Impact of aerosol on sea surface temperature over the subtropical Atlantic Ocean: A potential trigger factor of the NAO phase conversion?

The North Atlantic Oscillation (NAO) is one of the most prominent patterns of atmospheric circulation variability over the Northern hemisphere, yet little is known about its underlying mechanism of phase conversion. Our analysis reveals that the recent decline of Aerosol Optical Depth (AOD) over the Subtropical Atlantic Ocean (SAO) contributes significantly to the enhancement of SAO Sea Surface Temperature (SST). We further show that the aerosol variations over SAO appear to be a trigger factor of NAO phase conversion. A new conceptual model, which details for the first time the atmospheric thermodynamic and dynamic anomaly structures during positive and negative NAO phase, has been presented here to illustrate the impact of aerosol on the SST over the SAO and the atmospheric response of the NAO.