Core ion interactions with BB ELF, lower hybrid, and Alfvén waves in the high‐latitude topside ionosphere
Bibliographic record
Abstract
We present simultaneous observations of ion distribution functions and plasma waves in the high‐latitude topside ionosphere (500–1000 km) near local midnight during substorm activation. Using a new instrument, the Suprathermal Ion Imager (SII), we are able to explore two‐dimensional ion distribution functions with unprecedented resolution in time (93 s −1 ) and energy, focusing on the lowest‐energy core (<1 eV) population and suprathermal extensions thereof. The GEODESIC sounding rocket flew through regions containing broadband extremely low frequency (BB ELF) waves, large‐amplitude Alfvén waves, and lower‐hybrid solitary structures (LHSS), all of which have been shown previously to correlate with ion heating. However, GEODESIC detected heating only in association with LHSS. Ion distributions in and near LHSS showed acceleration in the direction transverse to (TAI) with temperatures as high as 5–10 eV, appearing in regions 65 ± 25 m across. TAI were centered on much smaller structures (∼20 m across) of depleted plasma density and enhanced perpendicular electric fields from 0.1 to 10 kHz, consistent with observations from previous rocket flights. Also in agreement with previous findings, we find two distinct ion populations inside LHSS. The dominant population is composed of unheated, isotropic “core” Maxwellian ions having temperatures comparable to the surrounding ambient plasma, while roughly 10% of the plasma density corresponds to the TAI at pitch angles of 90 ± 5°. We argue that the TAI associated with LHSS is consistent with bulk heating of the core ions, and we describe two scenarios that can lead to the observed two‐temperature distributions. The BB ELF wave emissions were correlated with LHSS heating at short scales and anticorrelated with auroral electron precipitation at large scales. The GEODESIC instruments observed no large‐scale ion heating in association with BB ELF waves. Similarly, no ion heating was detected in the presence of large‐amplitude, short perpendicular wavelength Alfvén waves.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".