High‐latitude reconnection effect observed at the dayside dip equator as a precursor of a sudden impulse
Bibliographic record
Abstract
Geomagnetic sudden impulses (SI) observed at the dayside dip equator normally show a decrease and then an increase in the H magnetic field component, i.e., a preliminary reverse impulse (PRI) followed by a main impulse. Using global geomagnetic field measurements, we examine an unusual SI event observed at the dayside dip equator, which shows a clear precursor ∼1 min before the PRI onset. The precursor was observed simultaneously at both the dayside dip equator and in the southern polar region but was not observed at all in the northern polar region. The global ground variations after the PRI onset were, however, consistent with a conventional SI model of the magnetospheric response to a sudden enhancement of the solar wind dynamic pressure. Considering that the interplanetary magnetic field Bx, By, and Bz components were positive with the By component dominant for this event, we suggest that the SI precursor was caused by high‐latitude magnetic reconnection that occurred only (or first) in the dawn quadrant of the southern hemisphere, the effect of which has for the first time been clearly identified at the dayside dip equator. This implies that electric field effects occurring in the polar ionosphere due to magnetopause reconnection may be rapidly monitored at the dayside dip equator. In addition, we argue that the quasi‐simultaneous (time difference is less than 10 s) appearance of the disturbance fields both in the polar region and at the dip equator confirmed in this study is extremely important for theoretically explaining the transmission of the polar electric field to the dayside dip equator, because different theories give different travel times for a disturbance field propagating from polar region to the dip equator. Our observations lend strong evidence for validity of the waveguide model.
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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".