Mechanisms of near-surface current and upwelling variability in the tropical Atlantic
Notice bibliographique
Résumé
In the eastern equatorial oceans upwelling regions are found. The cold upwelling waters not only interact with the atmospheric circulation via changing the sea surface temperatures (SSTs) but also influence the biological activity via affecting the nutrient and oxygen contents. However, the sources of the upwelling waters are well known only for the sources of the equatorial upwelling but remained unclear for the off-equatorial upwelling regions. A main aspect of this work is to contribute to the understanding of the mean pathways into the Guinea and Angola Dome. The analysis bases on a high resolution model (1/12±) of the Atlantic and will focus on a discussion of the role of the various zonal current bands in supplying the offequatorial upwelling. Longer term variability of the equatorial currents and their possible influence on the equatorial upwelling will be discussed in a second part of this work. In the first part of the work trajectory calculations were used to investigate the sources of the equatorial zonal currents. It could be shown that they belong almost exclusively to the southern hemisphere and additionally, strong interaction between the different zonal currents has been found. This interaction is caused by tropical instability waves which are created by the shear between the zonal currents. The waves produce also eddies which cause a watermass transfer between the different currents. It was shown, that this eddy-transport is the main watermass pathway supplying the southern equatorial undercurrent (SEUC) and it was also found to play a major role for the sources of the northern equatorial undercurrent (NEUC). The analysis of the pathways between NEUC, SEUC and the eastern upwelling regions revealed that the NEUC feds into the Guinea Dome, into the equatorial upwelling (via retroflection into the equatorial undercurrent (EUC)) as well as into the upwelling along the African coast, while most of the SEUC waters recirculate in the equatorial zonal currents. The second part of this work focused on interannual to decadal variability of the equatorial currents related to fluctuations of the subtropical-tropical cell (STC) and the conveyor belt (MOC) return flow. For the discussion of these phenomena different sensitivity experiments have been performed using lower resolution models as a FLAME 1/3± Atlantic model and the 1/2± global ORCA configuration. The results from both models were found to be very similar and showed that the STC is not varying coherently, thus there is no obvious interaction between subtropical and tropical variability. In fact, the STCs are driven mainly by the local zonal wind stress. Despite the overriding importance of the wind-forced variability on interannual timescales, all model results showed also decadal variability signals. They were found to belong to variations of the deep water export across equator which is influenced by the formation rate of Labrador Sea Water. These MOC anomalies revealed a basin-wide structure and were found to modulate the shallow transports in the tropical Atlantic on decadal timescales. However, the main signal of the MOC anomalies was found to be confined to the deep and intermediate waters and the amplitudes in vicinity of the surface are negligible.
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 distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,004 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 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 tête enseignante, 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 ».