1456 / 2024-09-27 14:17:40

The role of rising Asian aerosol emissions in shaping the North Atlantic warming hole

Subpolar North Atlantic,AMOC,warming hole,Aerosol

Session 41 - The Atlantic Meridional Overturning Circulation Variability and its Climatic Impacts

Over the past century, the sea surface temperature (SST) in the subpolar North Atlantic (SPNA) has decreased, resulting in the North Atlantic warming hole. While anthropogenic aerosols (AAs) have been linked to this phenomenon, the specific role of remote Asian AAs remains unclear. Using an ensemble of fully coupled experiments with idealized radiative forcing, we reveal a two-stage response of the upper ocean temperature in the SPNA to increased Asian AAs. The initial, fast response is characterized by anomalous warming in the northern SPNA, delaying the formation of the warming hole. This warming arises from the suppression of turbulent heat flux losses driven by anomalous easterly winds, with downwelling Rossby waves further redistributing heat along waveguides. On longer timescales, the initial warming transitions into widespread cooling across the SPNA, resembling the observed warming hole. This cooling is primarily driven by a reduction in northward heat transport due to a weakening of Atlantic Meridional Overturning Circulation, as well as the anomalous southward transport of Labrador cold water. Our findings underscore the significant influence of regional AA emissions on air-sea interaction in the North Atlantic and the development of the warming hole.