Terdiurnal tide in the extended Canadian Middle Atmospheric Model (CMAM)
Bibliographic record
Abstract
We use the extended Canadian Middle Atmosphere Model (CMAM), a general circulation model (GCM), to investigate the nature of the terdiurnal tide. Temperature and horizontal winds from a model run are analyzed to delineate the character of this tide for zonal wave numbers s = −5 to +5. Descriptions of the annual mean amplitudes, seasonal variations, and total tide superposed from the migrating and 10 nonmigrating components are provided. The amplitudes and vertical wavelengths of the various components and the total terdiurnal tide are found to depend strongly on season, latitude, and altitude. The migrating terdiurnal component maximizes at mid and high latitudes with significant amplitudes (annual mean amplitude in wind (temperature) >10 m/s (K)) in the upper mesosphere and lower thermosphere (MLT) region. Between 80 and 100 km, maximum amplitudes occur in winter in both hemispheres, whereas above 100 km, maximum amplitudes occur during solstices. For the zonal wind field, the nonmigrating terdiurnal components Te5, Te3, Te4, Tw4, and Tw5 tend to peak at >50°N/S with amplitudes between 2 and 8 m/s. The other nonmigrating components maximize in the polar regions with amplitudes of 2–10 m/s. Possible generation mechanisms (solar heating and nonlinear interactions) for the migrating terdiurnal tide in the MLT region are also examined. Correlation analysis indicates that nonlinear interactions between the migrating diurnal and semidiurnal tides are unlikely to be the source of the migrating terdiurnal tide.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".