On the Dynamics of the Formation of the Kelvin Cat’s-Eye in Tropical Cyclogenesis. Part I: Climatological Investigation
Bibliographic record
Abstract
Abstract Motivated by Dunkerton et al., a climatological study of 54 developing easterly waves in 1998–2001 was performed. Time-lagged composites in a translating reference frame following the disturbances indicate a weak meridional potential vorticity (PV) gradient of the easterly jet and a cyclonic critical layer located slightly to the south of the weak PV gradient, consistent with previous findings in the marsupial paradigm. Using a closed PV contour as a criterion for the formation of the cat’s-eye, it was shown that on average it takes ~2.6 days for open PV contours to transform to a closed coherent structure. Bootstrap analysis was then applied to determine the reliability of the easterly wave–like pattern in the composite perturbation PV analysis. It is suggested that the coexistence of a nonlinear critical layer and a region of weak meridional PV gradient over several days, found to occur in only ~25% of the easterly waves, might be a major factor to distinguish developing and nondeveloping disturbances. This finding may explain why only a small fraction of easterly waves contribute to tropical cyclogenesis. Additionally, an analytic time scale of the form was obtained, where Q is the mass sink, ε is the amplitude of the initial disturbance, and τ is the cat’s-eye formation time that governs the onset of nonlinearity for forced disturbances on a parabolic jet critical layer. This time scale is consistent with that found in 54 cases of easterly waves that developed into named storms, highlighting the importance of nonlinear and diabatic processes in cat’s-eye formation.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".