09.05.2022: Ocean Circulation and Climate Dynamics Colloquium

When?     Monday, 09. Mai 2022 at 2 pm
Where?    ZOOM meeting room: https ://geomar-de.zoom.us/j/84342705965?pwd=R0hpSjdQcVN5Rm5CQy9NSGRyQUtqUT09

Meeting-ID: 843 4270 5965
Kenncode: 440768

We would like to inform you that this seminar will be recorded. We will only record the presentation without the Q&A part.

Climate models permit in-depth study of the variability mechanisms and wider impacts of the Atlantic meridional overturning circulation (AMOC), but model fidelity remains a perennial concern. Recent observations from the Overturning in the Subpolar North Atlantic Program (OSNAP) have challenged model-based inferences that the Labrador Sea is a key pacemaker of decadal AMOC and North Atlantic climate variability, instead implicating the eastern subpolar gyre (SPG) as the dominant forcing region for AMOC. In this talk, we present two lines of evidence that suggest that decadal AMOC variability and associated predictability is fundamentally related to Labrador Sea Water (LSW) production in the western subpolar gyre. First, it is shown that intrinsic, decadal AMOC variability in a realistic, eddy-resolving (0.1° ocean) preindustrial control simulation can be traced to anomalous surface formation of LSW in the greater Labrador Sea region, even though the eastern SPG dominates the time-mean surface transformation. Second, the mechanism underpinning high SPG skill in an initialized decadal prediction system using a standard resolution model (1° ocean) involves interior propagation of LSW anomalies from their origination in the Labrador Sea. Taken together, these results highlight the dynamical relevance of the Labrador Sea as the primary source of the densest class of North Atlantic Intermediate Water (NAIW) formed south of the Greenland Scotland Ridge.

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