Two‐step evolution of auroral acceleration at substorm onset
Bibliographic record
Abstract
The sudden formation of parallel electric fields in the magnetosphere‐ionosphere (M‐I) coupling system is essential to complete substorm onset. From this standpoint, we focus substorm ignition on field‐aligned acceleration by studying the dynamical behavior of auroral kilometric radiation. Field‐aligned auroral acceleration shows a distinct two‐step evolution at substorm onset: the activation of low‐altitude acceleration (h ∼ 4000–5000 km) which corresponds to auroral initial brightening and the subsequent abrupt breakout of high‐altitude acceleration (h ∼ 6000–12,000 km) which corresponds to auroral breakup. Cases when only low‐altitude acceleration (first‐step evolution) is activated are pseudosubstorms. This indicates that the second evolution of field‐aligned acceleration divides full substorm from pseudosubstorm. The statistical relationship between the plasma flow burst in the plasma sheet and its response to the M‐I coupling region shows that about 65% of flow bursts cause pseudobreakup/initial brightening (low‐altitude acceleration) and one third of them develops into full substorm (low‐altitude and high‐altitude accelerations), while the magnitude of flow velocity does not necessarily distinguish between pseudobreakup and full substorm. This suggests that some plasma flow bursts originate field‐aligned current which first enhance low‐altitude acceleration, and the increasing field‐aligned current induces second acceleration above the preexisting low‐altitude acceleration as a consequence of current/current‐driven instabilities. In this sense, the substorm is finally ignited in the auroral M‐I coupling region.
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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".