Present‐day secular variations in the low‐degree harmonics of the geopotential: Sensitivity analysis on spherically symmetric Earth models
Bibliographic record
Abstract
We predict present‐day rates of change of the long‐wavelength components of the Earth's geopotential due to the late Pleistocene glacial cycles (hereinafter referred to as glacial isostatic adjustment, or GIA). These predictions are generated using spherically symmetric, self‐gravitating, (Maxwell) viscoelastic Earth models. Previous studies have generally considered only zonal (i.e., azimuthally independent) harmonics, or the so‐called coefficients. We extend these efforts to focus on the nonzonal harmonics and explore the sensitivity of our predictions to changes in a variety of model inputs. As an example, we examine the influence on the GIA predictions of ignoring rotational perturbations and assuming an elastically incompressible model and find that these assumptions can have a significant impact on the degree‐2, order‐1 coefficients, while the other harmonics are generally affected by <10%. Though the GIA predictions are generally insensitive to variations in lithospheric thickness and upper mantle viscosity, reasonable variations in either lower mantle viscosity or the late Pleistocene ice history will have a more significant effect. Mindful of upcoming dedicated gravity missions, we show that predictions of the GIA‐induced changes of the geoid can vary by at least 0.5 mm yr −1 over a plausible range of Earth and ice models.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.004 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".