  The teleconnection between European climate and Atlantic Multidecadal
Variability (AMV) remains difficult to isolate in observations because of
internal variability and anthropogenically-forced signals. Using model
sensitivity experiments proposed within the CMIP6/DCPP-C framework, the
wintertime AMV/Europe teleconnection is investigated in large ensembles of
pacemaker-type simulations in the CNRM-CM5 global circulation model. To
evaluate the sensitivity of the model response to the AMV amplitude,
experiments with AMV-forcing pattern multiplied by 2 and 3 (hereafter 2xAMV and
3xAMV, respectively) are performed in complement to the reference ensemble
(1xAMV). Based on a flow analog method, the AMV-forced atmospheric circulation
is found to cool down the European continent, whereas the residual signal,
mostly including thermodynamical processes, contributes to warming. In 1xAMV,
both terms cancel each other, explaining the overall weak AMV-forced
atmospheric signal. In 2xAMV and 3xAMV, the thermodynamical contribution
overcomes the dynamical cooling and is responsible for milder and wetter
conditions. The thermodynamical term includes the advection of warmer and more
humid oceanic air penetrating inland and the modification of surface radiative
fluxes linked to (i) altered cloudiness and (ii) snow-cover reduction acting as
a positive feedback with the AMV amplitude. The dynamical anomalous circulation
combines (i) a remote response to enhanced diabatic heating acting as a
Rossby-wave source in the western tropical Atlantic and (ii) a local response
associated with warmer SST over the subpolar gyre favorizing an anomalous High.
The weight between the tropical-extratropical processes and associated
feedbacks is speculated to partly explain the nonlinear sensibility of the
response to the AMV-forcing amplitude, challenging thus the use of the
so-called pattern-scaling technique.
