On the bow shock θ<sub><i>Bn</i></sub> dependence of upstream 70 keV to 2 MeV ion fluxes
Bibliographic record
Abstract
We present a statistical study of 216 energetic ion events observed just upstream of Earth's bow shock by the Wind spacecraft. The ions that compose this database range in energy from 27 keV to 2 MeV. Of particular interest is the effect of shock geometry on the properties of the energetic ions. Our approach is different from previous studies in that we only include upstream ion events associated with a local bow shock crossing. In this way we determine the shock geometry locally, rather than from extrapolations of remote upstream observations to a model shock source location, providing a better quantitative determination of the properties of the energetic ions in relation to shock geometry. Under typical interplanetary conditions in the absence of a preexisting population of ambient energetic ions (E ≥ 50 keV), we find that the ion energy spectrum is characterized by an energy cutoff at ∼200–330 keV. Neither the energy cutoff nor the energetic ion spectrum show any dependence on shock geometry as measured by the angle between the shock normal and magnetic field θBn. However, when an ambient population of energetic particles is present in the interplanetary medium, ion flux levels measured just upstream of the terrestrial shock reach a minimum near θBn ∼ 45° irrespective of energy. The energy spectrum spans up to ∼2 MeV. Moreover, ions with energies E ≥ 550 keV are observed only at θBn ≥ 45°. The flux levels of these more energetic ions increase, in an average sense, with increasing values of θBn. Lee's [1982] self‐consistent theory of ion diffusive shock acceleration appears to explain the energetic ion flux levels observed at θBn ≤ 40°. Upstream energetic ions with energies E ≥ 550 keV appear to be the result of shock drift acceleration.
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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 | 0.003 |
| 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) | 0.001 | 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".