Stepwise tailward retreat of magnetic reconnection: THEMIS observations of an auroral substorm
Bibliographic record
Abstract
Abstract Auroral stepwise poleward expansions were clarified by investigating a multiple‐onset substorm that occurred on 27 February 2009. Five successive auroral brightenings were identified in all‐sky images, occurring at approximately 10 min intervals. The first brightening was a faint precursor. The second brightening had a wide longitude; thus, it represented the Akasofu substorm onset. Other brightenings expanded poleward; thus, they were interpreted to be auroral breakups. These breakups occurred stepwise; that is, later breakups were initiated at higher latitudes. Corresponding reconnection signatures were studied using Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite observations between 8 and 24 RE down the magnetotail. The Akasofu substorm onset was not accompanied by a clear reconnection signature in the tail. In contrast, the three subsequent auroral breakups occurred simultaneously (within a few minutes) with three successive fast flows at 24 RE; thus, these were interpreted to be associated with impulsive reconnection episodes. These three fast flows consisted of a tailward flow and two subsequent earthward flows. The flow reversal at the second breakup indicated that a tailward retreat of the near‐Earth reconnection site occurred during the substorm expansion phase. In addition, the earthward flow at the third breakup was consistent with the classic tailward retreat near the end of the expansion phase; therefore, the tailward retreat is likely to have occurred in a stepwise manner. We interpreted the stepwise characteristics of the tailward retreat and poleward expansion to be potentially associated by a stepwise magnetic flux pileup.
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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 | 0.001 |
| 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".