The measurement of ocean acidity using the depth-dependence of ambient noise
Bibliographic record
Abstract
The absorption of sound in seawater is due to the viscous and chemical relaxation of different compounds. Over the wind noise band of 1–10 kHz, the frequency dependence of the absorption is due to the mechanisms of chemical relaxation for magnesium sulfate (f > 3 kHz) and for boric acid (f < 3 kHz), which involve ionic dissociations activated and deactivated by the condensation and rarefaction of the medium by passing sound waves. Concentrations of both chemicals determine the level at which the sound is absorbed, which makes the process dependent on the salinity, temperature, and pressure in the ocean. The concentration of boric acid in the ocean is a direct measure of pH, while the concentration of magnesium sulfate is independent of pH; thus, a measurement of the frequency dependence of sound absorption may be used to determine ocean acidity. When local winds are strong (> 10 m/s), the ambient noise field is dominated by locally generated surface noise and has a depth-independent directionality and a weakly frequency and depth-dependent intensity, due to sound absorption. By comparing measurements with theory, estimates of ocean acidity can be made from the depth profiles of ambient noise. [Work supported by ONR.]
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".