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. RESUM [Traduit par la rdaction] On prsente une climatologie synoptique-dynamique des quarante-cinq dpressions tropicales en transition extratropicale (telles que compiles par le United States National Hurricane Center) qui ont travers les rgions au large de la cte est de l'Amrique du Nord durant les saisons d'ouragans de 1963 1996. Les ranalyses globales de la hauteur gopotentielle des National Centers for EnvironmentalPrediction sont utilises pour construire les caractristiques de circulation grande chelle associes au passage de ces systmes.Les sondages de six stations situes prs des trajectoires permettent d'tudier la stratification de la temprature et de l'humidit au moment du passage des dpressions.On tudie aussi la structure de la temprature de surface de la mer (TSM) par rapport ces vnements.Les principaux rsultats de l'tude incluent : a) une anomalie chaude dans la couche 1000-500 hPa (par rapport la climatologie de la priode statistiquement significative, qui persiste dans le centre et dans l'est de l'Amrique du Nord durant les deux jours qui prcdent le passage du systme tropical dans les provinces Maritimes canadiennes; b) il y a une extension de l'anticyclone subtropical en direction nord-ouest au-dessus des provinces canadiennes de l'Atlantique durant les deux jours qui prcdent l'arrive de la dpression; c) la masse d'air tropical convectivement instable de la dpression tropicale perdure au moins dix-huit heures aprs la transition; et d) on observe un forage quasi gostrophique d'ascendance, typiquement prsent dans les dpressions extratropicales, durant les priodes o les systmes sont encore classs comme des dpressions tropicales.Ce forage d'ascendance continue pendant la transformation extratropicale et se produit typiquement en avant et gauche de la trajectoire de la dpression.De plus, ces systmes en transformation voyagent dans une rgion de gradients de TSM anormalement fort comparativement la climatologie de la rgion.Les dpressions sont aussi classifies selon qu'elles se creusaient ou se remplissaient.Ces classifications ont t tablies pour distinguer les structures de circulation particulires chaque classification.Compte tenu que plusieurs des systmes passant dans les rgions maritimes ctires se creusent et plusieurs s 'intensifient, nous
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.001 | 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 teacher head, 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".