Coupling of dipolarization front flow bursts to substorm expansion phase phenomena within the magnetosphere and ionosphere
Bibliographic record
Abstract
Recent THEMIS spacecraft observations have shown longitudinally narrow, earthward moving, plasma sheet flow channels with large, abrupt magnetic field dipolarizations that have been referred to as dipolarization fronts. We undertake a detailed study of the subset of these events that had good quality auroral imaging. We find that many occurred during the substorm expansion phase after onset (determined by auroral intensification) and were related to auroral streamers. Both the fronts' relation to streamers and their plasma sheet changes are similar to what has been previously shown for other plasma sheet flow channels and to other flow channels seen during the expansion phases of the events considered here. Surprisingly, the dipolarization fronts examined made major contributions to substorm onset ground and space magnetic signatures. These include substorm near‐Earth dipolarization, which indicates that the current wedge may develop via a series of well‐defined, narrow, post‐onset wedge‐like structures. These also include the auroral zone ground magnetic field, which showed only modest responses to the onsets but abrupt, large responses to post‐onset dipolarization‐front‐related streamers, and midlatitude positive bays, which started near the time of streamer formation. Our observations suggest that traditional magnetic signatures of substorm onset, such as near‐Earth dipolarization, auroral‐zone negative bays, and midlatitude positive bays, may misidentify the expansion phase onset determined by auroral intensification by up to 10s of minutes for some events. It should be interesting in the future to determine the generality of the above relations between dipolarization front signatures and onset signatures.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".