Investigating surface gravity and height variations due to glacial isostatic adjustment: A comparative study using GRACE, GRACE-FO and absolute gravity measurements data in Canada and Fennoscandia
Bibliographic record
Abstract
In this study, we investigate the gravity changes ( ) associated with the Global Isostatic Adjustment (GIA) and their correlation with land uplift rates ( ) using GRACE and GRACE Follow-on data, spanning 2003 to 2023. We further validate our results using repeated absolute gravity measurements. We analyze the absolute gravity measurements collected in Canada and Fennoscandia since the 1990s and 1960s, respectively. The novelty involves applying the Sjöberg and Bagherbandi (2020) methodology to Canadian data using GRACE-derived upper mantle density and comparing the results with the terrestrial absolute gravimetry results. One of the aims of this study is also to assess the methods effectiveness in Canada, as was previously done in Fennoscandia. In addition, this study explores the similarities and the relationship between the gravity field change with other Earth’s interior parameters (e.g. density, viscosity, etc.), that offers new insights into their potential connections and understanding regional geodynamics. For Canada, we process the raw gravity observations, considering instrument precision and weighting, applying systematic corrections (Earth tides, polar motion, ocean loading, and atmospheric pressure effects), standardizing measurements to a uniform height using the vertical gravity gradient correction, implementing a rigorous drop selection and filtering process, and using a filter to minimize short-term environmental variations. For Fennoscandia, we use the processed absolute gravity data published by Olsson et al. (2019). We also estimate upper mantle density, associated with viscous mass flow in the mantle, and temporal variations in surface gravity changes ( ) using GRACE and GRACE-FO data. Finally, the obtained ratio is calculated to be compared with terrestrial absolute gravity measurements and also compared with the previously published results to assess the obtained outcomes. The results derived from GRACE and GRACE Follow-on data show that the ratios between surface gravity and height changes are −0.152 ± 0.010 μGal/mm in Canada and −0.156 ± 0.016 μGal/mm in Fennoscandia aligning closely with findings from terrestrial gravity observations. These values correspond to upper mantle densities of approximately 3736 ± 239 kg/m 3 and 3641 ± 382 kg/m 3 in Canada and Fennoscandia, respectively. • Gravity vs. uplift rates in Canada and Fennoscandia are analyzed using ground data. • GRACE and GRACE-FO satellite data are used to derive gravity-uplift ratios. • The study compares GRACE results with those from terrestrial gravimetry methods.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| 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".