Winter interactions between aerosols and weather regimes in the North-Atlantic European region

International audienceThis study aims at understanding the winter interactions between aerosols and weather regimes in the North-Atlantic European (NAE) region. As a first step, a six year simulation of sulphate, black carbon (BC) and dust is performed with a Chemical Transport Model (CTM), forced by the meteorological data issued from the European Centre for Medium-range Weather Forecast Integrated Forecast System (ECMWF IFS) model. The CTM uses the emissions inventory of aerosols and precursors gases provided by the “AERosol Comparison between Observations and Models” (AEROCOM) project. In this experiment, atmospheric dynamical processes associated with the different regimes can impact by up to 25% the burden of sulphate and BC and by up to 80% the burden of mineral dust, through the modification of deposition, transport and chemistry processes. As a second step, the patterns of aerosol anomalies induced by each weather regime are used to force experiments performed with an Atmosphere General Circulation Model (AGCM). The mean persistence of the negative phase of the North Atlantic Oscillation (NAO-) and the Zonal regime are reduced by 1.78 and 0.88 days respectively when the atmosphere is forced with the patterns of aerosols induced by the Zonal regime and the Blocking regime respectively. This suggests that the interaction between the atmosphere and its aerosol concentration could destabilize the NAO- regime which occurs after a Zonal episode. Same conclusion can be set out for a Zonal regime which occurs after a Blocking episode