Simultaneous appearance of isolated auroral arcs and Pc 1 geomagnetic pulsations at subauroral latitudes
Bibliographic record
Abstract
We have been conducting observations of aurora and geomagnetic pulsations at Athabasca, Canada, located at a subauroral latitude (magnetic latitude: 62°, L ∼ 4.6), using an all‐sky imager and an induction magnetometer. Isolated auroral arcs at wavelengths of 557.7 nm, 630.0 nm, and 486.1 nm (H β ) were often observed at latitudes separated equatorward from the main auroral oval. From a 1‐year observation (4 September 2005 to 3 September 2006), we found 13 isolated arc events. All these isolated arcs occurred coincidentally with Pc 1 geomagnetic pulsations, although there were nine other Pc 1 events without isolated arcs in the field of view of the imager. The arcs were observed in both pre‐ and post‐midnight sectors and tended to appear during the late recovery phase of geomagnetic storms. The isolated arcs had limited latitudinal and longitudinal widths of less than 230 km and 250–800 km, respectively. We found that as isolated arcs moved equatorward (poleward), the frequencies of the simultaneous Pc 1 pulsations increased (decreased). Using the Tsyganenko‐02 magnetic field model, the observed Pc 1 frequencies were almost the same as the frequencies of He + electromagnetic ion cyclotron (EMIC) waves at the equatorial plane connected to observed isolated arcs. These results indicate that interactions of spatially localized EMIC waves with ring current ions cause high‐energy ion precipitation and associated isolated auroras at subauroral latitudes. These results also imply that the dynamics and instabilities in the inner magnetosphere can be monitored as low‐latitude auroral emissions away from the ordinary auroral oval.
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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".