Unexpected quasi-independence of colored dissolved organic matter absorption from chlorophyll-a concentration in the Southern Ocean
Bibliographic record
Abstract
Abstract. The absorption coefficient of colored dissolved organic matter (CDOM), ay, plays a critical role in driving ocean optical properties and so light attenuation and light-dependent biogeochemical cycles. In the Southern Ocean (SO), however, ay remains poorly documented because of the scarcity of in situ measurements and the absence of suitable bio-optical models. To address this gap, we derived ay in surface waters from the diffuse attenuation coefficient (Kd) derived from radiometric measurements performed by Biogeochemical-Argo floats. Sensitivity analyses indicated that the uncertainty of our estimates is mainly driven by Kd, with an overall ∼ 18 % uncertainty of ay at 380 and 412 nm based on a Monte Carlo approach. The relationships we obtained between ay and Chl in low-latitude waters are consistent with previous studies but diverge in the SO, with a much weaker dependence on Chl and a larger relative contribution to the absorption budget for clear waters. Possible reasons for this different contribution include CDOM release by sea ice melting, CDOM enrichment of surface layers through deep winter mixing, adaptation of phytoplankton physiology to cold waters and reduced photo degradation during the polar winter.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.001 | 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".