Description du projet
Évaluer le ralentissement prévu de la circulation océanique méridienne de retournement
Comment l’eau douce atteint-elle les régions de convection profonde? Le projet TERIFIC financé par l’UE permettra de faire la lumière sur les chemins empruntés par l’eau douce et les processus de restratification à petite échelle. Les études d’observation classiques ne peuvent pas saisir la variabilité spatiale et temporale de ces processus sans impliquer des coûts démesurés. En exploitant les progrès récents en électronique à petite échelle, TERIFIC engagera un grand nombre de mini dériveurs sur les berges du Groenland et emploiera des plateformes autonomes sous-marines et en surface pour caractériser l’équilibre des processus qui contrôlent la convection et la restratification. Les résultats de ce projet faciliteront le travail des chercheurs pour évaluer comment un ralentissement de la circulation océanique méridienne de retournement (MOC) aura lieu. La MOC est responsable du transport de chaleur vers le pôle ainsi que du stockage de la chaleur profonde et du carbone.
Objectif
The ocean Meridional Overturning Circulation (MOC) is responsible for poleward heat transport, and deep storage of heat and carbon. Climate models generally predict that a slowdown of the MOC will occur this century, with dramatic regional and global climate changes, but how the slowdown will occur is subject to debate. It is widely recognised that convection -- the downward limb of the MOC -- is sensitive to freshwater fluxes, and recent investigations have suggested that the increased melt from the Greenland Ice Sheet has already reduced convection. Yet in 2015, convection returned, and was anomalously strong. Despite the expectation that the MOC is sensitive to freshwater forcing, we do not understand the processes by which freshwater inputs influence the MOC.
The two key gaps in our understanding are: how freshwater reaches the regions of deep convection, and the relative importance of freshwater to convection and restratification. Numerical simulations give conflicting results on freshwater pathways, and convective parameterisations neglect small-scale restratifying processes. Traditional observational approaches cannot capture the spatial and temporal variability of these processes without inordinate cost.
TERIFIC addresses these gaps in understanding through new observations, leveraging recent advances in small-scale electronics to deploy large numbers of mini-drifters on the shelves of Greenland, and employing subsurface and surface autonomous platforms to characterise the balance of processes controlling convection and restratification. The analysis of these observations will answer fundamental questions about how freshwater reaches and affects the regions of deep convection, and enable a critical ground truth of numerical simulations of these processes for climate models.
Champ scientifique
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Régime de financement
ERC-STG - Starting GrantInstitution d’accueil
20148 Hamburg
Allemagne