Twenty-first century Southern Hemisphere impacts of ozone recovery and climate change from the stratosphere to the ocean
Notice bibliographique
Résumé
Abstract. Changes in stratospheric ozone concentrations and increasing concentrations of greenhouse gases (GHGs) alter the temperature structure of the atmosphere and drive changes in the atmospheric and oceanic circulation. We systematically investigate the impacts of ozone recovery and increasing GHGs on the atmospheric and oceanic circulation in the Southern Hemisphere during the twenty-first century using a unique coupled ocean-atmosphere climate model with interactive ozone chemistry and enhanced oceanic resolution. We use the high emission scenario SSP5-8.5 for GHGs under which the springtime Antarctic total column ozone returns to 1980s levels by 2048 in our model, warming the lower stratosphere and strengthening the stratospheric westerly winds. Novel results of this study include the springtime stratospheric circulation response to GHGs, which is characterized by changes of opposing sign over the Eastern and Western Hemispheres, the opposing responses of the Agulhas leakage to ozone recovery and increasing GHGs, and large uncertainties in the prediction of atmospheric and oceanic circulation changes related to whether the ozone field is prescribed or calculated interactively. By performing a thorough spatial analysis of the predicted changes in the stratospheric dynamics, we find that the GHG effect during spring exhibits a strong dipole pattern, which contrasts the GHG effect during the rest of the year and which was previously not reported, as it cannot be detected when zonal means are considered. Over the Western Hemisphere, GHGs drive a warming of the lower stratosphere and a weakening of the westerlies, while over the Eastern Hemisphere they drive a cooling and a strengthening of the westerlies. Associated with these changes, planetary waves break higher up in the stratosphere over the Eastern Hemisphere, strengthening the polar downwelling and inducing dynamical warming in the upper stratosphere, while weakening the downwelling and inducing dynamical cooling in the lower stratosphere. The opposite occurs over the Western Hemisphere. Because the changes in the Western Hemisphere dominate during November in our model, we find that during this month GHGs lead to a weakening of the lower branch of the Brewer-Dobson Circulation, reinforcing the weakening caused by ozone recovery. At the surface, the westerly winds weaken and shift equatorward due to ozone recovery, driving a weak decrease in the transport of the Antarctic Circumpolar Current and in the Agulhas leakage, which transports warm and saline waters from the Indian into the Atlantic Ocean. The increasing GHGs drive changes in the opposite direction that overwhelm the ozone effect. The total changes at the surface and in the oceanic circulation are nevertheless weaker in the presence of ozone recovery than those induced by GHGs alone, highlighting the importance of the Montreal Protocol in mitigating some of the impacts of climate change. We additionally compare the combined effect of interactively calculated ozone recovery and increasing GHGs with their combined effect in an ensemble in which we prescribe the CMIP6 ozone field. This second ensemble simulates a weaker ozone effect in all the examined fields. The magnitude of the difference between the simulated changes at the surface and in the oceanic circulation in the two ensembles is as large as the ozone effect itself. This shows that the choice between prescribing or calculating the ozone field interactively can affect the prediction of changes not only in the atmospheric, but also in the oceanic circulation.
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) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,001 |
| 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 | 0,001 |
| 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 ».