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Abstract:
In EGU General Assembly 2024, Vienna, Austria & Online
Black carbon (BC) aerosol can strongly influence planetary boundary layer (PBL) development and thus severe hazeformation, but its distinct role compared with scattering aerosols are not yet fully understood. Here, combiningnumerical simulation and field observation, we found a “tipping point”, where the daily maximum PBL heightdecreases abruptly when exceeding a critical threshold of aerosol optical depth (AOD), due to a BC-induced decouplingof mixing zones. Because the threshold AOD decreases with increasing BC mass fraction, our results suggest that theabrupt transition of PBL development to adverse conditions can be avoided by reducing the AOD below the threshold,but more efficiently by reducing the BC mass fraction to increase the threshold (e.g., up to 4-6 times more effective inextreme haze events in Beijing). To achieve co-benefits for air quality and climate change, our findings clearlydemonstrate that high priority should be given to controlling BC emissions.
