Enhanced Coagulation Scavenging of Small Charged Particles and its Impact on Particle Survival Probability in the Atmosphere

Abstract:

New-particle formation is important to aerosol–cloud interaction and thus climate, but for newly formed particles to grow to atmospherically relevant size (e.g. CCN), they must grow and avoid being scavenging by already-existing bigger particles. While ion-induced new-particle formation and ion-enhanced particle growth have received attention recently, here we study an opposing effect: small charged particles are scavenged more efficiently due to their charge, and thus their survival probability (p′) is lower than that of their neutral counterparts (p). Through simulations, we show that this survival probability is reduced, in some cases dramatically, matching theoretical predictions. We also show that charged particle survival is enhanced by neutralization; and so for ion-induced nucleation to be important, charged particles must become neutral as soon as possible.