Abstract
AbstractThe AMOC (Atlantic Meridional Overturning Circulation) is a key driver of climate variability. Our understanding, based largely on climate models, is that the Labrador Sea has an important role in shaping the evolution of the AMOC. However, a recent high‐profile observational campaign (Overturning in the Subpolar North Atlantic, OSNAP) has called into question the importance of the Labrador Sea, and hence the credibility of the AMOC representation in climate models. Here, we attempt to reconcile these viewpoints by making the first direct comparison between OSNAP and a coupled climate model. The model compares well to the observations, demonstrating a more prominent role for overturning in the eastern than western subpolar gyre. Density anomalies generated by surface forcing in the Irminger Sea propagate into the Labrador Sea, where they dominate the density variability. Thus, the Labrador Sea may not be the origin of AMOC variability despite correlations with densities there.
Highlights
The Atlantic Meridional Overturning Circulation (AMOC) is a key player in global climate through its meridional heat transport and ability to sequester anthropogenic carbon in the deep ocean (Buckley & Marshall, 2016)
Time Mean In order to begin the reconciliation of the climate model paradigm and new Overturning in the Subpolar North Atlantic Program (OSNAP) observations, we compare our model to these observations
We have shown that the model well represents both the time mean and monthly variability across both OSNAP sections and that it captures the relative dominance of OSNAP-E over OSNAP-W
Summary
The Atlantic Meridional Overturning Circulation (AMOC) is a key player in global climate through its meridional heat transport and ability to sequester anthropogenic carbon in the deep ocean (Buckley & Marshall, 2016). According to paleorecords and experiments with a wide variety of simple to complex climate models, it may be sensitive to changes in the climate, such as global warming and ice melt (freshening) from Greenland and the Arctic (Gregory et al, 2005; Stommel, 1961; Stouffer et al, 2006; Thornalley et al, 2018; Wood et al, 1999) It may be predictable on decadal timescales (Robson et al, 2018), which would be valuable given the potential relationship between the AMOC and North Atlantic sea surface temperatures (Rahmstorf et al, 2015; Zhang & Wang, 2013) as well as the climate impacts of a shutdown of this circulation (Jackson et al, 2015).
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