Where does the freshwater go?: Pathways for Greenland and Arctic waters from the east Greenland shelf to the North Atlantic
Notice bibliographique
Résumé
In the Atlantic, the ocean circulation transports warm and light waters northwards at the surface, and cold and dense waters southwards at depth. This large-scale circulation is called Atlantic Meridional Overturning Circulation (AMOC) and is a key element of the climate system. Increasing fluxes of freshwater from Greenland and the Arctic to the Subpolar North Atlantic (SPNA) could contribute to the weakening of the AMOC in a changing climate by inhibiting deep convection and the formation of deep waters in the Labrador Sea, Irminger Sea and Nordic Seas. However, these fresh waters are first advected over the Greenland continental shelf by narrow western boundary currents. While west of Greenland, both eddies and winds are known to play a role in steering shelf waters into the interior of the Labrador Sea, possible pathways for freshwater into the Irminger and Nordic Seas east of Greenland have been less studied. As recent observations demonstrated the importance of overturning east of Greenland for the AMOC, it is critical to better understand how fresh shelf waters reach these regions. To do so, I used a new observational dataset, composed of 120 surface drifters deployed in five different regions of the east Greenland shelf between 2019 and 2022. Trajectories from these surface drifters show very limited advection of fresh shelf waters into the Irminger Sea and the Nordic Seas. Some areas of the east Greenland shelf are more favourable to export, and eddies and winds can drive local exchanges between the shelf and neighbouring seas. For instance, I show that at the southern tip of Greenland, strong westerly wind events can drive fresh surface waters off-shelf. This new drifter dataset also allowed to investigate the surface circulation over the shelf in areas where observations were so far sparse. The western boundary current that flows along the east Greenland coast is composed of two distinct branches, and I show that the complex shape of the seabed causes these branches to interact. This leads to further constrain of fresh waters towards the coast along the south-east Greenland shelf, and to a spreading of fresh coastal waters towards the edge of the continental shelf at the southern tip of Greenland. The small scale of the east Greenland shelf is a major challenge for the ability of climate models to correctly represent the circulation of fresh shelf waters and where they exit the shelf. Using the HadGEM3 climate models at different resolution, I show that while the one-degree resolution model is unable to represent the circulation around Greenland, increasing the resolution to 0.25 and 0.12 degrees is not sufficient to properly represent cross-shelf exchanges, even though it allows for a better representation of the circulation. This misrepresentation can lead to under or overestimation of freshwater export into the interior seas of the SPNA. Further observational and modelling studies are necessary to understand exchanges between the north-east Greenland shelf and the Nordic Seas, the role of sea ice, and to quantify the input of freshwater to deep convection regions.
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 | 0,000 | 0,000 |
| 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 | 0,001 | 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 ».