Particle size amplification of black carbon by scattering measurement due to morphology diversity

Abstract

Black carbon (BC) is an important aerosol species due to its strong heating of the atmosphere accompanied by cooling of the Earth’s surface, but its radiative forcing is poorly constrained by different regional size distributions due to uncertain reproductions of a morphologically simplified model. Here, we quantify the BC morphological effect on measuring the particle size using an aggregate model. We show that the size distributions of loose BC particles could account for up to 45% underestimation by morphological simplification, leading to up to 25% differences, by relying on a simplified model to estimate radiative forcing. We find that the BC particle size is remarkably amplified for looser and larger BC aggregates by angular scattering observations. We suggest that the BC morphological diversity can be neglected in forward scattering angles (<30°), which is a useful supplement to reduce the uncertainty of radiative forcing assessment.