  The influence of the Atlantic Multidecadal Variability (AMV) and its
amplitude on the Euro-Mediterranean summer climate is studied in two climate
models, namely CNRM-CM5 and EC-Earth3P. Large ensembles of idealized
experiments have been conducted in which North Atlantic sea surface
temperatures (SSTs) are relaxed towards different amplitudes of the observed
AMV anomalies. In agreement with observations, during a positive phase of the
AMV both models simulate an increase (decrease) of temperature and a decrease
(increase) of precipitation over the Mediterranean basin (northern half of
Europe). An increase in the number of heat wave (HW) days is also found over
the continental Mediterranean region. In terms of atmospheric circulation, an
anomalous ridge (trough) over the Mediterranean basin (northern Europe) induces
a thermodynamical response explaining the increase in the occurrence of HW. The
anticyclonic anomaly over the Mediterranean basin is associated with drier
soils and a reduction of cloud cover, which concomitantly induce a decrease
(increase) of the latent (sensible) heat flux and an increase of the downward
radiative fluxes over lands. The source mechanisms leading to the
mid-troposphere anomalies over North Atlantic and its adjacent continents are
discussed. It is found that both the tropical and extra-tropical parts of the
AMV modulate the atmospheric circulation over the Euro-Atlantic region. The
number of HW days increases linearly with the amplitude of the AMV. However,
the strength of this relationship differs between the models, and depends on
their intrinsic biases, raising questions regarding the robustness of the
mechanisms of teleconnections associated with the AMV.
