Correction of GRACE measurements of the Earth’s moment of inertia (MOI)
Abstract 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) genera...
| Published in: | Climate Dynamics |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Springer Science and Business Media LLC
2021
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1007/s00382-021-06022-1 https://link.springer.com/content/pdf/10.1007/s00382-021-06022-1.pdf https://link.springer.com/article/10.1007/s00382-021-06022-1/fulltext.html |
| Summary: | Abstract 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. |
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