Abstract
Using the depth (z) and density (ϱ) frameworks, we analyze local
contributions to AMOC variability in a 900-year simulation with the AWI
climate model. Both frameworks reveal a consistent interdecadal
variability, however the correlation between their maxima deteriorates
on year-to-year scales. We demonstrate the utility of analyzing the
spatial patterns of sinking and diapycnal transformations through depth
levels and isopycnals. The success of this analysis relies on the
spatial binning of these maps which is especially crucial for the maps
of vertical velocities which appear to be too noisy in the main regions
of up- and downwelling because of stepwise bottom topography.
Furthermore, we show that the AMOC responds to fast (annual or faster)
fluctuations in atmospheric forcing associated with the NAO. This
response is more obvious in the ϱ than in the z framework. In
contrast, the link between AMOC deep water production south of Greenland
is found for slower fluctuations and is consistent between the
frameworks.