Calculation of photoelectron induced UV emission with application to the SMILE mission
Notice bibliographique
Résumé
The SMILE mission, supported by the European Space Agency and the Chinese Academy of Sciences, is scheduled for launch in 2024. The mission is augmented by a substantial ground-based network of optical ASI's. Here, we report progress in developing a numerical model of UV emissions to aid interpretation of images collected by the SMILE UVI. The model calculates UV emissions produced by suprathermal electrons, accounting for prominent UV auroral and dayglow emission lines and bands, including OI 130.4/135.6nm, Lyman-Birge-Hopfield (LBH) and Vegard-Kaplan (VK) bands. It also calculates line-of-sight absorption and the integrated UV photon flux spectrum reaching each UVI-imager pixel. Photoelectron energy spectra for the UV emission module are generated using a Monte Carlo model of photoelectron propagation. This model accounts for 52 kinds of electron-neutral collisions as well as Coulomb collisions. Considering closed geomagnetic field lines in the night sector, and depending on Earth's position relative to the Sun, the model predicts the appearance of energetic photoelectrons coming from the day sector. Coulomb scattering prevents pthese hotoelectrons from reaching the opposite ionosphere [c.f., Khazanov et al, 1994]. To reveal the importance of Coulomb collisions, model photoelectron fluxes and related UV emissions were calculated with Coulomb collisions included and omitted for five locations along the orbit of the DMSP F16 satellite on UT0800 January 1, 2017, which observed anomalous UV emission induced by conjugate photoelectrons [Kil et al., 2020]. Omitting Coulomb collisions overestimates the photoelectron flux and the intensity of UV emission by up to 50% with the effect being more pronounced on longer field lines.Solar EUV photons also produce energetic photoelectrons which ionize neutrals, heat ambient electrons, and cause UV emission. These photoelectrons can penetrate into the nightside even when connected to the day sector by geomagnetic field lines. UV emission caused by such photoelectrons in the night sector is called anomalous UV emission. knowlege of which is important for the analysis of data from the SMILE UVI. The model development for SMILE includes a module that calculates propagation of photoelectrons and related UV emission. Results from the model are benchmarked against observations by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) of the DMSP F16 spacecraft. The spacecraft was in Earths shadow, and traveling towards the equatorial plane. The observed anomalous UV emission rapidly decreases as the spacecraft approaches lower latitudes where field lines are shorter and almost completely in the shadow. Values of the UV emission at wavelengths of 135.6 nm and 130.4 nm were calculated from the model at several locations along the spacecraft orbit. Calculations performed with a tilted dipole geomagnetic field gave values that were significantly larger than the observed ones. Calculations using the International Reference Geomagnetic Field (IGRF) provided much improved agreement between the model and the observation because the IGRF places the southern ends of geomagnetic field lines farther from the sunlit hemisphere. The improved agreement suggests the model development related to the SMILE mission will aid interpretation of the data.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,001 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».