Black carbon (BC) aerosols are major climate forcers due to their strong light absorption. Current models often estimate this effect by assuming single-core BC particles. Observations of wildfire smoke indicate that ~21% of BC-containing particles exhibit multiple cores, particularly those with diameters > 400 nm and core diameters > 200 nm. These multi-core BC particles were found to enhance light absorption by 82% compared to traditional single-core assumptions, based on dynamic effective medium approximation (DEMA) modelling. Inspired by these observations, we developed a machine-learning emulator for DEMA-based absorption enhancements and incorporated it into a global atmospheric model. Our results show that the enhanced absorption of multi-core BC led to a 19% increase in the global BC absorption aerosol optical depth. This study underscores the critical role of multi-core BC in amplifying radiative forcing, highlighting the necessity for revised models to better capture BC’s impact on the global climate.
 

Black Carbon,Absorption Enhancement