Impact of Asian pollution on the UTLS derived from in situ observations of a wide range of trace gases during the HALO PHILEAS mission in autumn 2023
Notice bibliographique
Résumé
Due to fast industrial growth and a high population density East Asia has become one of the most polluted regions on Earth. In combination with the world’s largest convective system, the Asian summer monsoon (ASM), East Asia now is the most significant source region of pollutants entering the upper troposphere and lower stratosphere (UTLS). Thus, understanding their transport pathways and the corresponding time scales of their transport and mixing into the UTLS as well as their impact on the UTLS’s sensitive chemical composition is of crucial importance for precise climate predictions but is not yet fully achieved.To tackle these questions we use in situ measurements of our multi tracer instrument HAGAR-V (High Altitude Gas Analyzer – 5 channel version) during the German research aircraft HALO mission PHILEAS in August/September 2023. Flights from Germany and from Alaska targeted plumes and filaments of ASM air masses in the UTLS above the Mediterranean, the North Pacific, Alaska and Canada. HAGAR-V measured a suite of 30 trace gases including very short-lived NMHCs (e.g. Benzene, C2H2, C4H10), halogenated VOC (e.g. CH2Cl2, CHCl3, C2Cl4, CH2Br2), as well as longer-lived halocarbons (e.g. CH3Cl, CH3Br, CCl4, Halons, HCFCs, and HFCs) every 120 s using in-flight gas chromatography and mass spectrometry. Further long-lived species, including the age-of-air tracer SF6, were measured every 40 s (F12, SF6) and every 80 s (F11, F113, H1211) using electron capture detection.Tracer-tracer relations of species with different source regions and/or atmospheric lifetimes provide insight on sampled air mass origin, mixing, and transport times from the source region to the location of measurement. As shown by Lauther et al. (ACP, 2022) CH2Cl2 is an ideal anthropogenic tracer to identify air masses originating from the ASM region. In the UTLS we find increases of CH2Cl2 by up to 500 % compared to tropospheric background correlating well with other species like SF6, HCFC22, CHCl3, C2Cl4, C2H2, Benzene, and C2H5Cl. The latter three species have tropospheric lifetimes of days to weeks implying that such correlations suggest fast transport from the ASM region to the UTLS. Furthermore, up to 1 ppt enhancement of SF6 in air masses originating from the ASM region suggest a significant ASM-induced negative bias in mean age of air derived from SF6.Tracer-tracer relations of ASM-enhanced short-lived tracers (e.g. CH2Cl2, CHCl3) with long-lived tracers (e.g. F12, N2O) indicate isentropic mixing of polluted air masses into the stratospheric background. In addition, species with more diverse source regions like CH3Br (rural anthropogenic, biomass burning and oceanic), CHCl3 (industrial, soil, and oceanic), CH2Br2 (mainly oceanic), or C2H2 (anthropogenic combustion and biomass burning) yield several different correlation slopes against CH2Cl2. These relations provide an empirical tool that, along with simulated surface origin tracers of the CLaMS (Chemical Lagrangian Model of the Stratosphere) model, further helps to distinguish the origin of the sampled air masses.
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 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 ».