Ballooning Instability in the Plasma Sheet TransitionRegion in Conjunction With Nonsubstorm Auroral Wave Structures
Bibliographic record
Abstract
Abstract As an important dynamic process in the plasma sheet, ballooning instability was suggested to be responsible for unstable plasma involving azimuthal wave structures. The upward and downward alternately flowing field‐aligned currents developed in association with unstable waves may cause the finger/beading‐like auroral wave structures along the longitudinal direction, which is a common auroral feature preceding the auroral substorm poleward expansions. In our previous study, we directly evaluated the ballooning instability criterion using in situ observations in conjunction with auroral images and found that the ballooning unstable condition is satisfied in the near‐Earth plasma sheet prior to the auroral wave structures preceding substorm onset. In this study, we adopted the same method and examine the plasma sheet conditions within the regions in conjunction with weak transient auroral wave structures that fade out without further intensification and poleward expansion. The results from analyzing eight events show that no abrupt changes were found in plasma moments and field data. However, the magnetohydrodynamic ballooning instability criterion estimated from observations was satisfied shortly before the initiation of the auroral wave structures due to the changes in plasma spatial profiles. Instability develops against waves with shorter wavelength than those in ambient plasma. Weak magnetic oscillations within the Pi2 band were associated with the instability. These results suggest that the ballooning instability in the plasma sheet transition region is a plausible candidate for causing auroral wave structures during non‐substorm time. The unstable state of the plasma may not necessarily lead to favorable conditions for the substorm onset to occur.
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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 | 0.000 |
| 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) | 0.000 | 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".