A study of extratropical transition in the Western North Atlantic Ocean, 1963–1996
Bibliographic record
Abstract
A synoptic‐ dynamic climatology of the forty‐five extratropical‐transitioning tropical cyclones, (as compiled by the United States National Hurricane Center) travelling through offshore regions of the North American east coast during the 1963–96 hurricane seasons, is presented. The National Centers for Environmental Prediction global reanalyses of geopotential height are used to construct large‐scale circulation features associated with the passage of these systems. Soundings of six near‐track stations are used to study the stratification of temperature and moisture during the cyclones ‘ passage. Sea‐surface temperature (SST) structures are also studied with respect to these events. Primary results of the study include: a) a statistically‐significant 1000–500 hPa warm anomaly (with respect to a 1963–96 climatology) persists over central and eastern North America during the two‐day period prior to the passage of the tropical systems into the Canadian Maritime provinces; b) a northwestward extension of the surface subtropical anticyclone exists over the Canadian Atlantic Provinces during the two‐day period prior to the arrival of the cyclone; c) the tropical cyclone's convectively‐unstable tropical air mass is maintained for at least eighteen hours after transition; and d) the presence of quasi‐geostrophic forcing for ascent, typically seen in extratropical cyclones, is observed during periods in which the systems are still classified as tropical cyclones. This forcing for ascent continues during the extratropical transformation, and typically occurs ahead and to the left of the storm track. Additionally, these transforming systems travel through a region of SST gradients that are anomalously strong compared with the climatology for that region. Storms are also classified according to whether they were deepening or filling. These classifications were composited to distinguish circulation structures unique to each classification. Considering that several of the systems passing through the maritime‐coastal regions are filling and several are intensifying, we distinguish the circulation structures between the deepening and filling systems. The primary distinction of the deepening extratropical transition is the statistically‐significant colder tropospheric air mass to the north of the storm track. Such a finding is similar to that found in other studies for cold‐season deepening extratropical cyclones.
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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 | 0.002 |
| Science and technology studies | 0.001 | 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".