Evaluating Sentinel-2A atmospherically corrected reflectance using the 6SV model
Bibliographic record
Abstract
In this study, the Bottom-Of-Atmosphere (BOA) reflectance over Egbert, Ontario, Canada on September 24, 2016, as obtained by the Sentinel-2A Multi-Spectral Imager and corrected by the Sentinel-2 atmospheric Correction (Sen2Cor) software, was evaluated based on the 6SV atmospherically corrected reflectance. The aerosol and water vapor parameters used in the 6SV model were obtained from the AERONET data. The evaluation results showed that for the visible bands, the Sen2Cor BOA reflectance was lower than the 6SV BOA reflectance, with a maximum relative bias of -36.5%, due to an overestimation of the aerosol optical depth retrieved by Sen2Cor. The bias of the BOA reflectance could also affect the vegetation index (VI) calculation. Four VIs were calculated and compared using the different BOA reflectance. The maximum relative bias was 18.2%. The study shows that the BOA reflectance corrected by Sen2Cor should be treated with some degree of caution, especially for the visible bands and VIs.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".