Westward traveling surges: Sliding along boundary arcs and distinction from onset arc brightening
Bibliographic record
Abstract
After onset, auroral brightening rapidly spreads azimuthally along the onset arc, typically, but not always, extending substantially farther westward than eastward. Expansion‐phase auroras also expand poleward and can contact an arc along the auroral poleward boundary. For such events, we find that poleward expansion of the region of active aurora accelerates after contact, forming a bulge region that protrudes into the preexisting polar cap and expands westward as the westward traveling surge. This westward motion is slower than, and initiates later than, the azimuthal spreading of the onset arc brightening. The poleward boundary arc remains connected to the surge as the surge slides along the equatorward moving edge of the boundary arc, and this connection appears to set off the westward traveling, poleward protruding activity of the surge via localized polar cap flow adjacent to the boundary arc. Ground magnetic signatures show a relatively weak H component depression moving westward with the onset arc brightening, and a delayed substantially larger depression moving with the westward propagating surge that must be associated with a substantially larger westward ionospheric current. The clear distinction between onset arc brightening and the westward traveling surge seen in auroral and magnetometer current signatures implies that their underlying processes are very different. Evidence suggests that flow channels adjacent to the boundary arc possibly feed surge development. These results are consistent with current wedge formation being more associated with post‐onset activity than with onset, and with flow channels from the polar cap being important for surge/bulge development.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".