Global free oscillations of the atmosphere and secondary planetary waves in the mesosphere and lower thermosphere region during August/September time conditions
Bibliographic record
Abstract
Wind measurements made using ground‐based mesosphere and lower thermosphere radar systems at Sheffield, UK (2°W, 53°N) and Saskatoon, Canada (107°W, 52°N) show an increase in long‐period planetary wave (PW) activity at the end of August until the middle of September 1993. Some of these waves can be identified with the well‐known normal atmospheric modes; however, the westward propagating wave with zonal wave number one (m = 1) and a period of about 6.5 days observed during this time interval cannot be explained using the classical theory of free atmospheric oscillations. Analysis of the UKMO assimilated fields shows that in the stratosphere the 7‐day wave with m = 2 increases in amplitude during the time interval considered, and there exists a strong stationary planetary wave (SPW) with m = 1. A steady state two‐dimensional numerical model of planetary waves has been used to simulate the free atmospheric oscillations and secondary planetary wave, which arises from a nonlinear interaction between the second asymmetric normal mode with m = 2 (the 7‐day wave) and SPW with m = 1. The results of simulation show that an increase in long‐period PW activity during August/September can be explained by seasonal changes of the zonal mean flow, which influence the wave propagation conditions, and that one of the possible sources for the 6.5‐day wave is a nonlinear interaction between the 7‐day wave and SPW with m = 1. It is suggested that the 6.5‐day wave with m = 1 be referred to as a “secondary normal mode,” which has been generated by random meteorological motions in the lower atmosphere and involving interaction with a SPW of wave number 1.
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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 | 0.000 | 0.000 |
| 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) | 0.001 | 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".