Impact of the South-Atlantic Anomaly radiations on DORIS Ultra-Stable Oscillator: resulting effects on DORIS measurements and orbit determination for Sentinel-3A and Sentinel-6A
Bibliographic record
Abstract
Most of altimetry missions rely on both DORIS and GNSS for orbit determination purpose. For both techniques, the knowledge of a frequency reference is crucial. For the DORIS system, this reference comes from an onboard Ultra-Stable Oscillator (USO). The behaviour of this USO is affected by irradiation rates, especially in the vicinity of the South-Atlantic Anomaly (SAA) where the radiations are important. Throughout DORIS processing, the rapid variations of the USO due to radiations are not accounted, as the behaviour of the latter is only modelled by a polynomial. Consequently, high irradiations rates such as in the SAA result in higher DORIS residuals. This effect is strongly visible for stations located in the SAA region. The configuration of Sentinel-3A and Sentinel-6A where both GPS and DORIS receiver are coupled to the USO allows to mitigate this issue. Indeed, the GNSS clock is determined during the orbit determination processing. This clock can be used in state and place of the third order polynomial. This integration of the GPS clock as the modelled DORIS USO is hereby presented. The impact of this modification in the orbit determination is discussed regarding DORIS residuals at first. Notable differences are observable, especially for the DORIS stations located in the SAA. The resulting orbits are compared with the new POE-G standard orbits in order to characterize the impact of such a correction on the DORIS processing for both Sentinel-3A and Sentinel-6A.
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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 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".