climatology; Cryosphere; data collection; Datasets; Day length; Earth and Environmental Science; Earth Sciences; Environmental aspects; Estimates; Geophysics/Geodesy; Glaciation; Global warming; GRACE (experiment); Gravity; Greenland; Greenland ice sheet; Hydrology; ice; Ice sheets; Inertia; Laboratories; Mass; Measurement; Moments of inertia; Ocean circulation; Oceanography; Precipitation; Sea level; t-test; time series analysis; Australia; Greenland; Climate change impacts; Greenland ice sheet; Total mass balance; GRACE; Earth’s moment of inertia
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-021-06022-1

The widely used 15-year Gravity Recovery and Climate Experiment (GRACE) data sets do not conserve global total mass. They have a spurious decreasing trend of ~ 280 Gt/year. Various regions contribute differently to the global total mass loss error, with the Greenland Ice Sheet (GrIS) generating ~ 10% of the error alone. Atmospheric parameters from reanalysis datasets drive a well-tested ice model to generate mass variation time series over the GrIS for 2002–2015. Because shorter timescale spikes of ~ 10–30 Gt in GRACE measurements are physically based, only the overall trend of ~ 30 Gt/year requires correcting. A more accurate mass loss rate estimate for 2002–2015 is ~ 120 Gt/year, considerably below previous estimates. With the water redistribution to lower latitudes and other effects from a warming climate, the nontidal Earth moment of inertia (MOI) also increases. After rectification, the GRACE measured mass redistribution shows a steady, statistically robust (passed a two-tailed t-test at p = 0.04 for dof = 15) rate of MOI increase reaching ~ 10.1 × 10 27  kg m 2 /year, equivalent to a 10.91 μs/year increase in the length of a day, during 2002–2017.