The possible 5.9 years oscillation identification from superconducting gravimeter observations
Bibliographic record
Abstract
Abstract. Surface gravity changes aroused by the periodic ∼5.9 years oscillation (referred to as SYO) are important for understanding its origin and may further constrain Earth’s deep interior dynamics, but such signals have not been directly observed. In this study, we combine multiple spectra methods to analyze six usable superconducting gravimeter (SG) residual series in Western Europe, Canada, and Australia between 1996 and 2019; and try to extract the possible SYO signals from surface gravity observations. The amplitudes of the recovered possible SYO gravity changes vary from 0.5 to 0.9 μGal at different observatories. Comparisons with a derived time‐varying gravity model indicate that the phases of gravity SYO may also have a spherical harmonic Y22 spatial distribution. The corresponding amplitude transform factors δ/h between the observed and modeled signals for different SG stations are about 2.9, greater than the ratio of ~1.9 for the corresponding tidal Love numbers. The observed amplitudes are also quite different from the predictions of the possible mechanisms suggested by previous studies. Although the SYO is believed to have originated from core motions, our findings mean that the potential physical mechanism should be much more complicated than any existing one. We suggest that the MAC waves arising from the interplay between Magnetic, Archimedes, and Coriolis forces could be a possible excitation source of the SYO. We believe our gravity observation results should help interpret the SYO in the future.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".