Polar cap bifurcation during steady‐state northward interplanetary magnetic field with ∣<i>B</i><sub><i>Y</i></sub>∣ ∼ <i>B</i><sub><i>Z</i></sub>
Bibliographic record
Abstract
In this paper, for steady‐state northward interplanetary magnetic field (IMF) with ∣BY∣ ∼ BZ, we describe a new merging sequence that results in polar cap bifurcation and accompanying paired “exchange cells” in the ionospheric convection pattern. Although the IMF is northward, it reconnects with the closed geomagnetic field on the dayside high‐latitude magnetopause, creating two types of open geomagnetic field lines. For the first type the neutral point and the foot point are in the same hemisphere; for the second type the neutral point and the foot point are in opposite hemispheres. The latter type of field lines slips on the magnetopause in the azimuthal direction opposite to the normal BY‐ associated flux transport and forms an overdraped tail lobe. The ionospheric signature of this overdraped lobe is the appearance of an open magnetic flux island inside the dawn/dusk plasma sheet (i.e., polar cap bifurcation). For BY > 0 the island emerges in the duskside (dawnside) plasma sheet in the northern (southern) ionosphere and conversely for BY < 0. The overdraped field lines which have slipped on the magnetopause then reconnect with closed geomagnetic field lines in the opposite hemisphere to the foot points, thereby transferring the open magnetic flux to the nightside convection system and maintaining the steady‐state magnetic flux circulation. As a result, paired ionospheric convection cells form which exchange magnetic flux. For BY > 0 the pair is located in the noon‐dusk and midnight‐dawn (dawn‐noon and dusk‐midnight) quadrants of the northern (southern) ionosphere; for BY < 0 a mirror image with respect to the noon‐midnight meridian applies to the convection pattern. We demonstrate observational evidence that supports this 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) | 0.002 | 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".