Publication Date:
2016-03-01
Description:
This study examines the relationship between the Atlantic Multidecadal Variability (AMV) and the wintertime atmospheric circulation of the North Atlantic in simulations of the 5th Coupled Model Intercomparison Project (CMIP5). Comparisons of internal (using pre-industrial control simulations) and externally-forced (using historical and RCP8.5 simulations) simulated AMV with observations suggest that the CMIP5 models lack internally generated AMV, except for two models (GFDL-ESM2G and HadGEM2-ES). A long-term influence of the winter North Atlantic Oscillation (NAO) on the AMV is identified, but no consistent feedback of the AMV onto the atmospheric circulation is found amongst the models. However, GFDL-ESM2G and HadGEM2-ES show a small lagged NAO signal that suggests a driving role of the ocean on decadal fluctuations of the atmosphere, with two different potential mechanisms. HadGEM2-ES exhibits a latitudinal shift of the Atlantic ITCZ that can modulate the NAO through a Rossby wave train emanating from the tropics. In GFDL-ESM2G, the AMV is associated with a decrease in storm track activity and a shift of the intraseasonal weather regimes towards the negative NAO regime. These results raise hope that some long term predictability of the winter climate over the North Atlantic and surrounding continents could be extracted from long term oceanic fluctuations of the North Atlantic ocean, provided that the AMV is correctly represented in coupled ocean-atmosphere models.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
Permalink