Assessment of temporal variations of geoid, ellipsoidal and orthometric heights at proposed IHRF sites using space geodetic data
Bibliographic record
Abstract
Abstract The determination of accurate geoid, ellipsoidal and orthometric heights is essential for applications related to surveying engineering, geodetic and geoscience research. The International Association of Geodesy (IAG) defined the International Height Reference System (IHRS) as the conventional gravity field-related global height system. The realization of the IHRS to establish an International Height Reference Frame (IHRF) and its temporal variations, is an ongoing geodetic task. The objective of this research is to assess temporal variations of geoid, ellipsoidal and orthometric heights at proposed IHRF sites using space geodetic data, namely Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO), Global Navigation Satellite Systems (GNSS), Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) and hydrological model. GRACE/GRACE-FO-based and GLDAS-based Global Geopotential Models were utilized to determine temporal variations of geoid height (Δ N ) and time-dependent changes of ellipsoidal height (Δ h ) at proposed IHRF sites. Moreover, Δ h at proposed IHRF sites were also obtained from GNSS, VLBI, SLR and DORIS solutions. Temporal variations of orthometric height (Δ H ) at proposed IHRF sites were determined by combining Δ N and Δ h . Results reveal that Δ N , Δ h , and Δ H at proposed IHRF sites are not negligible as they can reach several centimetres in terms of seasonal variations and at the and 1 cm level annually. These Δ N , Δ h , and Δ H would be required for the modernization and unification of international/national vertical datums in addition to contemporary requirements for precise height measurements.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| 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) | 0.000 | 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 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".