THEMIS observations of the near‐Earth plasma sheet during a substorm
Bibliographic record
Abstract
We present observations of a substorm on 13 March 2008 by Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft in the near‐Earth tail during the plasma sheet expansion evidenced by increase in the plasma density and temperature. The main features of the event are as follows: (1) Cross‐tail current reduction or current disruption (CD) was observed in the near‐Earth tail at X ∼ −8.0 RE and Y ∼ 2.0 RE, marked by a sharp drop of ∣Bx∣ and accompanied by sharp increases in the plasma density and temperature, manifesting a rapid expansion (recovery) of the local plasma sheet. During the course of the plasma sheet expansion, the propagation speed of the dipolarization is ∼48 km/s in tailward direction and ∼35 km/s in azimuthal direction. (2) In the inner edge of the plasma sheet, slow flux pileup is observed. The magnetic flux pileup is characterized by continuous enhancement of Bz and Bt and a reduction of the plasma density, pressure Pth, and β in the flow‐braking region. The tailward moving plasma sheet expansion (CD) is also passing across the flow‐braking region. In short, the dipolarization in the inner edge of the plasma sheet can be attributed to CD, while the tailward progression of dipolarization in the flow‐braking region can be attributed to magnetic flux pileup. (3) A sharp decrease in the magnitude of Bx at P1 (−13.1 RE, 2.5 RE, −0.56 RE) prior to the dipolarization at P5 is difficult to explain as part of the outward evolution of the CD. The rapid change in the magnetic field topology, and signatures of earthward flows and dipolarization observed at P1 prior to Pi2 onset may be caused by inward motion of flux from magnetic reconnection in the midtail (20–30 RE). Tail reconnection prior to substorm expansion can result in a sudden change of the near‐Earth configuration, which may result in instabilities related to the onset of CD.
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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 | 0.001 | 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) | 0.001 | 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".