On horizontal wind gradient variability from the stratosphere to the lower troposphere in the Arctic
Bibliographic record
Abstract
Previous studies have demonstrated changes in vertical wind shear in recent decades, with implications for upward‐propagating planetary waves, the stratospheric polar vortex, and tracer transport. Changes in vertical wind shear combined with horizontal gradients have also been shown to contribute to an increase in vertical gradients in tracer fields, with important implications for vertical transport. In order to explore the extent to which changes in vertical wind shear are reflected in changes to horizontal stirring, we examine horizontal wind gradient fields from the stratosphere to the lower troposphere from 1979 to 2006. Studied in particular are the spatial and temporal properties and trends for relative vorticity, divergence, strain, and the Okubo‐Weiss criterion (which monitors the competition between strain‐ and vorticity‐dominated fields) to illustrate how horizontal wind gradients have changed over the last several decades. The results from this investigation show negative vorticity and strain anomalies during winter following 1998 associated with an increase in sudden stratospheric warmings and perturbations to the polar vortex noted in recent years. Spatial distributions for relative vorticity and strain fields exhibit coherent structures near the tropopause and middle stratosphere during fall and winter, which are captured by the Okubo‐Weiss fields. Trend analyses highlight statistically significant trends in relative vorticity and Okubo‐Weiss fields during winter. The results from this investigation demonstrate that statistically significant trends exist from the stratosphere to the lower troposphere. It is hypothesized that the coupling from the lower troposphere to the upper atmosphere will be important in the development of our understanding of the response of sea ice concentrations to climate variability and change.
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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 | 0.001 |
| 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) | 0.000 | 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 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".