Dynamic Coupling And Chemical Transport Between The Stratosphere And The Troposphere
Notice bibliographique
Résumé
Although the stratosphere and troposphere are separately different in many aspects (thermal structure, dynamic circulation, chemical composition and etc.), studies in recent decades have indicated a much stronger connection between these two distinct layers. Dynamically, the stratospheric circulation is driven by the eddies that are dominantly generated in the troposphere, whereas the troospheric circulation varies, in some ocassion, mostly due to the circulation and eddy perturbation originated in the stratosphere. The exchange and transport between the two layers, on the other hand, tend to alter the chemical compostion on both sides, and hence induce subsequent influences on the chemistry and radiation within the two layers. In this study, we further enrich the understanding on the connection between the stratosphere and troposphere by examining their dynamic coupling and chemical exchange. We first investigate the dynamic impact from the troposphere to the stratosphere by examining the role of tropical sea surface temperature (SST). By designing several idealized SST forcing simulations in an aqua-planet model, we find that the zonal distribution of SST perturbations has a major impact on the vertical and meridional structure of the BDC as compared with other SST characteristics. Zonally localized SST heatings tend to generate a shallow acceleration of the stratospheric residual circulation, whereas SST heatings with a zonally symmetric structure tend to produce a deep strengthening of the stratospheric residual circulation. The shallow versus deep strengthening of the stratospheric residual circulation change has been linked to wave propagation and dissipation in the subtropical lower stratosphere rather than wave generation in the troposphere. The dynamic impact from the stratosphere to the troposphere is then discussed by focusing on the downward influence of polar stratospheric ozone depletion. Three possible mechanisms are examined in an idealized dry model: the polar stratospheric cooling impacts tropospheric synoptic eddies via (a) the direct influences on the lower stratospheric synoptic eddies, (b) the planetary wave-induced residual circulation, and (c) the planetary eddy - synoptic eddy nonlinear interaction. It is argued that the planetary wave-induced residual circulation is not the dominant mechanism, and that the planetary eddies and further nonlinear interaction with synoptic eddies are more likely the key to the downward influence of the ozone depletion-like cooling. Last, the chemical interaction between the stratosphere and troposphere is explored by quantifying the stratosphere-troposphere exchange (STE) of ozone. The specified dynamics (SD) version of the Whole Atmosphere Community Climate Model (WACCM) is used to estimate the ozone STE along different isentropic surfaces (isentropic ozone STE herein). Net troposphere-to-stratosphere ozone STE is diagnosed in the subtropics (350 K - 380 K), while net stratosphereto-troposphere ozone STE is diagnosed in the extratropics (280 K - 350 K), with different magnitudes and seasonalities over different isentropic (meridional) regions. Potential vorticity (PV) sources induced by both differential diabatic heating and isentropic mixing contribute to the diagnosed isentropic ozone STE flux, but the latter is slightly larger. Moreover, results in the SD-WACCM are generally consistent with the analysis in a different model, the SD version of the Canadian Middle Atmosphere Model (CMAM), but the SD-CMAM diagnoses a smaller STE flux. This difference is associated with the different extent of isentropic mixing between the two models.
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 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 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 ».