Characteristics of Small‐Scale Gravity Waves in the Arctic Winter Mesosphere
Bibliographic record
Abstract
Abstract Observational data sets in the polar middle atmosphere are extremely valuable for understanding the polar dynamics and coupling between lower and middle atmosphere. Using the long‐term data sets observed with an OH all‐sky imager, a Fabry‐Perot Interferometer at Resolute Bay Observatory, Canada (74.7°N, 94.9°W), Microwave Limb Sounder and reanalysis data, we study the characteristics of small‐scale gravity waves (GWs) with the horizontal wavelength less than 20 km in the Arctic winter mesosphere during 2014–2016. Most GWs propagate nearly against the mesospheric and stratospheric winds, consistent with the wind filtering theory. A small amount (7 of 36 cases) of small‐scale GWs in large regions (area >1/2 of the whole image) propagate nearly westward with slower phase speeds, larger horizontal wavelengths, and longer periods than those in limited regions. We also find that multiple GWs with different propagating directions can sometimes occur simultaneously. This is likely due to different wave sources and/or the ducted region in the atmosphere. The observed small‐scale GWs may also likely be excited in the mesopause region, such as secondary wave generated by primary wave breaking or a result of baroclinic instability processed in the stratosphere and the interaction of planetary waves with the background winds. In addition, almost all of the small‐scale GWs occurred during the strong El Niño and anomalous quasi‐biennial oscillation events in 2015/2016 winter.
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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 | 0.000 |
| 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 | 0.000 | 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".