Long‐term variation of the polar wind velocity and its implication for the ion acceleration process: Akebono/suprathermal ion mass spectrometer observations
Bibliographic record
Abstract
We present the solar activity dependence and seasonal variation of H+ and O+ polar wind velocity profiles observed by the suprathermal ion mass spectrometer (SMS) on Akebono. These observations spanned a solar cycle and covered a wide range of altitudes and invariant latitudes (ILAT) in the polar ionosphere and a variety of geomagnetic activity conditions from 1500 km to 8500 km altitude and from the poleward edge of the ionospheric trough (∼60° ILAT) to the polar cap (>85° ILAT). At low (high) altitudes below (above) 4000 km, the increase of the averaged H+ and O+ ion velocities with altitude was larger (smaller) at solar minimum than at solar maximum. For example, the averaged H+ velocity on the dayside at 4000 km altitude was approximately 8 km s −1 at low solar activity but ∼5 km s −1 at high activity. This suggests that the averaged polar wind velocity correlates differently with solar activity and the dominant acceleration process may be different at low and high altitudes, respectively. For both H+ and O+ the observed ion velocity at high altitude was largest in the summer under essentially all magnetic and solar activity conditions. The O+ velocity at high altitude (>4000 km) was significant and largest in the summer at solar maximum, when the solar energy input into the polar cap was largest; theoretically, the velocity of O+ ions in the polar wind is expected to be negligible below 10,000 km. We consider geophysical processes that may contribute to the observed velocities and their solar activity and seasonal dependences, including the possible contributions of photoelectrons and elevated electron temperatures to the ambipolar electric field that drives the polar wind.
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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 | 0.000 |
| 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 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".