Wintertime compound extremes in Europe and North America : from dynamics to predictability
Bibliographic record
Abstract
This thesis examines the co-occurrence of wintertime low temperature extremes (cold spells) over North America and wet or windy extremes over Europe. Prolonged (≅ 5 days) North American cold spells can be associated with both upstream and downstream anomalous large-scale atmospheric flows, the latter modulating extreme weather occurrences over Europe. The approximate co-occurrence of European wet or windy extremes with North American cold spells is temporally and spatially dependent on the location of cold spells. We identify three broad regional clusters of cold spells: Central Canada: cold spells are predominantly preceded by Iberian precipitation extremes. Eastern United States: occurrences of both wind and precipitation extremes in Iberia before and after the cold spell. East Canada: cold spells are predominantly followed by wind extremes over the British Isles and Northern Europe. We show that cold spells over these three regions are associated with distinct storm track and jet stream anomalies over the North Atlantic. Iberia experiences a higher number of extratropical cyclones during Central Canada cold spells due to an equatorward displacement of the jet. However, the propagation of extratropical cyclones over Europe is limited due to a Scandinavian block-type configuration over Northern Europe. Eastern United States cold spells show a similar configuration to Central Canada. However, this configuration does not show the Scandinavian block-type feature, resulting in a higher number of extratropical cyclones affecting Iberia and Southern Europe. Eastern Canada cold spells are associated with an extended and accelerated jet over Northern Europe. As a result, the UK, France and Northern Europe experience more intense extratropical cyclones on average, with the accelerated jet resulting in stronger extratropical cyclones throughout the North Atlantic in general. These results evidence the existence of a systematic statistical and dynamical connection between North American cold spells and European wet or windy extremes.
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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 | 0.001 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".