Impact of Westward-Propagating ISO over Mid-High-Latitude Eurasia on SSW during Boreal Winter
Bibliographic record
Abstract
Abstract In this study, the impact of intraseasonal oscillation (ISO) over mid-high-latitude Eurasia on stratosphere sudden warming (SSW) events during boreal winter is examined based on the NCEP–NCAR reanalysis data. It is found that the dominant ISO periodicity is 10–30 days. By extended empirical orthogonal function, two leading ISO modes with opposite directions of westward and eastward propagation are extracted. Since the eastward-propagating mode was involved by previous studies, this study is focused on the westward-propagating one. As revealed, the westward-propagating ISO propagates from the Canadian Arctic Archipelago to western Europe, which is dominated by waves 1–2. The analysis of lead–lag correlation and phase division indicates that SSW events prefer to occur at the time of lagging the westward-propagating ISO phase 2 by 7–9 days. The diagnosis of the dynamic process of ISO impacting SSW suggests that during the westward journey of the ISO, the corresponding pattern leads to sea ice loss over the Barents–Kara Sea, which emanates upward-propagating planetary waves. At the same time, the ISO circulation expands the easterly anomalies, which weakens westerly flow that favors the planetary waves of wave 1 and wave 2 propagating upward into the stratosphere to affect the onset of SSW. By applying the subseasonal-to-seasonal (S2S) reforecast data from the ECMWF model, the probability density functions of zonal wind anomaly verify the impact of westward-propagating ISO on SSW. significance statement The intraseasonal oscillation (ISO) is a vital prediction source for the forecast of extreme weather and climate in both the troposphere and the stratosphere, but the relationship between the mid-high-latitude one and stratospheric extreme weather events lacks research. The purpose of this study is to understand how the ISO over mid-high-latitude Eurasia affects the stratosphere sudden warming (SSW). Our results find that the westward-propagating ISO can impact the onset of SSW events by leading to sea ice loss over the Barents–Kara Sea and the expansion of easterly anomalies. This provides a new clue for the extended-range forecast of SSW.
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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 | 0.000 | 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".