Plasma sheet Pi2 pulsations associated with bursty bulk flows
Bibliographic record
Abstract
Abstract There is a debate as to whether magnetic Pi2 pulsations (0.006–0.025 Hz) observed in the plasma sheet and on the ground are triggered by the earthward moving bursty bulk flows (BBFs) from midtail or distant tail or are caused by the substorm plasma instabilities initiated in the near‐Earth plasma sheet. To resolve this debate, we conducted case and statistical studies of enhanced plasma sheet Pi2 pulsations using Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations from X~−30 RE to X~−8 RE. The case studies show that for both substorm‐related and quiet time BBFs, enhanced Pi2 oscillations are observed in front of BBFs from midtail to the near‐Earth plasma sheet. The oscillations intensify 1–4 min prior to the substantial flow enhancement, and usually initiate within several narrow discrete frequency bands, with lower frequencies intensifying earlier. We further examined the wave properties using low‐frequency MHD fitting method and found that one or more discrete waves for each event are magnetosonic waves. Our statistical study of 364 BBFs shows that Pi2 pulsations are commonly associated with BBFs throughout the plasma sheet. The lowest‐frequency oscillations usually appear below 0.01 Hz, and the strongest power oscillations appear at ~0.01 Hz or higher frequencies. We found that over 75% of the discrete oscillations are magnetosonic waves, and that 70%–75% of them are slow mode. These suggest that plasma sheet Pi2 pulsations are likely triggered by BBFs in the entire plasma sheet regardless of substorm onsets.
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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 | 0.000 |
| 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".