Nighttime vertical plasma drifts and the occurrence of sunrise undulation at the dip equator: A study using Jicamarca incoherent backscatter radar measurements
Bibliographic record
Abstract
The absence of photoionization, in combination with sustained downward plasma motion at night, means that the F region can be severely depleted at the magnetic equator in the morning. As a result, at sunrise, there can be a sudden upward jump in altitude of the F region peak followed by a quick descent in association with the downward motion of the photoionization production peak. This constitutes what is known as the equatorial sunrise undulation. Its anecdotal existence has been reported over Jicamarca while it has been seen repeatedly over Trivandrum, India, during equinox conditions. By contrast, we find that the phenomenon is not as frequent at Jicamarca as at Trivandrum. Using incoherent backscatter radar data from Jicamarca, we show that the differences have an electrodynamical origin. The sunrise undulation gets masked when remnant plasma from the previous night does not move down to low enough altitude. The nighttime residual ion density and its altitude are found to be strongly influenced by the evening and nighttime electric field. There is a strong association between a strong plasma uplift at sunset and the appearance of an undulation at sunrise around the magnetic equator.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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".