Velocity of decameter electrojet irregularities under strongly driven conditions
Bibliographic record
Abstract
The Earth ionosphere is a highly inhomogeneous medium containing electron density irregularities of various scales, from hundreds of kilometers to tens of centimeters.Understanding the mechanisms responsible for their formation is an important task for various practical applications such as communication, navigation, and safe satellite operation.Of special interest are the decameter irregularities that are abundant at E-region heights of ~ 100 -120 km.These are excited when enhanced electric field and plasma drifts are setup in the ionosphere.This thesis is aimed at studying the physics of decameter irregularity formation at E-region heights with a focus on the extreme conditions of very strong electric fields (plasma flows) of > 50 mV/m (1000 m/s) for which the so called Farley-Buneman (FB) plasma instability is the dominating mechanism of irregularity excitation.The relationship between the irregularity velocity and plasma drift is investigated by considering data of the SuperDARN radar located at Stokkseyri, Iclenad.The radar detects echoes from the irregularities and is thus capable of measuring their velocity.The DMSP satellites measure the plasma drifts in situ at heights of ~ 800 km, but these measurements can be projected onto E-region heights at high latitudes.By comparing the radar and satellite data in one direction, we show that irregularity velocity is smaller than the plasma drift by a factor of 2 -3 with the stronger difference at faster flows.This contrasts with the theoretical expectation for the velocity to be close to 400 m/s, the nominal ion-acoustic speed at electrojet heights.A twodimensional comparison is performed by considering a subset of the observations for which the HF echo velocity showed a cosine type variation with the radar look direction.This class of echoes is consistent with predictions of recent theories of the Farley-Buneman instability, but the irregularity velocity magnitude was found to be smaller than the ion-acoustic speed with occasional occurrence of velocities as small as 100 m/s.This implies that either recent theories of the Farley-Buneman instability should be modified or that the typical height of HF echoes is typically below 100 km.Various other properties of decameter irregularities are investigated and discussed in view of the existing theories.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.000 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".